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We describe our experience of an inter-university partnership among six historically Black colleges and a research university in South Carolina to address health disparities. The program offered fellowships to African American students, from high school through graduate programs, along with structured learning experiences in public health advocacy, practice, and research. [ABSTRACT FROM AUTHOR]

Objective: To carry out a community-based research approach to determine the most effective educational interventions to reduce smoking among African-American smokers. The intervention included preparation of the community, planning and developing a model of change, and developing a community-based intervention. The study population consisted of 2,544 randomly selected adult African-American smokers residing in four sites in the northeastern and southeastern parts of the United States. The research design provided a comparison of active intervention sites with passive control sites as well as low income and moderate income areas. Major Outcome Measures: Point prevalence of non-smoking at the time of interview; Period prevalence of non-smoking at the time of interview; Period prevalence of quit attempts in the prior six months; Number of smoke-free days in the prior six months; Number of cigarettes smoked daily at the time of interview. Results: Based upon a survey eighteen months after baseline data was collected, all four measures of cigarette smoking behavior showed a strong statistically significant reduction of personal smoking behavior among those receiving active interventions versus the passive group. On the basis of process variable analysis, direct contact with the project staff in the prior six months was significantly higher in the active intervention areas. There was only a small non-significant increase in personal smoking behavior in moderate income groups as opposed to low income groups. Conclusion: An analysis of process variables strongly suggests that, within this African-American Community, 'hands on' or 'face to face' approaches along with mass media, mailings, and other less personal approaches were more effective in reducing personal smoking behavior than media, mailings, and other impersonal approaches alone addressed to large audiences. [ABSTRACT FROM AUTHOR]

The associations between participation in several specific sports, use of free weights, and use of weight lifting equipment and herniated lumbar or cervical intervertebral discs were examined in a case-control epidemiologic study. Specific sports considered were baseball or softball, golf, bowling, swimming, diving, jogging, aerobics, and racquet sports. Included in the final analysis were 287 patients with lumbar disc herniation and 63 patients with cervical disc herniation, each matched by sex, source of care, and decade of age 1 control who was free of disc herniation and other conditions of the back or neck. Results indicated that most sports are not associated with an increased risk of herniation, and may be protective. Relative risk estimates for the association between individual sports and lumbar or cervical herniation were genrally less than or close to 1.0. There was, however, a weak positive association between bowling and herniation at both the lumbar and cervical regions of the spine. Use of weight lifting equipment was not associated with herniated lumbar or cervical disc, but a possible association was indicated between use of free weights and risk of cervical herniation (relative risk, 1.87; 95% confidence interval, 0.74 to 4.74). [ABSTRACT FROM AUTHOR]

Abstract Background After the Chernobyl nuclear accident on April 26, 1986, all children in the contaminated territory of the Narodichesky region, Zhitomir Oblast, Ukraine, were obliged to participate in a yearly medical examination. We present the results from these examinations for the years 1993 to 1998. Since the hematopoietic system is an important target, we investigated the association between residential soil density of 137Caesium (137Cs) and hemoglobin concentration, and erythrocyte, platelet, and leukocyte counts in 1,251 children, using 4,989 repeated measurements taken from 1993 to 1998. Methods Soil contamination measurements from 38 settlements were used as exposures. Blood counts were conducted using the same auto-analyzer in all investigations for all years. We used linear mixed models to compensate for the repeated measurements of each child over the six year period. We estimated the adjusted means for all markers, controlling for potential confounders. Results Data show a statistically significant reduction in red and white blood cell counts, platelet counts and hemoglobin with increasing residential 137Cs soil contamination. Over the six-year observation period, hematologic markers did improve. In children with the higher exposure who were born before the accident, this improvement was more pronounced for platelet counts, and less for red blood cells and hemoglobin. There was no exposure×time interaction for white blood cell counts and not in 702 children who were born after the accident. The initial exposure gradient persisted in this sub-sample of children. Conclusion The study is the first longitudinal analysis from a large cohort of children after the Chernobyl accident. The findings suggest persistent adverse hematological effects associated with residential 137Cs exposure.

