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This is the first study to examine population medication prescription rates among U.S. submariners by common therapeutic classifications.Individual-level pharmacy records during the years 2007 to 2018 were extracted from the Military Health System's Pharmacy Data Transaction Service (PDTS) file. Demographic and military factors captured from Navy personnel files were linked to PDTS records. Logistic regression models were used to identify characteristics and trends associated with prevalence. Published total rates for other active-duty components were compared to submariner rates.There were data for 50,720 submariners, among whom 576,782 prescriptions were filled. Prevalence rates decreased significantly from 2007-2018 among most drug classes. Central nervous system agents accounted for 31% of the total prescriptions, followed by 12% for eye, ear, nose, and throat preparations, and 10% for anti-infective agents. Higher prescription rates were associated with being enlisted, younger, a woman, lower-ranked, or Hispanic. The mean yearly prescription rate was 2.7 per submariner, less than half of the overall rate of all military components.The survival benefit of HBO2 therapy observed in our unadjusted analysis suggests that there may be therapeutic benefits of HBO2 in treating COVID-19 hypoxia as an adjunct to standard care.

IntroductionMaintaining healthy, well-trained, and highly qualified armed forces is critical for ensuring military readiness. The purpose of this article is to contribute to the body of research focused on the health of U.S. Navy submariners and to identify the health conditions of U.S. Navy submariners during their final year of active duty service.Materials and MethodsIn this retrospective cohort study, we examined medical records and personnel files of separating U.S. Navy sailors who were: (1) active duty between 2009 and 2018; (2) separated before 2019; and (3) were assigned to a submarine for at least 30 days. Both officers and enlisted service members were included. We linked, described, and analyzed data from the Defense Health Agency, Military Health System Data Repository (MDR), and the Bureau of Naval Personnel (BUPERS). International Classification of Diseases (ICD) diagnoses codes were obtained from MDR. Data collected from BUPERS include age, sex, and rank. We determined the number of individuals who had at least one diagnosed condition (identified as a three-digit ICD code). We report the number of diagnoses and calculate prevalence rates and confidence intervals per condition, as well as prevalence rates per year, using standard formulas. The study was approved by the Naval Submarine Medical Research Laboratory Institutional Review Board.ResultsDuring the study period, 26,014 submariners separated from the Navy. The average number of separations per year was 2,601. About a third of the separating submariners were in the 25 to 29 age group and over 50% were under 30 years of age. Of the three-digit individual ICD codes, some of the highest operationally relevant rates over the 10-year study period (2009-2018) were for joint disorders (prevalence rate [PR] = 180 per 1,000 submariners), back disorders (PR = 128), and sleep disorders (PR = 134). Three mental-health-related conditions were also among the 20 conditions with the highest rates.ConclusionsHigh rates of specific diagnoses such as joint disorders indicate the need for additional study to examine causal relationships, to determine which conditions may contribute to lost work time, early separations, or low rates of reenlistment and which conditions might be a result of specific military occupations or duties. Study strengths are the large number of subjects and the long period of observations. A study weakness was the inability to identify submariners who separated because of health conditions. The overall impact of the study is that it identifies urgent health risks and establishes a way to prioritize future research. Future research should include a focus on medically separated personnel; compare rates for submariners to other military groups including all-Navy and all-Department of Defense; and determine specific and relative risks as a necessary precursor to developing, implementing, and testing risk reduction and health improvement interventions.

To identify the most prevalent health conditions among divers during their last year of Navy service.For this retrospective descriptive study we used data from the Dive Jump Reporting System to identify 4,623 active-duty divers who separated between 2008 and 2018. Medical records, dive histories, and personnel files were merged, linked and analyzed at the individual level.On average, 420 divers separated each year. Among the separating divers, 99% were male, 26% were aged 25 to 29 years old with a mean age of 35 (SD = 9, range 18 to 65). The major medical categories with the highest numbers of divers affected were: musculoskeletal system diseases (prevalence rate (PR) = 515.2 per 1,000 divers/year); nervous system (PR = 411.9); injury and poisonings (PR = 249.8); and mental disorders (PR = 237.3). Of the 50 specific conditions that affected the most divers the top four were joint disorders (PR = 34.5), disorders of refraction and accommodation (PR = 30.1), back disorders (PR = 26.8) and organic sleep disorders (PR = 21.6). Compared to divers with fewer than 29 dives, divers with 49-plus dives were about twice as likely to have diagnoses related to symptoms involving head and neck.The study found high rates of conditions such as musculoskeletal disorders, joint and back disorders, and some mental health related disorders. Special warfare divers have high rates of hearing loss, and other disorders of ear. The results show the need and to develop and implement group-specific mitigation programs.

