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Objective: A 2015 survey of primary care providers (PCPs) found that while many believed that milliliter (mL)-only dosing was safest for oral liquid medications, few would use mL alone in dosing instructions. Since 2015, many recommendations have promoted "mL-only" dosing. In 2019, a follow-up survey was conducted to assess if PCP perceptions and practices have changed., Methods: Pediatricians, family medicine physicians, nurse practitioners, and internists participating in the 2015 and 2019 DocStyles cross-sectional, web-based surveys were asked about their perceptions and practices regarding dosing units for oral liquid medications., Results: In 2019, among 1392 respondents, the proportion of PCPs who reported they believed using mL-only is the safest dosing instruction ranged from 55.1% of internists to 80.8% of pediatricians. While fewer PCPs believed patients/caregivers prefer dosing instructions in mL-only (23.9% of nurse practitioners to 48.4% of pediatricians), more held this belief in 2019 compared to 2015; pediatricians had the greatest absolute increase (+14.4%) and family medicine physicians had the smallest increase (+1.3%). While 61.6% of pediatricians reported they would use mL-only dosing, only 36.0% of internists, 36.6% of nurse practitioners, and 42.5% of family medicine physicians reported they would do so. After controlling for age, gender, region, and specialty, 2019 PCP survey participants were more likely to report that they would use mL-only dosing compared to 2015 participants (adjusted odds ratio 1.51, 95% confidence interval 1.29-1.77)., Conclusions: Broader educational efforts may be necessary to reach nonpediatricians, to encourage prescribing and communication with patients/caregivers using mL-only dosing., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Inc.)

Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Introduction: Emergency department visits and hospitalizations for unsupervised medication exposures among young children increased in the early 2000s. Prevention efforts were initiated in response., Methods: Nationally representative data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project collected from 2009 to 2020 were analyzed in 2022 to assess overall and medication-specific trends in emergency department visits for unsupervised exposures among children aged ≤5 years., Results: From 2009 to 2020, there were an estimated 677,968 (95% CI=550,089, 805,846) emergency department visits for unsupervised medication exposures among children aged ≤5 years in the U.S. Most visits involved children aged 1-2 years (2009-2012 [70.3%], 2017-2020 [67.4%]), and nearly one half involved prescription solid medications (2009-2012 [49.4%], 2017-2020 [48.1%]). The largest declines in estimated numbers of annual visits from 2009-2012 to 2017-2020 were for exposures involving prescription solid benzodiazepines (-2,636 visits, -72.0%) and opioids (-2,596 visits, -53.6%) and over-the-counter liquid cough and cold medications (-1,954 visits, -71.6%) and acetaminophen (-1,418 visits, -53.4%). The estimated number of annual visits increased for exposures involving over-the-counter solid herbal/alternative remedies (+1,028 visits, +65.6%), with the largest increase for melatonin exposures (+1,440 visits, +421.1%). Overall, the estimated number of visits for unsupervised medication exposures decreased from 66,416 in 2009 to 36,564 in 2020 (annual percentage change= -6.0%). Emergent hospitalizations for unsupervised exposures also declined (annual percentage change= -4.5%)., Conclusions: Declines in estimated emergency department visits and hospitalizations for unsupervised medication exposures from 2009 to 2020 coincided with renewed prevention efforts. Targeted approaches may be needed to achieve continued declines in unsupervised medication exposures among young children., (Published by Elsevier Inc.)

Background: Clinical trials suggest lower rates of major bleeding with direct-acting oral anticoagulants (DOACs) than with warfarin, but anticoagulant-related bleeding remains one of the most common outpatient adverse drug events., Methods: We estimated the number of emergency department (ED) visits and subsequent hospitalizations for oral anticoagulant-related bleeding in 2016-2020 based on active surveillance in a nationally representative, size-stratified probability sample of 60 U.S. hospitals. We estimated rates of ED visits using a nationally-projected retail prescription dispensing database., Results: Based on 19,557 cases, oral anticoagulant-related bleeding resulted in an estimated 1,270,259 (95 % Confidence Interval [CI], 644,686-1,895,832) ED visits for the five years 2016-2020, of which 47.8 % (95 % CI, 40.6 %-55.0 %) resulted in hospitalization. Oral anticoagulant-related bleeding resulted in an estimated 230,163 (95% CI, 109,598-350,728) ED visits in 2016 and 301,433 (95% CI, 138,363-464,503) in 2020. During 2016-2020, ED visits for DOAC-related bleeding increased by an average of 27.9 % (95 % CI, 24.0 %-32.0 %; p < .001) per year, while ED visits for warfarin-related bleeding decreased by an average of 8.8 % (95 % CI, -10.7 % to -7.0 %; p = .001) per year. The estimated rate of bleeding visits per 100 patients dispensed oral anticoagulants at least once in 2016-2020 was highest for patients aged ≥ 80 years (13.1; 95 % CI, 6.2-20.0) and lowest for those aged <45 years (4.0; 95 % CI, 2.6-5.5); it was 5.9 visits per 100 patients dispensed DOACs [95 % CI, 2.5-9.2] and 13.0 visits per 100 patients dispensed warfarin [95 % CI, 7.4-18.7]., Conclusions: Although the rates of ED visits for anticoagulant-related bleeding may be lower for DOACs than for warfarin, persistently large numbers of patients requiring ED visits for anticoagulant-related bleeding despite increased use of DOACs and declining use of warfarin suggest that efforts to improve appropriate prescribing and monitoring of anticoagulants remain important., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Background: Medication poisoning is a common form of self-harm injury, and increases in injuries due to self-harm, including suicide attempts, have been reported over the last two decades., Methods: Cross-sectional (2016-2019) data from 60 emergency departments (EDs) participating in an active, nationally representative public health surveillance system were analysed and US national estimates of ED visits for medication-related self-harm injuries were calculated., Results: Based on 18 074 surveillance cases, there were an estimated 269 198 (95% CI 222 059 to 316 337) ED visits for medication-related self-harm injuries annually in 2016-2019 compared with 1 404 090 visits annually from therapeutic use of medications. Population rates of medication-related self-harm ED visits were highest among persons aged 11-19 years (58.5 (95% CI 45.0 to 72.0) per 10 000) and lowest among those aged ≥65 years (6.6 (95% CI 4.4 to 8.8) per 10 000). Among persons aged 11-19 years, the ED visit rate for females was four times that for males (95.4 (95% CI 74.2 to 116.7) vs 23.0 (95% CI 16.4 to 29.6) per 10 000). Medical or psychiatric admission was required for three-quarters (75.1%; 95% CI 70.0% to 80.2%) of visits. Concurrent use of alcohol or illicit substances was documented in 40.2% (95% CI 36.8% to 43.7%) of visits, and multiple medication products were implicated in 38.6% (95% CI 36.8% to 40.4%). The most frequently implicated medication categories varied by patient age., Conclusions: Medication-related self-harm injuries are an important contributor to the overall burden of ED visits and hospitalisations for medication-related harm, with the highest rates among adolescent and young adult females. These findings support continued prevention efforts targeting patients at risk of self-harm., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Purpose: Characterization of emergency department (ED) visits for acute harms related to use of over-the-counter cough and cold medications (CCMs) by patient demographics, intent of CCM use, concurrent substance use, and clinical manifestations can help guide prevention of medication harms., Methods: Public health surveillance data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project were used to estimate numbers and population rates of ED visits from 2017 to 2019., Results: Based on 1396 surveillance cases, there were an estimated 26 735 (95% CI, 21 679-31 791) US ED visits for CCM-related harms annually, accounting for 1.3% (95% CI, 1.2-1.5%) of all ED visits for medication adverse events. Three fifths (61.4%, 95% CI, 55.6-67.2%) of these visits were attributed to non-therapeutic CCM use (nonmedical use, self-harm, unsupervised pediatric exposures). Most visits by children aged <4 years (74.0%, 95% CI, 59.7-88.3%) were for unsupervised CCM exposures. Proportion hospitalized was higher for visits for self-harm (76.5%, 95% CI, 68.9-84.2%) than for visits for nonmedical use (30.3%, 95% CI, 21.1-39.6%) and therapeutic use (8.8%, 95% CI, 5.9-11.8%). Overall, estimated population rates of ED visits for CCM-related harms were higher for patients aged 12-34 years (16.5 per 100 000, 95% CI, 13.0-20.0) compared with patients aged <12 years (5.1 per 100 000, 95% CI, 3.6-6.5) and ≥ 35 years (4.3 per 100 000, 95% CI, 3.4-5.1). Concurrent use of other medications, illicit drugs, or alcohol was frequent in ED visits for nonmedical use (61.3%) and self-harm (75.9%)., Conclusions: Continued national surveillance of CCM-related harms can assess progress toward safer use., (Published 2021. This article is a U.S. Government work and is in the public domain in the USA.)