OBJECTIVE: To introduce a human capital approach to reduce health disparities in South Carolina by increasing the number and quality of trained minority professionals in public health practice and research. METHODS: The conceptual basis and elements of Project EXPORT in South Carolina are described. Project EXPORT is a community based participatory research (CBPR) translational project designed to build human capital in public health practice and research. This project involves Claflin University (CU), a Historically Black College University (HBCU) and the African American community of Orangeburg, South Carolina to reduce health disparities, utilizing resources from the University of South Carolina (USC), a level 1 research institution to build expertise at a minority serving institution. The elements of Project EXPORT were created to advance the science base of disparities reduction, increase trained minority researchers, and engage the African American community at all stages of research. CONCLUSION: Building upon past collaborations between HBCU's in South Carolina and USC, this project holds promise for a public health human capital approach to reduce health disparities.

Background: After the Chernobyl nuclear accident on April 26, 1986, all children in the contaminated territory of the Narodichesky region, Zhitomir Oblast, Ukraine, were obliged to participate in a yearly medical examination. We present the results from these examinations for the years 1993 to 1998. Since the hematopoietic system is an important target, we investigated the association between residential soil density of 137Caesium (137Cs) and hemoglobin concentration, and erythrocyte, platelet, and leukocyte counts in 1,251 children, using 4,989 repeated measurements taken from 1993 to 1998., Methods: Soil contamination measurements from 38 settlements were used as exposures. Blood counts were conducted using the same auto-analyzer in all investigations for all years. We used linear mixed models to compensate for the repeated measurements of each child over the six year period. We estimated the adjusted means for all markers, controlling for potential confounders., Results: Data show a statistically significant reduction in red and white blood cell counts, platelet counts and hemoglobin with increasing residential 137Cs soil contamination. Over the six-year observation period, hematologic markers did improve. In children with the higher exposure who were born before the accident, this improvement was more pronounced for platelet counts, and less for red blood cells and hemoglobin. There was no exposurextime interaction for white blood cell counts and not in 702 children who were born after the accident. The initial exposure gradient persisted in this sub-sample of children., Conclusion: The study is the first longitudinal analysis from a large cohort of children after the Chernobyl accident. The findings suggest persistent adverse hematological effects associated with residential 137Cs exposure.

2,3,7,8-tetrachlordibenzo-p-doxin (TCDD) would not have been designated as a Group 1 carcinogen by IARC had there not been a change in the criteria used for inclusion in this category. Furthermore, there is no precedent for indicating, as did IARC, that a single chemical acts as a pluripotential carcinogen by modestly increasing human risk for all cancer while not increasing the risk for any single cancer at least moderately. IARC moved TCDD to Group 1 based on mechanistic considerations focusing on the Ah receptor. However, while occupancy of the Ah receptor by TCDD may be necessary for its toxicity, it is not sufficient for toxicity or for potential carcinogenicity. Animal evidence relating TCDD exposure to cancer is much stronger than that for humans. However, the large inter-species variation in the relevant dose-response slopes severely limits generalizations from animals to humans. The epidemiologic studies of occupational exposures, pesticide applicators, and community exposures following industrial accidents, notably Seveso, have generated overall relative risks of all cancer of about 1.0. Only case-control studies of soft-tissue sarcoma and non-Hodgkin's lymphoma, all by the same investigator, reported elevated risk from TCDD exposure. However, these results have not been replicated. The representation that a chemical compound (TCDD) would be a late-stage carcinogen for all types of cancer has no precedent and lacks biological foundation. Virtually all late-stage or promoting carcinogens (e.g., hepatitis-C virus, asbestos, and estrogens) cause a very limited number of forms of cancer. The exposure-response meta-analysis of TCDD and cancer developed by the United States Environmental Protection Agency (USEPA) is seriously compromised by its failure to adequately fit the data. The studies used by the USEPA also likely underestimate TCDD body burdens and may be confounded by smoking and other occupational exposures. Furthermore, the use of a linear dose-response model by the USEPA is scientifically unjustified since the underlying model of TCDD as a human carcinogen is based primarily on its supposed receptor-mediated, non-genotoxic (or promotional) mode of action. There are few examples of an agent being suspected as a human carcinogen for decades and then eventually moving into the category of "known" human carcinogens. In contrast, there are hundreds of compounds that remain for decades on lists of "suspected" human carcinogens despite the lack of confirming evidence. The long-term accumulation of negative, weak, and inconsistent findings suggests that TCDD eventually will be recognized as not carcinogenic for humans.

