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S B Thacker

Publications and source records attributed to S B Thacker.

At least 37 records · Page 2Linked to original sources
PubMed1997

Comparison of effect estimates from a meta-analysis of summary data from published studies and from a meta-analysis using individual patient data for ovarian cancer studies.

To determine the relative merits of two quantitative methods used to estimate the summary effects of observational studies, the authors compared two methods of meta-analysis. Each quantified the relation between oral contraceptive use and the risk for ovarian cancer. One analysis consisted of a meta-analysis using summary data from 11 published studies from the literature (MAL) in which the study was the unit of analysis, and the second consisted of a meta-analysis using individual patient data (MAP) in which the patient was the unit of analysis. The authors found excellent quantitative agreement between the summary effect estimates from the MAL and the MAP. The MAP permits analysis 1) among outcomes, exposures, and confounders not investigated in the original studies, 2) when the original effect measures differ among studies and cannot be converted to a common measure (e.g., slopes vs. correlation coefficients), and 3) when there is a paucity of studies. The MAL permits analysis 1) when resources are limited, 2) when time is limited, and 3) when original study data are not available or are available only from a biased sample of studies. In public health epidemiology, data from original studies are often accessible only to limited numbers of research groups and for only a few types of studies that have high public health priority. Consequently, few opportunities for pooled analysis exist. However, from a policy view, MAL will provide answers to many questions and will help in identifying questions for future investigation.

Bias↗
PubMed1997

National public health surveillance in China: implications for public health in China and the United States.

STUDY OBJECTIVE: Throughout the world, political developments have brought new demands to communities to prevent and intervene in the incidence of infectious and noninfectious conditions. Historically, these developments have required new and more effective public health surveillance activities. This report describes public health surveillance practice in the People's Republic of China, making comparisons with selected aspects of surveillance in the United States with respect to collection, analysis, dissemination, and use of data. MAIN RESULTS: In both the People's Republic of China and the United States, political change has affected health, and multiple surveillance system are used in public health practice. Surveillance of acute infectious diseases based on the reporting of legally notifiable diseases and the use of vital records for surveillance have the longest established history in both countries. In both countries, data from the surveillance systems have been used to affect public health policy. CONCLUSIONS: In comparing surveillance practices in these countries, we find similarities in conditions reported and in the dissemination of the data. At the same time, legal, social, cultural, and economic differences between the nations have affected the practice of surveillance in analysis and evaluation. We make explicit recommendations for improvement and evaluation of systems in both countries, including sentinel surveillance system and data quality measures in China and computer networking and data analysis in the United States.

Centers for Disease Control and Prevention, U.S.↗
PubMed1996

Metaanalysis for the obstetrician-gynecologist.

To provide guidance to obstetricians and gynecologists for using findings from metaanalyses in clinical practice, we describe the principles and methods of metaanalysis, including its strengths and weaknesses. Then we illustrate these principles by reviewing four metaanalyses published recently in the American Journal of Obstetrics and Gynecology by using a systematic approach to evaluation based on 15 questions. In these published metaanalyses most of the questions are addressed, but we noted an absence of attention to coding aspects in all studies. The usefulness of metaanalysis largely depends on the quality of the studies that are synthesized, the conduct of the metaanalysis, and the reporting of the methods and results. Proper use of metaanalyses requires an understanding of the strengths and weaknesses of the method and attention to the manner of reporting. The principles of metaanalysis are not complex, and the potential benefits can be enormous for patient care.

Evaluation Studies as Topic↗
PubMed1996

The future of national public health surveillance in the United States.

Public health surveillance systems should have the capacity to collect and analyze data, disseminate data to public health programs, and regularly evaluate the effectiveness of the use of disseminated data. Unfortunately, in the United States, systems of public health surveillance are fragmented and do not adequately address either current or new potential challenges to public health. This commentary addresses components of any effort toward a national public health surveillance system and highlights examples of these components in state and national surveillance developments.

Confidentiality↗
PubMed1996

Surveillance in environmental public health: issues, systems, and sources.