Importance: Assessing the scope of acute medication harms to patients should include both therapeutic and nontherapeutic medication use., Objective: To describe the characteristics of emergency department (ED) visits for acute harms from both therapeutic and nontherapeutic medication use in the US., Design, Setting, and Participants: Active, nationally representative, public health surveillance based on patient visits to 60 EDs in the US participating in the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance Project from 2017 through 2019., Exposures: Medications implicated in ED visits, with visits attributed to medication harms (adverse events) based on the clinicians' diagnoses and supporting data documented in the medical record., Main Outcomes and Measures: Nationally weighted estimates of ED visits and subsequent hospitalizations for medication harms., Results: Based on 96 925 cases (mean patient age, 49 years; 55% female), there were an estimated 6.1 (95% CI, 4.8-7.5) ED visits for medication harms per 1000 population annually and 38.6% (95% CI, 35.2%-41.9%) resulted in hospitalization. Population rates of ED visits for medication harms were higher for patients aged 65 years or older than for those younger than 65 years (12.1 vs 5.0 [95% CI, 7.4-16.8 vs 4.1-5.8] per 1000 population). Overall, an estimated 69.1% (95% CI, 63.6%-74.7%) of ED visits for medication harms involved therapeutic medication use, but among patients younger than 45 years, an estimated 52.5% (95% CI, 48.1%-56.8%) of visits for medication harms involved nontherapeutic use. The proportions of ED visits for medication harms involving therapeutic use were lowest for barbiturates (6.3%), benzodiazepines (11.1%), nonopioid analgesics (15.7%), and antihistamines (21.8%). By age group, the most frequent medication types and intents of use associated with ED visits for medication harms were therapeutic use of anticoagulants (4.5 [95% CI, 2.3-6.7] per 1000 population) and diabetes agents (1.8 [95% CI, 1.3-2.3] per 1000 population) for patients aged 65 years and older; therapeutic use of diabetes agents (0.8 [95% CI, 0.5-1.0] per 1000 population) for patients aged 45 to 64 years; nontherapeutic use of benzodiazepines (1.0 [95% CI, 0.7-1.3] per 1000 population) for patients aged 25 to 44 years; and unsupervised medication exposures (2.2 [95% CI, 1.8-2.7] per 1000 population) and therapeutic use of antibiotics (1.4 [95% CI, 1.0-1.8] per 1000 population) for children younger than 5 years., Conclusions and Relevance: According to data from 60 nationally representative US emergency departments, visits attributed to medication harms in 2017-2019 were frequent, with variation in products and intent of use by age.

Background: The objective of our study was to describe trends in US outpatient antibiotic prescriptions from January through May 2020 and compare with trends in previous years (2017-2019)., Methods: We used data from the IQVIA Total Patient Tracker to estimate the monthly number of patients dispensed antibiotic prescriptions from retail pharmacies from January 2017 through May 2020. We averaged estimates from 2017 through 2019 and defined expected seasonal change as the average percent change from January to May 2017-2019. We calculated percentage point and volume changes in the number of patients dispensed antibiotics from January to May 2020 exceeding expected seasonal changes. We also calculated average percent change in number of patients dispensed antibiotics per month in 2017-2019 versus 2020. Data were analyzed overall and by agent, class, patient age, state, and prescriber specialty., Results: From January to May 2020, the number of patients dispensed antibiotic prescriptions decreased from 20.3 to 9.9 million, exceeding seasonally expected decreases by 33 percentage points and 6.6 million patients. The largest changes in 2017-2019 versus 2020 were observed in April (-39%) and May (-42%). The number of patients dispensed azithromycin increased from February to March 2020 then decreased. Overall, beyond-expected decreases were greatest among children (≤19 years) and agents used for respiratory infections, dentistry, and surgical prophylaxis., Conclusions: From January 2020 to May 2020, the number of outpatients with antibiotic prescriptions decreased substantially more than would be expected because of seasonal trends alone, possibly related to the coronavirus disease 2019 pandemic and associated mitigation measures., (Published by Oxford University Press for the Infectious Diseases Society of America 2020.)

Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Introduction: Characterization of emergency department visits attributed to adverse events involving benzodiazepines can be used to guide preventive interventions. This study describes U.S. emergency department visits attributed to adverse events involving benzodiazepines by intent, patient characteristics, and clinical manifestations., Methods: Data from the 2016-2017 National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project were analyzed in 2019 to calculate estimated annual numbers and rates of emergency department visits attributed to adverse events involving benzodiazepines, by intent of benzodiazepine use., Results: Based on 6,148 cases, there were an estimated 212,770 (95% CI=167,163, 258,377) emergency department visits annually attributed to adverse events involving benzodiazepines. More than half were visits involving nonmedical use of benzodiazepines (119,008; 55.9%, 95% CI=50.0%, 61.9%), one third were visits involving self-harm with benzodiazepines (64,721; 30.4%, 95% CI=25.6%, 35.2%), and a smaller proportion of visits involved therapeutic use of benzodiazepines (29,041; 13.6%, 95% CI=11.4%, 15.9%). The estimated population rate of visits was highest for nonmedical use of benzodiazepines by patients aged 15-34 years (7.4 visits per 10,000 people). Among visits involving nonmedical use of benzodiazepines, 54.8% (95% CI=49.8%, 59.8%) were made by patients aged 15-34 years, 82.7% (95% CI=80.1%, 85.4%) involved concurrent use of other substances (illicit drugs, alcohol, prescription opioids, and/or other pharmaceuticals), and 24.2% (95% CI=17.7%, 30.6%) involved cardiorespiratory arrest or unresponsiveness., Conclusions: These findings support recommendations to assess for and address substance use disorder before initiating or continuing benzodiazepines and reinforce the need for validated self-harm risk assessment tools for clinicians., (Published by Elsevier Inc.)

Objective: To identify types of containers from which young children accessed solid dose medications (SDMs) during unsupervised medication exposures and the intended recipients of the medications to advance prevention., Study Design: From February to September 2017, 5 US poison centers enrolled individuals calling about unsupervised solid dose medication exposures by children ≤5 years. Study participants answered contextually directed questions about exposure circumstances., Results: Sixty-two percent of eligible callers participated. Among 4496 participants, 71.6% of SDM exposures involved children aged ≤2 years; 33.8% involved only prescription medications, 32.8% involved only over-the-counter (OTC) products that require child-resistant packaging, and 29.9% involved ≥1 OTC product that does not require child-resistant packaging. More than one-half of exposures (51.5%) involving prescription medications involved children accessing medications that had previously been removed from original packaging, compared with 20.8% of exposures involving OTC products (aOR, 3.39; 95% CI, 2.87-4.00). Attention deficit hyperactivity disorder medications (49.3%) and opioids (42.6%) were often not in any container when accessed; anticonvulsants (41.1%), hypoglycemic agents (33.8%), and cardiovascular/antithrombotic agents (30.8%) were often transferred to alternate containers. Grandparents' medications were involved in 30.7% of prescription medication exposures, but only 7.8% of OTC product exposures (aOR, 3.99; 95% CI, 3.26-4.87)., Conclusions: Efforts to reduce pediatric SDM exposures should also address exposures in which adults, rather than children, remove medications from child-resistant packaging. Packaging/storage innovations designed to encourage adults to keep products within child-resistant packaging and specific educational messages could be targeted based on common exposure circumstances, medication classes, and medication intended recipients., (Published by Elsevier Inc.)

Purpose: To identify possible changes in U.S. emergency department (ED) visits from zolpidem-attributed adverse drug reactions (ADRs) after 2013 Food and Drug Administration (FDA) Drug Safety Communications (DSCs), which notified the public about FDA's new dosing recommendations for zolpidem., Methods: We estimated the occurrence of ED visits from zolpidem-attributed ADRs using nationally representative, public health surveillance of medication harms (National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project, 2010-2017). We estimated the number of zolpidem prescriptions using IQVIA National Prescription Audit, 2010-2017. We calculated rates of ED visits for zolpidem-attributed ADRs per 10 000 dispensed zolpidem prescriptions and identified time trends and potential inflection points using joinpoint regression. For comparison, we repeated these analyses for sedating antidepressants commonly used to treat disordered sleep (trazodone, doxepin, and mirtazapine)., Results: The best-fit regression model for rates of ED visits for zolpidem-attributed ADRs by 6-month intervals identified a single inflection point in the second half of 2014 ( P = .024) with a 6.7% biannual decrease from 2010 to 2014 ([-13.1%, 0.3%], P = .059) and a 13.9% biannual increase from the second half of 2014 through 2017 ([-1.1%, 31.3%], P = .068). No change or inflection points were identified for rates of ED visits for sedating antidepressant-attributed ADRs., Conclusions: While there was a nominal decline in the rate of ED visits for ADRs in the time period before and for 18 months after FDA's 2013 zolpidem DSCs, the decrease was not sustained, and thus questions remain concerning the long-term impact of the zolpidem DSCs on ADRs., Competing Interests: CONFLICT OF INTEREST The authors have no conflicts of interest to declare. Funded solely by the U.S. Department of Health and Human Services, which had no role in study design; collection, analysis, and interpretation of data; writing the report; and decision to submit the report for publication.