Evidence from environmental burden-of-disease studies can provide valuable input in the decision-making process in environmental health, facilitating priority setting and cost effectiveness evaluation. This paper discusses important aspects of environmental burden-of-disease estimates in the light of) published examples. To produce reliable and comparable burden-of-disease estimates for environmental and occupational risk factors, harmonized methods are needed. Such methods should address the feasibility of data collection at national, regional, and global levels, the reliability of estimates, the uncertainty around estimates, and scenario tools to investigate the health gains of options for preventive action in different domains of policy. Any such method will require a framework (i.e., causal inference model) able to take into account the contributions of distal and proximal causes, and the possible interactions between risk factors.

This research was conducted to examine the effect of model choice on the epidemiologic interpretation of occupational cohort data. Three multiplicative models commonly employed in the analysis of occupational cohort studies--proportional hazards. Poisson, and logistic regression--were used to analyze data from an historical cohort study of workers exposed to formaldehyde. Samples were taken from this dataset to create a number of predetermined scenarios for comparing the models, varying study size, outcome frequency, strength of risk factors, and follow-up length. The Poisson and proportional hazards models yielded nearly identical relative risk estimates and confidence intervals in all situations except when confounding by age could not be closely controlled in the Poisson analysis. Logistic regression findings were more variable, with risk estimates differing most from the proportional hazards results when there was a common outcome or strong relative risk. The logistic model also provided less precise estimates than the other two. Thus, although logistic was the easiest model to implement, it should be used only in occupational cohort studies when the outcome is rare (5% or less), and the relative risk is less than approximately 2. Even then, the proportional hazards and Poisson models are better choices. Selecting between these two can be based on convenience in most circumstances.

Objective: To carry out a community-based research approach to determine the most effective educational interventions to reduce smoking among African-American smokers. The intervention included preparation of the community, planning and developing a model of change, and developing a community-based intervention. The study population consisted of 2,544 randomly selected adult African-American smokers residing in four sites in the northeastern and southeastern parts of the United States. The research design provided a comparison of active intervention sites with passive control sites as well as low income and moderate income areas., Major Outcome Measures: Point prevalence of non-smoking at the time of interview; Period prevalence of non-smoking at the time of interview; Period prevalence of quit attempts in the prior six months; Number of smoke-free days in the prior six months; Number of cigarettes smoked daily at the time of interview., Results: Based upon a survey eighteen months after baseline data was collected, all four measures of cigarette smoking behavior showed a strong statistically significant reduction of personal smoking behavior among those receiving active interventions versus the passive group. On the basis of process variable analysis, direct contact with the project staff in the prior six months was significantly higher in the active intervention areas. There was only a small non-significant increase in personal smoking behavior in moderate income groups as opposed to low income groups., Conclusion: An analysis of process variables strongly suggests that, within this African-American Community, "hands on" or "face to face" approaches along with mass media, mailings, and other less personal approaches were more effective in reducing personal smoking behavior than media, mailings, and other impersonal approaches alone addressed to large audiences.

There is a great amount of ongoing discussion about the need to develop new ways to assess and monitor a population's disease susceptibility to environmental factors. The ultimate goal in developing these tools, called environmental health indicators, is to increase the public health community's capacity for implementing interventions to prevent disease. Much of the discussion focuses on the requirement that the indicators be relatively easy and quick to apply. However, in the rush to find useful existing indicators, or to develop new ones, there is the danger that certain other important attributes of the indicator may be overlooked. These include: (a) whether the indicator truly represents an underlying causal relationship between an environmental exposure and a health consequence; and (b) whether the proposed indicator is a reasonably valid estimate of the underlying causal factor. This article provides a framework for relating environmental health indicators to the methods of epidemiology including some guidance for selecting and evaluating the appropriateness of proposed environmental health indicators. Examples are given which demonstrate how environmental health indicators can lead to a biased interpretation of underlying associations between environmental factors and the potential for disease when they are improperly conceived. These problems can be avoided by employing routine epidemiological concepts and methods as indicators are developed and evaluated.