Objectives To investigate the change in hearing and perceived comfort over 1 year related to using an active hearing protection device (HPD) among United States Marine Corps (USMC) personnel routinely exposed to hazardous noise. Methods USMC Weapons Instructors (n = 127) were issued an active earmuff that met military standards and was compatible with other protective equipment. These participants completed pre- and post-hearing tests and comfort surveys. A control cohort (n = 94) was also included to compare individual changes in high-frequency pure tone average (HF-PTA) over 1 year. Results The control group’s HF-PTA was 3 dB worse than the intervention group after only 1 year. Survey responses revealed perceived improvements in the ability to hear and understand, situational awareness, and safety. Conclusions Active HPDs can reduce hearing loss and improve hearing-related occupational tasks.

Pressurized Submarine Escape Training (PSET) physically prepares submariners to safely escape a submarine at depth. Failure to complete PSET is not a submarine service disqualification. Serious medical incidents are rare, but the safety record tradeoff has been low throughput. From 2009 to 2015, only 34% of students screened completed PSET. Students may be medically screened out of the training altogether (disqualified), or dropout during the physical training (attrite). Training records from 12,122 U.S. Navy students were used to identify factors contributing to training disqualification and attrition. Multivariate logistic regression model predictors included demographic and screening items. Association to PSET disqualification included cold/congestion/cough (ORadj 12.34), limited duty status (ORadj 4.29), Physical Readiness Test failure (ORadj 3.37), pneumonia or bronchitis in last 2 years (ORadj 3.17) and nervousness or anxiety in tight spaces (ORadj 2.37). Basic Enlisted Submarine School students were more likely to be disqualified and attrite than other submariner groups, and black/African American (ORadj 1.53) students were more likely to attrite than white students. Only cold/congestion/cough (ORadj 1.52), trouble swimming (ORadj 1.53), and screening during cold/flu season (ORadj 1.28), were associated with training attrition. Recommendations to modify screening requirements are listed in conclusions.

To evaluate the effectiveness of the US Navy and Marine Corps tobacco policy in protecting submariners from secondhand smoke (SHS) by determining if non-tobacco users experienced a significant increase in urinary cotinine levels at sea when compared with in port levels.From February to August 2009, 634 volunteers recruited from nine US Navy submarines completed a survey to collect demographic data, information on tobacco use and pre-deployment exposure to SHS. Non-tobacco users (n=239) were requested to provide two urine samples (pre-deployment and while at sea) to quantify exposure to SHS using urinary cotinine as a biomarker. Matched samples were analysed using liquid chromatography-tandem mass spectrometry.Overall, deployed cotinine levels were 2.1 times the in port levels in non-tobacco using submariners (95% CI 1.8 to 2.4, p0.001, n=197). A significant increase in deployed urinary cotinine levels was found aboard six of nine submarines (p0.05). A subgroup of submariners (n=91) who reported no SHS exposure within 10 days prior to in port cotinine sampling had deployed cotinine levels 2.7 times the in port levels (95% CI 2.2 to 3.3, p0.001). Applying a 4.5:1 urine cotinine to serum cotinine correction factor, submariners' deployed geometric means are similar to recent US male population values at the 75th percentile.This study provides evidence that non-tobacco using submariners were exposed to SHS. Exposure was seen in all submarine classes and was not limited to personnel working in proximity to the smoking area. The existing policy was inadequate to protect non-smokers from exposure to SHS and required revision. As a result of a policy review, informed by this study, smoking below decks was banned aboard all US Navy submarines effective 31 December 2010.

Middle ear barotrauma (MEBT) is the most common medical complication in diving, aviation, and hyperbaric medicine. Eustachian tube dysfunction (ETD) quantifies the inability to open the eustachian tube (ET), risking MEBT. Surfactant administration improved ET function and efficaciously treated otitis media in a host of animal models. We performed a pilot study evaluating the efficacy of intranasal surfactant administration in reducing MEBT in repetitive diving.Eight divers participated in a subject-blinded, placebo-controlled, random order, multiarm (air and O2)-repeated measures trial investigating the relative efficacy of intranasally administered surfactant, acetylcysteine and oxymetazoline, and orally administered pseudoephedrine versus saline-placebo in middle ear equilibration during repetitive, multiday diving. Subjects were tested with the Nine-Step Inflation/Deflation Tympanometry Test (NSI/DT) and sonotubometry (testing eustachian tube opening pressure [ETOP]) before and immediately after each dive.Significant interaction effects were found for drug-by-test (F8,668 = 4.05; p0.001) and the three-way interaction of drug-by-dive-by-test (F16,668 = 2.47; p = 0.001) in sonotubometry testing. The ETOP revealed trends toward lowered (improved) values post-versus predive in all treatment arms, which was significant for oxymetazoline (p = 0.04). Only four of the eight subjects experienced any holds during diving. Statistical analysis of the NSI/DT data showed that none of the drug interventions resulted in improvements in ET function over that expected by chance.There is large intra- and intersubject variability in daily functioning of the ET as measured using the NSI/DT and sonotubomtery (ETOP). Sonotubometry engendered trends toward lowered (improved) values post-versus predive in all treatment arms. The repetitive dives did not result in a significant decrease in ET function as evidenced in the saline-placebo trials, circumventing an ability to detect superiority among the various treatment arms in our subject population. Additionally, since our study was underpowered to detect significant effects, we can only assert that various inhalational agents may improve middle ear ventilation in repetitive diving warranting further study. A larger subject population including subjects diagnosed with ET dysfunction may provide more statistical power to discern the benefit of inhaled agents as a useful prophylactic for preventing or reducing ET dysfunction during diving and/or hyperbaric/hypobaric pressure changes.