Background: Antibiotics are among the most commonly prescribed medications for children; however, at least one-third of pediatric antibiotic prescriptions are unnecessary. National data on short-term antibiotic-related harms could inform efforts to reduce overprescribing and to supplement interventions that focus on the long-term benefits of reducing antibiotic resistance., Methods: Frequencies and rates of emergency department (ED) visits for antibiotic adverse drug events (ADEs) in children were estimated using adverse event data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project and retail pharmacy dispensing data from QuintilesIMS (2011-2015)., Results: On the basis of 6542 surveillance cases, an estimated 69464 ED visits (95% confidence interval, 53488-85441) were made annually for antibiotic ADEs among children aged ≤19 years from 2011 to 2015, which accounts for 46.2% of ED visits for ADEs that results from systemic medication. Two-fifths (40.7%) of ED visits for antibiotic ADEs involved a child aged ≤2 years, and 86.1% involved an allergic reaction. Amoxicillin was the most commonly implicated antibiotic among children aged ≤9 years. When we accounted for dispensed prescriptions, the rates of ED visits for antibiotic ADEs declined with increasing age for all antibiotics except sulfamethoxazole-trimethoprim. Amoxicillin had the highest rate of ED visits for antibiotic ADEs among children aged ≤2 years, whereas sulfamethoxazole-trimethoprim resulted in the highest rate among children aged 10 to 19 years (29.9 and 24.2 ED visits per 10000 dispensed prescriptions, respectively)., Conclusions: Antibiotic ADEs lead to many ED visits, particularly among young children. Communicating the risks of antibiotic ADEs could help reduce unnecessary prescribing. Prevention efforts could target pediatric patients who are at the greatest risk of harm., (Published by Oxford University Press on behalf of The Journal of the Pediatric Infectious Diseases Society 2018.)

Introduction: National data on morbidity from nonmedical use of pharmaceuticals are limited. This study used nationally representative, public health surveillance data to characterize U.S. emergency department visits for acute harms from nonmedical use of pharmaceuticals and to guide prevention efforts., Methods: Data collected in 2016 from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project were analyzed in 2018 to calculate national estimates of emergency department visits for harms from nonmedical use of pharmaceuticals., Results: Based on 5,130 surveillance cases, there were an estimated 358,247 emergency department visits (95% CI=280,675, 435,819) in 2016 for harms from nonmedical use of pharmaceuticals and 41.1% resulted in hospitalization (95% CI=32.3%, 49.8%). One half (50.9%, 95% CI=46.6%, 55.3%) of estimated visits involved patients aged ≤34 years; more than one half of estimated visits also involved non-pharmaceutical substances (52.9%, 95% CI=49.7%, 56.1%), including illicit drugs in 34.1% (95% CI=30.9%, 37.2%) and alcohol in 21.8% (95% CI=19.8%, 23.9%). Overall, benzodiazepines were implicated in 46.9% (95% CI=42.5%, 51.2%) of estimated emergency department visits for nonmedical use of pharmaceuticals but were the only substance implicated in just 6.5% (95% CI=5.1%, 7.9%). Prescription opioids were implicated in 36.2% (95% CI=30.8%, 41.7%) of estimated emergency department visits and were the only substance implicated in 11.3% (95% CI=8.6%, 14.0%)., Conclusions: Although prescription opioids or benzodiazepines are frequently implicated in emergency department visits for nonmedical use, because other substances and additional pharmaceuticals are most often involved, prescribing clinicians should consider implementing specific screening to address polysubstance use and, when warranted, treatment interventions., (Published by Elsevier Inc.)

Objectives: To estimate the number of US emergency department visits for prescription opioid harms by patient characteristics, intent, clinical manifestations, and active ingredient., Methods: We used data from medical record-based surveillance from a nationally representative 60-hospital sample., Results: Based on 7769 cases, there were 267 020 estimated emergency department visits annually (95% confidence interval [CI] = 209 833, 324 206) for prescription opioid harms from 2016 to 2017. Nearly half of visits (47.6%; 95% CI = 40.8%, 54.4%) were attributable to nonmedical opioid use, 38.9% (95% CI = 32.9%, 44.8%) to therapeutic use, and 13.5% (95% CI = 11.0%, 16.0%) to self-harm. Co-implication with other pharmaceuticals and concurrent illicit drug and alcohol use were common; prescription opioids alone were implicated in 31.5% (95% CI = 27.2%, 35.8%) of nonmedical use visits and 19.7% (95% CI = 15.7%, 23.7%) of self-harm visits. Unresponsiveness or cardiorespiratory failure (30.0%) and altered mental status (35.7%) were common in nonmedical use visits. Gastrointestinal effects (30.4%) were common in therapeutic use visits. Oxycodone was implicated in more than one third of visits across intents., Conclusions: Morbidity data can help target interventions, such as dispensing naloxone to family and friends of those with serious overdose, and screening and treatment of substance use disorder when opioids are prescribed long-term.

Introduction: Unintentional medication ingestions by young children lead to nearly 60,000 emergency department visits annually; 15% involve oral liquid medications. Safety packaging improvements have been shown to limit liquid medication ingestions. Estimated rates of emergency department visits for pediatric ingestions by product were calculated to help target interventions., Methods: Frequencies and rates of emergency department visits for unintentional pediatric ingestions were estimated using adverse event data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project and retail sales/pharmacy dispensing data from Information Resources, Inc. and QuintilesIMS (collected 2012-2015; analyzed 2017). Rates of emergency department visits for ingestions of over-the-counter liquid medications were compared with those for prescription solid medications., Results: From the results of 568 cases, an estimated 6,427 emergency department visits (95% CI=4,907, 7,948) were made annually after a child aged <6 years accessed one of the four most commonly implicated over-the-counter liquid medications without caregiver oversight. Nearly two thirds (63.8%) of these visits were made by children aged ≤2 years and 9.0% resulted in hospitalization. Acetaminophen was the most commonly implicated over-the-counter liquid medication (2,515 estimated emergency department visits annually). Rates of emergency department visits for liquid diphenhydramine and acetaminophen ingestions (8.1 and 7.4 emergency department visits per 100,000 bottles sold) were higher than rates for other common over-the-counter liquids and comparable to high-rate prescription solid medications (clonidine and buprenorphine/naloxone: 11.1 and 10.5 emergency department visits per 100,000 dispensed prescriptions, respectively)., Conclusions: Product-specific rates of emergency department visits for unintentional ingestions can help prioritize preventive interventions, such as enhancing safety packaging with flow restrictors., (Published by Elsevier Inc.)