A retrospective cohort study was conducted to examine the risk of mortality, cancer, and other adverse health outcomes, at the United States' largest chromate chemicals manufacturing facility in Castle Hayne, North Carolina. This facility, built in 1971, was designed to reduce the high levels of chromium exposure found at most older facilities. Exposure assessment was based on analysis of more than 5,000 personal breathing zone samples collected over a 15-year period. A questionnaire was used to collect relevant occupational, medical, smoking, and other information from current and former employees. Analysis of the cohort's mortality experience found no substantial departures from that expected based on external comparisons, although evidence of a healthy worker effect was observed. Internal cohort analyses were limited by relatively small numbers; however, a subgroup of employees who transferred from older facilities was found to have higher risks of mortality (odds ratio = 1.27 for each 3 years of previous exposure; 90% confidence interval (CI) = 1.07-1.51) and cancer (odds ratio = 1.22 for each 3 years of previous exposure; 90% CI = 1.03-1.45). While this subgroup represented only 11% of the individuals in this study, they accounted for 46% (6/13) of all observed cancers (excluding skin cancers) and 60% (3/5) of lung cancers. There was no increased risk of mortality or cancer among employees who worked only at the newer facility. As an etiologic research study, the results are limited by the relatively small number of subjects and short follow-up; nevertheless, the findings can be used to design and implement a prospective surveillance system for monitoring the health of chromate production workers.

Background and Objectives: We postulated that epidural sufentanil alone would provide adequate analgesia for labor and delivery. We also considered the possibility that a combination of epidural sufentanil and bupivacaine would demonstrate superior analgesia and fewer side effects when compared with either agent alone., Methods: Using a randomized, double-blind design, parturients were prospectively assigned to receive intermittent 10-ml doses of 3 micrograms/ml sufentanil in saline (Group S), 1.5 micrograms/ml sufentanil in 0.125% bupivacaine (Group SB), or 0.25% bupivacaine (Group B). Lumbar epidural catheters were placed during the first stage of labor, and a test dose (3 ml 2% lidocaine with 15 micrograms epinephrine) was given, followed by coded study solution. Subsequent doses of study solution were given at the patient's request. Those parturients who remained uncomfortable after 30 minutes were given 10 ml 2% lidocaine and were designated efficacy failures. Patients were evaluated for quality and duration of analgesia for each dose. Neonates were assessed using Apgar scores and the neonatal behavioral assessment scale. Maternal and umbilical venous sufentanil concentrations were measured at the time of delivery., Results: All patients received satisfactory analgesia of similar duration after the first epidural dose. After subsequent doses, women in Group S experienced more efficacy failures (Groups S, SB, and B, respectively, 12 of 26, 5 of 22, and 1 of 25; p less than 0.005) and received briefer, less intense analgesia compared to the other groups. Instrumental delivery was performed more frequently for women in Group B (Groups S, SB, and B, respectively, 0 of 14, 2 of 17, and 7 of 24; p = 0.04). No serious maternal side effects occurred. Apgar and neurobehavioral scores were comparable for all groups, with the exception that Group B infants had higher irritability scores at 1 hour of age (p = 0.003). Neither maternal nor umbilical venous sufentanil concentrations bore a consistent relationship to clinical outcomes., Conclusions: Epidural sufentanil alone does not reliably provide satisfactory analgesia for labor and delivery. Addition of small amounts of local anesthetic to bolus doses of sufentanil enhances and prolongs the analgesic effect.

The case-control study is quite popular as a study design for exploring associations between risk factors and disease in pediatric epidemiology. Since data concerning exposures to the child are often collected through interviews with parents or other surrogates, researchers should be aware of the opportunities for bias due to inaccurate or incomplete recall. Methods which exist for the control of this problem are presented. These include: the selection of control groups with childhood conditions of similar etiologic uncertainty as the disease being studied; collecting exposure data from both parents; collection of data from children where possible; diligent interviewer training; reviewing clinical records; and use of validity scales. Strengths and weaknesses of these strategies are discussed.

The risk of adverse reproductive outcomes was examined among semiconductor manufacturers. Personal interviews were conducted with manufacturing workers, spouses of male manufacturers, and an internal comparison group of non-manufacturing workers. Elevated spontaneous abortion ratios were observed for females working in the "diffusion" (38.9%; relative risk = 2.18, 95% confidence interval estimate = 1.1, 3.6) and photolithographic process (31.1%; relative risk = 1.75, 95% confidence interval estimate = 0.8, 3.3). Analysis of potential confounding did not substantially alter the findings. The potential for recall bias was also assessed; although the confidence interval for the comparison of diffusion and non-manufacturing workers no longer excluded 1.0, an excess risk was still reflected. No substantive differences in other reproductive outcomes were identified. Various general health symptoms were examined and reported more frequently among manufacturers than non-exposed. These results should be viewed as tentative until studies with larger numbers and more detailed exposure data are carried out.