Eustachian tube dysfunction (ETD) is associated with middle-ear barotraumas, which is one of the most prevalent medical complications in diving, aviation forces, and hyperbaric medicine. The purpose of this trial was to determine the efficacy of various drugs to decrease the incidence of ETD. Acetylcysteine, surfactant, pseudoephedrine, and oxymetazoline were tested against nasal saline mist in a subject-blinded, randomized trial. Divers were administered the drugs just prior to repetitive bounce dives while breathing oxygen or air in separate trials. Effectiveness was assessed via subjective difficulty to clear (holds on descent), ET opening pressures, and measurements elicited from a 9-step inflation/deflation tympanogram. There was considerable variability in the outcomes of each analysis that resulted in no consistent differences being established between the drugs evaluated. No drug had evidence to support recommendations for or against its use in preventing ETD. Some of the drugs tested may yet show beneficence if evaluated in another experiment designed to address the confounding factors encountered during this study.

Exposure to hazardous noise results in increased reactive oxygen species (ROS) activity within the cochlea that causes damage to the outer hair cells, the result is noise-induced, sensorineural hearing loss. Evoked otoacoustic emissions (EOAEs) are an electrophysiological measure of inner ear activity that reflects cochlear outer hair cell functioning during the processing of auditory stimuli. Stimulus frequency OAE (SFOAE) have the potential to assess both the sensitivity and the tuning capabilities of the cochlea. This study assessed the sub-clinical effects of increased oxygen and/or carbon dioxide levels on inner ear processing of sound as reflected by SFOAE absolute amplitude and changes in the phase of the SFOAE response as test frequencies are increased. The results of this study indicate cochlear processing is affected by breathing higher than normal levels of oxygen and carbon dioxide, but generalization of the results is limited by the small number of subjects tested. Further research is needed with a larger sample size to determine if significant changes in SFOAE amplitudes have a harmful or protective effect on cochlear functioning.

The extent to which headaches occur among submariners and impact their performance is unknown. The objective of this survey was to evaluate headaches as an issue of concern noted during SURVIVEX 2004, a disabled submarine survival exercise conducted aboard USS SALT LAKE CITY. For four days, the subjects were exposed to carbon dioxide levels above 1.5% and oxygen levels of below 19%. Of the 73 respondents, 47.9% of the subjects experienced a headache during the exercise, with 77.1% describing the pain as severe. The incidence of headache among SURVIVEX subjects needs to be considered in disabled submarine scenario planning.

Audiometric thresholds and otoacoustic emissions (OAEs) were measured in 285 U.S. Marine Corps recruits before and three weeks after exposure to impulse-noise sources from weapons' fire and simulated artillery, and in 32 non-noise-exposed controls. At pre-test, audiometric thresholds for all ears were

In a longitudinal study with 338 volunteers, audiometric thresholds and otoacoustic emissions were measured before and after 6 months of noise exposure on an aircraft carrier. While the average amplitudes of the otoacoustic emissions decreased significantly, the average audiometric thresholds did not change. Furthermore, there were no significant correlations between changes in audiometric thresholds and changes in otoacoustic emissions. Changes in transient-evoked otoacoustic emissions and distortion-product otoacoustic emissions were moderately correlated. Eighteen ears acquired permanent audiometric threshold shifts. Only one-third of those ears showed significant otoacoustic emission shifts that mirrored their permanent threshold shifts. A Bayesian analysis indicated that permanent threshold shift status following a deployment was predicted by baseline low-level or absent otoacoustic emissions. The best predictor was transient-evoked otoacoustic emission amplitude in the 4-kHz half-octave frequency band, with risk increasing more than sixfold from approximately 3% to 20% as the emission amplitude decreased. It is possible that the otoacoustic emissions indicated noise-induced changes in the inner ear, undetected by audiometric tests. Otoacoustic emissions may therefore be a diagnostic predictor for noise-induced-hearing-loss risk.

No recent studies on Navy personnel have examined the relationship between aerobic activity and adverse health conditions or medical care visits. This study examined these relationships to determine if aerobic activity was inversely related to self- reported health conditions and medical visits. Contingency tables were computed for amount of self-reported aerobic activity and prevalence rate of adverse health conditions, number of adverse health conditions, number of medical visits, and gender. Chi-square and Fisher's exact tests were performed. Age, educational level, marital status, and gender were controlled for in some tests. Women exercised more frequently than men, and men engaged in more work-related aerobic activity days. Women also reported more health conditions, (P