Background: Detailed, nationally representative data describing high-risk populations and circumstances involved in antibiotic adverse events (AEs) can inform approaches to prevention., Objective: Describe US burden, rates, and characteristics of emergency department (ED) visits by adults for antibiotic AEs., Design: Nationally representative, public health surveillance of adverse drug events (National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance [NEISS-CADES]) and a nationally projected database of dispensed prescriptions (QuintilesIMS), 2011-2015., Patients: Antibiotic-treated adults (≥ 20 years) seeking ED care., Main Measures: Estimated annual numbers and rates of ED visits for antibiotic AEs among outpatients treated with systemically administered antibiotics., Key Results: Based on 10,225 cases, US adults aged ≥ 20 years made an estimated 145,490 (95% confidence interval, 115,279-175,701) ED visits for antibiotic AEs each year in 2011-2015. Antibiotics were implicated in 13.7% (12.3-15.2%) of all estimated adult ED visits for adverse drug events. Most (56.6%; 54.8-58.4%) antibiotic AE visits involved adults aged < 50 years, and 71.8% (70.4-73.1%) involved females. Accounting for prescriptions dispensed from retail and long-term care pharmacies, adults aged 20-34 years had twice the estimated rate of ED visits for oral antibiotic AEs compared with those aged ≥ 65 years (9.7 [7.6-11.8] versus 4.6 [3.6-5.7] visits per 10,000 dispensed prescriptions, respectively). Allergic reactions accounted for three quarters (74.3%; 70.0-78.6%) of estimated ED visits for antibiotic AEs. The three most frequently implicated antibiotic classes in ED visits for antibiotic AEs were oral sulfonamides (23.2%; 20.6-25.8%), penicillins (20.8%; 19.3-22.4%), and quinolones (15.7%; 14.2-17.1%). Per-prescription rates declined with increasing age group., Conclusions: Antibiotics are a common cause of ED visits by adults for adverse drug events and represent an important safety issue. Quantifying risks of AEs from specific antibiotics for specific patient populations, such as younger adults, provides additional information to help clinicians assess risks versus benefits when making the decision to prescribe or not prescribe an antibiotic. AE rates may also facilitate communication with patients about antibiotic risks.

Introduction: To prevent errors, health care professional and safety organizations recommend using milliliters (mL) alone for oral liquid medication dosing instructions and devices. In 2018, for federal incentives under the Quality Payment Program, one requirement is for electronic health records to automatically use mL alone whenever oral liquid medications are prescribed. Current perceptions and practices of primary care providers (PCPs) regarding dosing units for oral liquid medications were assessed., Methods: Pediatricians, family practitioners, nurse practitioners, and internists participating in the 2015 DocStyles Web-based survey were asked about their perceptions and practices regarding dosing units for oral liquid medications., Results: Three fifths of PCPs (59.0%) reported that using mL alone is safest for dosing oral liquid medications; however, nearly three quarters (72.0%) thought that patients/caregivers prefer instructions that include spoon-based units. Within each specialty, fewer PCPs reported they would prescribe using mL alone than reported that using mL alone is safest (P < .0001 for all). Among PCPs who think milliliter-only dosing is safest, those who perceived patients/caregivers prefer including spoon-based units were less likely to prescribe using mL alone (odds ratio 0.45, 95% confidence interval 0.34-0.59). Pediatricians were more likely than other PCPs to report that it is safest to use mL alone (80.8% vs 54.7%) and that they would use mL alone when prescribing (56.8% vs 30.9%) (P < .0001 for both)., Conclusions: Because less than two thirds of pediatricians and one third of other PCPs would use mL alone in dosing instructions, additional education to encourage prescribing and communicating with patients/caregivers using mL alone may be needed., (Published by Elsevier Inc.)

Importance: The Patient Protection and Affordable Care Act of 2010 brought attention to adverse drug events in national patient safety efforts. Updated, detailed, nationally representative data describing adverse drug events can help focus these efforts., Objective: To describe the characteristics of emergency department (ED) visits for adverse drug events in the United States in 2013-2014 and describe changes in ED visits for adverse drug events since 2005-2006., Design, Setting, and Participants: Active, nationally representative, public health surveillance in 58 EDs located in the United States and participating in the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project., Exposures: Drugs implicated in ED visits., Main Outcomes and Measures: National weighted estimates of ED visits and subsequent hospitalizations for adverse drug events., Results: Based on data from 42 585 cases, an estimated 4.0 (95% CI, 3.1-5.0) ED visits for adverse drug events occurred per 1000 individuals annually in 2013 and 2014 and 27.3% (95% CI, 22.2%-32.4%) of ED visits for adverse drug events resulted in hospitalization. An estimated 34.5% (95% CI, 30.3%-38.8%) of ED visits for adverse drug events occurred among adults aged 65 years or older in 2013-2014 compared with an estimated 25.6% (95% CI, 21.1%-30.0%) in 2005-2006; older adults experienced the highest hospitalization rates (43.6%; 95% CI, 36.6%-50.5%). Anticoagulants, antibiotics, and diabetes agents were implicated in an estimated 46.9% (95% CI, 44.2%-49.7%) of ED visits for adverse drug events, which included clinically significant adverse events, such as hemorrhage (anticoagulants), moderate to severe allergic reactions (antibiotics), and hypoglycemia with moderate to severe neurological effects (diabetes agents). Since 2005-2006, the proportions of ED visits for adverse drug events from anticoagulants and diabetes agents have increased, whereas the proportion from antibiotics has decreased. Among children aged 5 years or younger, antibiotics were the most common drug class implicated (56.4%; 95% CI, 51.8%-61.0%). Among children and adolescents aged 6 to 19 years, antibiotics also were the most common drug class implicated (31.8%; 95% CI, 28.7%-34.9%) in ED visits for adverse drug events, followed by antipsychotics (4.5%; 95% CI, 3.3%-5.6%). Among older adults (aged ≥65 years), 3 drug classes (anticoagulants, diabetes agents, and opioid analgesics) were implicated in an estimated 59.9% (95% CI, 56.8%-62.9%) of ED visits for adverse drug events; 4 anticoagulants (warfarin, rivaroxaban, dabigatran, and enoxaparin) and 5 diabetes agents (insulin and 4 oral agents) were among the 15 most common drugs implicated. Medications to always avoid in older adults according to Beers criteria were implicated in 1.8% (95% CI, 1.5%-2.1%) of ED visits for adverse drug events., Conclusions and Relevance: The prevalence of emergency department visits for adverse drug events in the United States was estimated to be 4 per 1000 individuals in 2013 and 2014. The most common drug classes implicated were anticoagulants, antibiotics, diabetes agents, and opioid analgesics.