This paper presents results of the first study explicitly designed to compare three methods for predicting hospital mortality of ICU patients: the Acute Physiology Score (APS), the Simplified Acute Physiology Score (SAPS), and the Mortality Prediction Model (MPM). With respect to sensitivity, specificity, and total correct classification rates, these methods performed comparably on a cohort of 1,997 consecutive ICU admissions. In these patients from a single hospital, the APS overestimated and the SAPS underestimated the probability of hospital mortality. The MPM probabilities most closely matched the observed outcomes. Each method holds considerable promise for assessing the severity of illness of critically ill patients. The MPM should be particularly useful for comparing ICU performance, since it is independent of ICU treatment and can be calculated at the time a patient is admitted.

The relationship between use of oral contraceptives and fibrocystic breast disease was examined in a hospital-based case-control study undertaken in New Haven, Connecticut, from 1977 to 1979. Particular emphasis was placed on the extent of epithelial atypia and other histopathologic characteristics found in the biopsy specimens from the cases. Women who had ever used oral contraceptives were at a somewhat decreased risk for fibrocystic disease as a whole. Cases with high atypia and controls had similar patterns of oral contraceptive use, whereas cases with low and intermediate atypia had less oral contraceptive use than controls. Cases with intermediate atypia reported the lowest oral contraceptive use. Subjects with biopsy specimens exhibiting gross cysts, microscopic cysts, or papillomatosis were about 50% less likely to have used oral contraceptives than controls.

Proportionate mortality among workers exposed to formaldehyde was analyzed among employees of a large chemical plant in Western Massachusetts. Twenty-four such decedents, all males, were identified through union records, reports of former co-workers, and a systematic review of obituaries in local newspaper. Work histories were obtained from seniority lists. Race-age-sex-adjusted proportionate mortality ratios ( PMRs ) were significantly elevated for cancer of the colon based on United States, county, and county cancer mortality proportions (PMR = 702, 424, 333, p less than or equal to .05), as were PMRs for the category buccal and pharyngeal cancer (PMR = 870, 952, 833, p less than .05). This study provides evidence of formaldehyde's carcinogenicity. These findings are at variance with a previous report of the mortality experience of workers at the same plant from an earlier period.

In a hospital-based case-control study conducted in New Haven, Connecticut, women experiencing estrogen replacement therapy were found to be at twice the risk of nonusers for histologically confirmed fibrocystic breast disease (odds ratio = 2; 95 percent confidence limits = 1-3.9) if their menopause was natural. No excess risk was found for women experiencing a surgical menopause. The highest risk for fibrocystic disease was observed for women with more than three years of estrogen replacement therapy. When therapy occurred was not significantly related to the risk of disease once duration of use was controlled for. These results suggest an etiologic role of estrogen replacement therapy in the development or promotion of fibrocystic breast disease.

Injuries to the upper extremity, as reported in home interviews, physician office records, and hospital records, are a problem of great magnitude. Upper extremity injuries not only are responsible for a great deal of disability and for a large number of visits for medical care, but also, because they often affect people of working age, have a great impact on society because of loss of productivity. However, regardless of the age at which they occur, these injuries can have an impact on the quality of life of the injured, both in the short term and in the long.

Data at ICU admission and after 24 h in the ICU were collected on 755 patients, to derive multiple logistic regression models for predicting hospital mortality. The derived models contained relatively few and easily obtained variables. The weight associated with each variable was determined objectively. There were seven admission variables, none of which were treatment dependent, and seven 24-h variables reflecting treatments and patients' conditions in the ICU. Predicted outcomes using these two models were closely correlated with actual outcome. Theoretically, a predictive model would be useful to physicians for triage decisions as well as determining aggressiveness of care through discussions with families, determining utilization of ICU facilities, and objectively comparing different ICUs. This research represents an initial attempt to develop models that are not based on subjectively determined weights.

The occurrence of diabetes, hypertension, and diaphragmatic hernia was investigated in an institutionalized population of long-term epileptics. Review of medical records determined the prevalence ratio of diabetes to be about 1.6% and the prevalence of hypertension to be about 2.3%. Both of these estimates are significantly lower than the rates in the general US population. The prevalence of diaphragmatic hernia among females (4.8%) was found to be significantly higher than the general population rate, but the corresponding ratio among males (3.6%) was not. Associations with major drugs used were subsequently investigated using a case-control methodology. Implications for etiologic research are discussed.