This article describes environmental public health surveillance and proposes a framework to enhance its practice in the United States. Special issues for surveillance in environmental public health are examined, and examples of existing systems useful for environmental public health practice are provided. Current and projected surveillance needs, as well as potential sources of data, are examined. The proposed framework for conducting environmental public health surveillance involves data from three points in the process by which an agent in the environment produces an adverse outcome in a host: hazards, exposures, and outcomes. Environmental health practitioners should build on efforts in other fields (e.g., infectious diseases and occupational health) to establish priorities in the surveillance of health conditions associated with exposure to environmental toxicants. For specific surveillance programs, existing data systems, as well as data gaps, should be identified. Coordinated surveillance systems can facilitate public health efforts to prevent and control disease, injury, and disability related to the interaction between people and their environment.

Environmental Exposure↗
PubMed1995

Efficacy and safety of intrapartum electronic fetal monitoring: an update.

OBJECTIVE: To compare the efficacy and safety of routine electronic fetal monitoring (EFM) of labor with intermittent auscultation, using the results of published randomized controlled trials (RCTs). DATA SOURCES: We identified RCTs by searching the MED-LINE data base for the period 1966-1994, contacting experts, and reviewing published references. METHODS OF STUDY SELECTION: Our search identified 12 published RCTs addressing the efficacy and safety of EFM; no unpublished studies were found. The studies included 58,855 pregnant women and their 59,324 infants in both high- and low-risk pregnancies from ten clinical centers in the United States, Europe, Australia, and Africa. DATA EXTRACTION AND SYNTHESIS: Data were abstracted, and their accuracy was confirmed independently. A single reviewer assessed study quality based on criteria developed by others for RCTs. Data reported from similar studies were used to calculate a combined risk estimate for each of nine outcomes. Overall, a statistically significant decrease was associated with routine EFM for a 1-minute Apgar score less than 4 (relative risk [RR] 0.82, 95% confidence interval [CI] 0.65-0.98) and neonatal seizures (RR 0.5, 95% CI 0.30-0.82). The protective effect of EFM for a 1-minute Apgar score less than 4 was apparent only in the non-United States studies, and the protective effect for neonatal seizures was evident only in studies with high-quality scores. No significant differences were observed in 1-minute Apgar scores less than 7, rate of admissions to neonatal intensive care units, and perinatal death. An increase associated with the use of EFM was observed in the rate of cesarean delivery (RR 1.33, 95% CI 1.08-1.59) and total operative delivery (RR 1.23, 95% CI 1.15-1.31). Risk of cesarean delivery was greatest in low-risk pregnancies. CONCLUSION: The only clinically significant benefit from the use of routine EFM was in the reduction of neonatal seizures. Because of the increase in cesarean and operative vaginal deliveries, the long-term benefit of this reduction must be evaluated in the decision reached jointly by the pregnant woman and her clinician to use EFM or intermittent auscultation during labor.

Female↗
PubMed1994

Future directions for comprehensive public health surveillance and health information systems in the United States.

The authors describe a comprehensive system for public health surveillance for the United States based on a network of data systems ranging from population surveys and physician-based records to electronically linked laboratory and administrative data. They also discuss traditional uses of surveillance data, legal and ethical issues associated with using data from any surveillance system (particularly the tension between individual privacy and the public right to a healthful environment), and factors impeding the development of a comprehensive system. Just as provisional data on notifiable diseases are critical in protecting communities from disease, data from other information systems should be applied to prevention practice with the same urgency. The major barriers to a successful comprehensive, nationwide, integrated public health surveillance and information system are a lack of appreciation for the value of high-quality provisional surveillance data and a weak societal commitment to public health.

Confidentiality↗
PubMed1994

Infectious diseases in competitive sports.