Expanding access to office-based medication-assisted treatment with buprenorphine/naloxone for opioid dependence is a key part of the national strategy to address the opioid abuse epidemic (1). However, as buprenorphine/naloxone prescribing increased, emergency department (ED) visits and hospitalizations for unsupervised ingestions by young children began to increase, with buprenorphine/naloxone ingestions becoming the most common cause of hospitalization for medication ingestions by young children during 2010-2011 (2). Buprenorphine ingestions might be asymptomatic or can cause drowsiness, vomiting, or respiratory depression, which if untreated can result in death (3). Buprenorphine/naloxone was available only as tablets in multidose child-resistant bottles (Suboxone) until late 2010, when film strips packaged in unit-dose, child-resistant pouches were introduced. In 2013, tablets became available in unit-dose packaging (Zubsolv). Because unit-dose, child-resistant packaging encloses each dose until opened, it might limit unintended ingestions by young children compared with traditional child-resistant bottles that must be resecured after every use (4). This study compared ED visits for pediatric buprenorphine/naloxone ingestions before and after these product packaging/formulation changes.

Background: Dietary supplements, such as herbal or complementary nutritional products and micronutrients (vitamins and minerals), are commonly used in the United States, yet national data on adverse effects are limited., Methods: We used nationally representative surveillance data from 63 emergency departments obtained from 2004 through 2013 to describe visits to U.S. emergency departments because of adverse events related to dietary supplements., Results: On the basis of 3667 cases, we estimated that 23,005 (95% confidence interval [CI], 18,611 to 27,398) emergency department visits per year were attributed to adverse events related to dietary supplements. These visits resulted in an estimated 2154 hospitalizations (95% CI, 1342 to 2967) annually. Such visits frequently involved young adults between the ages of 20 and 34 years (28.0% of visits; 95% CI, 25.1 to 30.8) and unsupervised children (21.2% of visits; 95% CI, 18.4 to 24.0). After the exclusion of unsupervised ingestion of dietary supplements by children, 65.9% (95% CI, 63.2 to 68.5) of emergency department visits for single-supplement-related adverse events involved herbal or complementary nutritional products; 31.8% (95% CI, 29.2 to 34.3) involved micronutrients. Herbal or complementary nutritional products for weight loss (25.5%; 95% CI, 23.1 to 27.9) and increased energy (10.0%; 95% CI, 8.0 to 11.9) were commonly implicated. Weight-loss or energy products caused 71.8% (95% CI, 67.6 to 76.1) of supplement-related adverse events involving palpitations, chest pain, or tachycardia, and 58.0% (95% CI, 52.2 to 63.7) involved persons 20 to 34 years of age. Among adults 65 years of age or older, choking or pill-induced dysphagia or globus caused 37.6% (95% CI, 29.1 to 46.2) of all emergency department visits for supplement-related adverse events; micronutrients were implicated in 83.1% (95% CI, 73.3 to 92.9) of these visits., Conclusions: An estimated 23,000 emergency department visits in the United States every year are attributed to adverse events related to dietary supplements. Such visits commonly involve cardiovascular manifestations from weight-loss or energy products among young adults and swallowing problems, often associated with micronutrients, among older adults. (Funded by the Department of Health and Human Services.).

Background: After reports of increasing emergency department (ED) visits for unsupervised pediatric medication exposures in the 2000s, renewed efforts to improve safety packaging and education were initiated. National data on current trends can help further target interventions., Methods: We used nationally representative data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project (2004-2013) to assess trends in ED visits for unsupervised medication exposures in children aged <6 years. For 2010 through 2013, the dosage form and prescription status of implicated medications were identified., Results: Based on 13,268 cases, there were an estimated 640,161 ED visits (95% confidence interval: 512,885 to 767,436) for unsupervised medication exposures from 2004 through 2013. From 2004 through 2010, ED visits for unsupervised exposures increased by an average of 5.7% annually, peaking at 75,842. After 2010, this trend reversed, and visits decreased by an average of 6.7% annually to 59,092 in 2013. From 2010 through 2013, 91.0% of unsupervised exposure visits involved 1 medication, most commonly an oral prescription solid (45.9%), oral over-the-counter (OTC) solid (22.3%), or oral OTC liquid (12.4%). More than 260 different prescription solids were implicated; opioids (13.8%) and benzodiazepines (12.7%) were the most common classes. Four medications were implicated in 91.2% of OTC liquid exposure visits: acetaminophen (32.9%), cough and cold remedies (27.5%), ibuprofen (15.7%), and diphenhydramine (15.6%)., Conclusions: Targeting prevention efforts based on harm frequency and intervention feasibility can lead to continued reductions in ED visits for pediatric medication exposures., (Copyright © 2015 by the American Academy of Pediatrics.)

Background: Emergency department visits and subsequent hospitalizations of young children after unsupervised ingestions of prescription medications are increasing despite widespread use of child-resistant packaging and caregiver education efforts. Data on the medications implicated in ingestions are limited but could help identify prevention priorities and intervention strategies., Methods: We used nationally representative adverse drug event data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project and national retail pharmacy prescription data from IMS Health to estimate the frequency and rates of emergency hospitalizations for unsupervised prescription medication ingestions by young children (2007-2011)., Results: On the basis of 1513 surveillance cases, 9490 estimated emergency hospitalizations (95% confidence interval: 6420-12,560) occurred annually in the United States for unsupervised prescription medication ingestions among children aged <6 years from 2007 through 2011; 75.4% involved 1- or 2-year old children. Opioids (17.6%) and benzodiazepines (10.1%) were the most commonly implicated medication classes. The most commonly implicated active ingredients were buprenorphine (7.7%) and clonidine (7.4%). The top 12 active ingredients, alone or in combination with others, were implicated in nearly half (45.0%) of hospitalizations. Accounting for the number of unique patients who received dispensed prescriptions, the hospitalization rate for unsupervised ingestion of buprenorphine products was significantly higher than rates for all other commonly implicated medications and 97-fold higher than the rate for oxycodone products (200.1 vs 2.1 hospitalizations per 100,000 unique patients)., Conclusions: Focusing unsupervised ingestion prevention efforts on medications with the highest hospitalization rates may efficiently achieve large public health impact., (Copyright © 2014 by the American Academy of Pediatrics.)