Most cases of beta-lactam-associated coagulopathy occur in patients with other risk factors. This study analyzed temporally related clinical bleeding events in 1493 patients who received one antibiotic for at least three days. Univariate and multivariate analyses controlled for condition variables (nutritional status, renal, hepatic, or hematologic dysfunction, intensive care unit stay) and treatment variables (use of antiplatelet agents, anticoagulants, vitamin K, antitumor chemotherapy or antiulcer therapy, steroids) that could have been associated with bleeding independently. Rates of bleeding ranged from 0% (chloramphenicol sodium succinate, vancomycin hydrochloride, erythromycin lactobionate) to 8.2% (cefoxitin) to 22.2% (moxalactam disodium). Multiple logistic regression analyses revealed that only moxalactam (odds ratio, 9.9) and cefoxitin (odds ratio, 2.1) exhibited significantly higher likelihoods of bleeding than other agents. This study statistically confirms increased risk of bleeding with moxalactam, heretofore reported only anecdotally. Cefoxitin may carry risks greater than previously believed.

This study was initiated in order to estimate and compare the occurrence of nutritional anemia in three groups of adolescents and young adults. The first group comprised 159 individuals aged 14-21, who had been previously screened for thalassemia in three Connecticut cities. The second group was made up of 163 Derby High School students, aged 14-18, who had also been previously screened for thalassemia. The third group consisted of 118 Yale undergraduate students, aged 16-21, who were monitored for nutritional anemia while undergoing routine physical examinations at the Yale University Health Service. The prevalence of nutritional anemia varied from 0.0 percent to 5.5 percent among the three female groups, and from 4.4 percent to 17.9 percent among the three male groups. Only the Yale undergraduate male group was found to be from this condition. The Yale undergraduate females were discovered to have the highest prevalence. Mean hemoglobin levels of the male and female groups we also compared.

Sixty-four children aged 1-4 years were evaluated for the extent to which they ingest soil. The study followed the soil tracer methodology of S. Binder, D. Sokal, and D. Maughan (1986, Arch. Environ. Health, 41, 341-345). However, the present study included a number of modifications from the Binder et al. study. The principal new features were (1) increasing the tracer elements from three to eight; (2) using a mass-balance approach so that the contribution of food and medicine ingestion would be considered; (3) extending the period of observation from 3 days to 8 days; and (4) validating the methodology by having adult volunteers ingest known amounts of soil in a mass-balance validation study. The principal findings reveal the following. (1) The adult study confirmed the validity of the tracer methodology to estimate soil ingestion. (2) Of the eight tracers employed in the adult study, only Al, Si, and Y provided sufficient recovery data that was directly acceptably stable and reliable. (3) If food ingestion determinations were taken into consideration, the median estimates of soil ingestion from the eight tracers ranged from a low of 9 mg/day (Y) to a high of 96 mg/day (V); the median values of Al, Si, and Y, the three most reliable tracers, ranged from 9 mg/day to 40 mg/day. (4) One child had soil ingestion values ranging from 5 to 8 g/day, depending on the tracer. (5) If food ingestion had not been considered, the estimates of soil ingestion would have increased about two- to sixfold, depending on the tracer with Ti and Y being most affected by food intake. (6) Since soil and dust samples did not significantly differ in their levels of tracer elements, no reliable differentiation between the contribution of ingestion of dust and soil could be made. (7) These findings are generally consistent with the previously reported findings of Binder et al. (1986) and P. Clausing, B. Brunekreff, and J.H. van Wijnen (1987, Int. Arch. Occup. Med., 59, 73) if these latter studies are corrected for ingestion of tracers in food and medicine. The findings also account for the apparent discrepancy between the estimates from Al and Si and estimates based on Ti in previous studies. Thus the elevated estimates of soil ingestion by Ti were substantially reduced when food ingestion is considered.

Increasing reliance is being placed on the use of quantitative epidemiological methods in the conduct and evaluation of pediatric research. The basic design features of two common types of observational studies, the case-control study and the cohort study, are reviewed. Advantages and disadvantages of these two study designs are discussed with emphasis on aspects such as the selection of comparison groups, avoiding selection and recall bias, gathering exposure information, controlling for potentially confounding factors, and methods of analysis. Appreciation of the salient features of these study design approaches should aid the clinician/researcher in the conduct of research endeavors as well as in critically reviewing the medical literature.