OBJECTIVE: Participation in competitive sports is popular and widely encouraged throughout the United States. Reports of infectious disease outbreaks among competitive athletes and recent publicity regarding infectious disease concerns in sports underscore the need to better characterize the occurrence of these problems. DATA SOURCES: To identify reports of infectious diseases in sports, we performed a comprehensive search of the medical literature (MEDLINE) and newspaper databases in two on-line services (NEXIS and DIALOG PAPERS). STUDY SELECTION: Articles selected from the literature review included those describing cases or outbreaks of disease in which exposure to an infectious agent was likely to have occurred during training for competitive sports or during actual competition. Articles from the newspaper review included reports of outbreaks, exposures, or preventive measures that directly or indirectly involved teams or spectators. DATA SYNTHESIS: The literature review identified 38 reports of infectious disease outbreaks or other instances of transmission through person-to-person (24 reports), common-source (nine reports), or airborne (five reports) routes; the newspaper search identified 28 reports. Infectious agents included predominantly viruses but also a variety of fungi and gram-positive and gram-negative bacteria. CONCLUSIONS: Our findings indicate that strategies to prevent transmission of infectious diseases in sports must recognize risks at three levels: the individual athlete, the team, and spectators or others who may become exposed to infectious diseases as a result of sports-related activities. Team physicians and others who are responsible for the health of athletes should be especially familiar with the features of infectious diseases that occur in sports and measures for the prevention of these problems.

Communicable Disease Control↗
PubMed1994

Breast cancer risk and duration of estrogen use: the role of study design in meta-analysis.

Recent meta-analyses of studies of the risk of breast cancer associated with hormone replacement therapy agree that little risk is associated with ever-use or short-term use of estrogen replacement. These analyses disagree, however, about the effect of long-duration estrogen use. To understand differences in the findings among the meta-analyses of the effect of long-term use, we investigated the source of heterogeneity among the included studies. We analyzed subgroups by source of controls (community vs hospital), study design (case-control vs follow-up), and types of estrogen. We also examined the effect of modeling assumptions: that before women began estrogen use, those who chose to use estrogen replacement (1) were, or (2) were not, at substantially different risk from those who chose not to use estrogen. We found a small increase in risk in all subgroups of studies except those that used hospital controls. From a homogeneous group of case-control studies using community controls that analyzed the effect of conjugated equine estrogens, we estimated that the risk of breast cancer after 10 years of estrogen use increased by at least 15% and up to 29%.

Breast Neoplasms↗
PubMed1994

Relative risks and benefits of long-term estrogen replacement therapy: a decision analysis.

OBJECTIVE: To evaluate the relative risks and benefits of exogenous estrogen use among women entering the climacteric and to consider estrogen use for relief of symptoms or prevention of disease. METHODS: Decision analysis was used to assess the value of estrogen replacement therapy in a hypothetical cohort of 10,000 women assumed to be age 50 years; health outcomes were extrapolated to age 75. Risk ratios for mortality and morbidity of health outcomes associated with the use of estrogen replacement therapy were based on longitudinal studies reported in the literature. RESULTS: Estrogen use for 25 years would decrease fatal coronary heart disease events by 48% (567 cases), decrease deaths from hip fracture by 49% (75), increase deaths from breast cancer by 21% (39), and increase deaths from endometrial cancer by 207% (29 excess deaths). On balance, 25 years of estrogen replacement therapy in a cohort of 10,000 women would prevent 574 deaths. Further, women using estrogens for 25 years would gain 3951 quality-adjusted life years compared with women not using estrogens. Sensitivity analysis suggests that the benefits of estrogen replacement therapy outweight the risks under most assumptions. CONCLUSION: In a hypothetical, population-based analysis, the health benefits of postmenopausal estrogen replacement exceed the health risks incurred. Nevertheless, clinicians must still evaluate each individual's risks and needs.

Aged↗
PubMed1993

A Bayesian approach to the detection of aberrations in public health surveillance data.

The accurate and timely detection of unusual patterns in data from public health surveillance systems presents an important challenge to health workers interested in early identification of epidemics or clues to important risk factors. We apply the Kalman filter, a Bayesian method, to public health surveillance data collected in the United States to illustrate a methodology used to detect sudden, sustained changes in reported disease occurrence, changes in the rate of change of health event occurrence, as well as unusual reports or outliers. The method allows use of information external to reported data in forecasting expected numbers, information such as expert judgment, changes in case definition or reporting practices, or changes in the health event process. Results show good agreement with epidemiologically established patterns beginning early in the data series and demonstrated usefulness on a relatively short series. Because the method is unfamiliar to most practicing epidemiologists in public health, it should be compared with other techniques and made more "user-friendly" before general application.

Acquired Immunodeficiency Syndrome↗