Importance: Detailed, nationally representative data describing high-risk populations and circumstances involved in insulin-related hypoglycemia and errors (IHEs) can inform approaches to individualizing glycemic targets., Objective: To describe the US burden, rates, and characteristics of emergency department (ED) visits and emergency hospitalizations for IHEs., Design, Setting, and Participants: Nationally representative public health surveillance of adverse drug events among insulin-treated patients seeking ED care (National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project) and a national household survey of insulin use (the National Health Interview Survey) were used to obtain data from January 1, 2007, through December 31, 2011., Main Outcomes and Measures: Estimated annual numbers and estimated annual rates of ED visits and hospitalizations for IHEs among insulin-treated patients with diabetes mellitus., Results: Based on 8100 National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance cases, an estimated 97,648 (95% CI, 64,410-130,887) ED visits for IHEs occurred annually; almost one-third (29.3%; 95% CI, 21.8%-36.8%) resulted in hospitalization. Severe neurologic sequelae were documented in an estimated 60.6% (95% CI, 51.3%-69.9%) of ED visits for IHEs, and blood glucose levels of 50 mg/dL (to convert to millimoles per liter, multiply by 0.0555) or less were recorded in more than half of cases (53.4%). Insulin-treated patients 80 years or older were more than twice as likely to visit the ED (rate ratio, 2.5; 95% CI, 1.5-4.3) and nearly 5 times as likely to be subsequently hospitalized (rate ratio, 4.9; 95% CI, 2.6-9.1) for IHEs than those 45 to 64 years. The most commonly identified IHE precipitants were reduced food intake and administration of the wrong insulin product., Conclusions and Relevance: Rates of ED visits and subsequent hospitalizations for IHEs were highest in patients 80 years or older; the risks of hypoglycemic sequelae in this age group should be considered in decisions to prescribe and intensify insulin. Meal-planning misadventures and insulin product mix-ups are important targets for hypoglycemia prevention efforts.

Objective: To reduce dosing errors when administering orally ingested over-the-counter liquid medications, the US Food and Drug Administration (FDA) and the Consumer Healthcare Products Association released voluntary recommendations for dosing directions and dosing devices. This study assessed recommendation adherence for national brand name orally ingested over-the-counter liquid pediatric analgesics/antipyretics and cough, cold, and allergy medications available after the FDA guidance was finalized in 2011 to identify and prioritize specific improvements to dosing directions and devices., Methods: Recommendations were categorized as top tier or low tier based on potential to directly address ≥3-fold dosing errors. Two independent reviewers assessed dosing directions and accompanying dosing devices for adherence to recommendations., Results: Of 68 products, 91% of dosing directions and 62% of dosing devices adhered to all top tier recommendations; 57% of products adhered to every top tier recommendation, and 93% adhered to all or all but one. A dosing device was included with all products. No dosing directions used atypical volumetric units (eg, drams), and no devices used volumetric units that did not appear in dosing directions. Six products used trailing zeros or failed to use leading zeros with decimal doses; eight did not use small font for fractions. Product adherence to low tier recommendations ranged from 26% to 91%., Conclusions: Products adhered to most recommendations in the final FDA guidance and Consumer Healthcare Products Association guideline, suggesting that these voluntary initiatives promote adherence to recommendations. Improving adherence to recommendations should be prioritized based on potential to reduce harm.

Objective: To assess whether adding flow restrictors (FRs) to liquid medicine bottles can provide additional protection against unsupervised medication ingestions by young children, even when the child-resistant closure is not fully secured., Study Design: In April and May 2012, we conducted a block randomized trial with a convenience sample of 110 3- and 4-year-old children from 5 local preschools. Participants attempted to remove test liquid from an uncapped bottle with an FR and a control bottle without an FR (with either no cap or an incompletely closed cap)., Results: All but 1 (96%; 25 of 26) of the open control bottles and 82% (68 of 83) of the incompletely closed control bottles were emptied within 2 minutes. Only 6% (7 of 110) of the bottles with FRs were emptied during the 10-minute testing period, none before 6 minutes. Overall, children removed less liquid from the bottles with FRs than from the open or incompletely closed control bottles without FRs (both P < .001). All children assigned open control bottles and 90% of those assigned incompletely closed control bottles removed ≥ 25 mL of liquid. In contrast, 11% of children removed ≥ 25 mL of liquid from uncapped bottles with FRs. Older children (aged 54-59 months) were more successful than younger children at removing ≥ 25 mL of liquid (P = .002) from bottles with FRs., Conclusion: Our findings suggest that adding FRs to liquid medicine bottles limits the accessibility of their contents to young children and could complement the safety provided by current child-resistant packaging., (Published by Mosby, Inc.)

Background: Adverse drug events are important preventable causes of hospitalization in older adults. However, nationally representative data on adverse drug events that result in hospitalization in this population have been limited., Methods: We used adverse-event data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project (2007 through 2009) to estimate the frequency and rates of hospitalization after emergency department visits for adverse drug events in older adults and to assess the contribution of specific medications, including those identified as high-risk or potentially inappropriate by national quality measures., Results: On the basis of 5077 cases identified in our sample, there were an estimated 99,628 emergency hospitalizations (95% confidence interval [CI], 55,531 to 143,724) for adverse drug events in U.S. adults 65 years of age or older each year from 2007 through 2009. Nearly half of these hospitalizations were among adults 80 years of age or older (48.1%; 95% CI, 44.6 to 51.6). Nearly two thirds of hospitalizations were due to unintentional overdoses (65.7%; 95% CI, 60.1 to 71.3). Four medications or medication classes were implicated alone or in combination in 67.0% (95% CI, 60.0 to 74.1) of hospitalizations: warfarin (33.3%), insulins (13.9%), oral antiplatelet agents (13.3%), and oral hypoglycemic agents (10.7%). High-risk medications were implicated in only 1.2% (95% CI, 0.7 to 1.7) of hospitalizations., Conclusions: Most emergency hospitalizations for recognized adverse drug events in older adults resulted from a few commonly used medications, and relatively few resulted from medications typically designated as high-risk or inappropriate. Improved management of antithrombotic and antidiabetic drugs has the potential to reduce hospitalizations for adverse drug events in older adults.

Purpose: To estimate the number of acetaminophen overdose-related emergency department (ED) visits and hospitalizations in the United States, characterize these by intentionality, age, and gender, and compare the strengths and limitations of the utilized databases., Methods: We used data from the National Hospital Ambulatory Medical Care Survey (NHAMCS) and the National Electronic Injury Surveillance System (NEISS) to estimate the number of relevant ED visits in the United States between 2000 and 2007, and the National Hospital Discharge Survey (NHDS) to estimate the number of relevant hospitalizations in the United States between 1991 and 2006. National estimates and their standard errors were calculated using information provided in each database. We used the standard United States population in 2000 to calculate age-adjusted rates., Results: We estimate an annual average of 44,348 (NHAMCS, 2000-2007) or 78,414 (NEISS, 2006-2007) acetaminophen overdose-related ED visits and 33,520 (NHDS, 2000-2006) hospitalizations. For 2000-2006 we calculated an age-adjusted rate of 13.9 acetaminophen overdose-related hospitalizations per 100,000 US population, with the highest rate (15.7) occurring from 2005 to 2006. Between 1991 and 2006, there was no decrease noted in hospitalizations for intentional or unintentional overdoses. The majority of overdoses reported in NEISS (69.8%) and NHDS (74.2%) were classified as intentional (suicides or suicidal gestures), whereas in NHAMCS, intentionality was evenly distributed., Conclusions: Our results suggest that acetaminophen overdose, both intentional and unintentional, remains a significant public health concern. With an understanding of their methodological characteristics and limitations, these national databases can be useful tools to characterize acetaminophen overdose-related ED visits and hospitalizations., (Published in 2011 by John Wiley & Sons, Ltd.)

Background: Limited national data on the circumstances of acetaminophen overdoses have hindered identification and implementation of prevention strategies., Purpose: To estimate the frequency of and characterize risks for emergency department visits for acetaminophen overdoses that were not related to abuse in the U.S., Methods: Data were collected from two components of the National Electronic Injury Surveillance System from January 1, 2006, through December 31, 2007, and analyzed from 2009 to 2010 to estimate the annual number of emergency department visits for non-abuse-related acetaminophen overdose by patient demographics, treatments, and type and amount of acetaminophen-containing product ingested., Results: There were an estimated 78,414 emergency department visits (95% CI=63655, 93172) annually for non-abuse-related overdoses of acetaminophen-containing products. Most emergency department visits for acetaminophen overdose were for self-directed violence (69.8%, 95% CI=66.4%, 73.2%), with the highest rate among patients aged 15-24 years (46.4 per 100,000 individuals per year). Unsupervised ingestions by children aged <6 years accounted for 13.4% (95% CI=11.0%, 15.9%) of visits for acetaminophen overdoses (42.5 per 100,000 individuals per year). Therapeutic misadventures accounted for 16.7% (95% CI=14.0%, 19.5%) of visits and most involved overuse for medicinal effects (56.1%, 95% CI=50.6%, 61.6%) rather than use of multiple acetaminophen-containing products or dose confusion., Conclusions: Non-abuse-related overdoses of acetaminophen products lead to many emergency department visits each year, particularly emergency department visits for self-directed violence. Acetaminophen overdose prevention efforts will likely need to be multidimensional., (Published by Elsevier Inc.)

The 2009 pandemic influenza A (H1N1) outbreak was associated with an increased use of antiviral agents and highlighted the role of population-based monitoring for related adverse drug events (ADEs). An ongoing, nationally representative emergency department-based surveillance system was used to identify and characterize ADEs during the pandemic. Active surveillance for ADEs successfully provided timely, population-based data during the pandemic. Increases in antiviral ADEs paralleled increases in prescribing. Type and severity of ADEs were similar across all seasons.

BACKGROUND: In the global program for the elimination of lymphatic filariasis (LF) longitudinal assessment of the prevalence of microfilaremia and antigenemia is recommended to monitor the effect of mass treatment on transmission. Additional monitoring tools such as entomologic and antibody methods may be useful in identifying residual foci of infection. In this study, we characterized serologic markers of infection and exposure spatially both before and after mass treatment, in an area of initial low Wuchereria bancrofti infection prevalence. METHODS: Consenting persons in the sentinel community were tested for circulating microfilaria and antigen (by immunochromatographic test) before and after the 1st annual mass drug administration of diethylcarbamazine and albendazole. A cohort of 161 persons provided serum specimens both years that were tested for antifilarial IgG (1 and 4) antibody. Every house was mapped using a differential Global Positioning System; this information was linked to the serologic data. W. bancrofti infection in the mosquito vector was assessed with year-round collection. Multiple linear regression was used to investigate the influence of antigen-positive persons on the antifilarial antibody responses of antigen-negative neighbors. RESULTS: After mass treatment, decreases were observed in the sentinel site in the overall prevalence of antigen (10.4% to 6.3%) and microfilaremia (0.9 to 0.4%). Of the persons in the cohort that provided serum specimens both years, 79% received treatment. Antigen prevalence decreased from 15.0% to 8.7%. Among 126 persons who received treatment, antigen and antifilarial IgG1 prevalence decreased significantly (p = 0.002 and 0.001, respectively). Among 34 persons who did not receive treatment, antifilarial IgG1 prevalence increased significantly (p = 0.003). Average antifilarial IgG1 levels decreased in households with high treatment coverage and increased in households that refused treatment. Each 10-meter increase in distance from the residence of a person who was antigen-positive in 2000 was associated a 4.68 unit decrease in antifilarial IgG1 level in 2001, controlling for other factors (p = 0.04). DISCUSSION: Antifilarial antibody assays can be used as a measure of filarial exposure. Our results suggest that micro-scale spatial heterogeneity exists in LF exposure and infection. Treatment appeared to be associated with reduced exposure at the sub-community level, suggesting the need to achieve high and homogeneous coverage. Public health messages should note the benefits of having one's neighbors receive treatment with antifilarial drugs.