Issues in the reporting of epidemiological studies: a survey of recent practice.

OBJECTIVES: To review current practice in the analysis and reporting of epidemiological research and to identify limitations. DESIGN: Examination of articles published in January 2001 that investigated associations between risk factors/exposure variables and disease events/measures in individuals. SETTING: Eligible English language journals including all major epidemiological journals, all major general medical journals, and the two leading journals in cardiovascular disease and cancer. MAIN OUTCOME MEASURE: Each article was evaluated with a standard proforma. RESULTS: We found 73 articles in observational epidemiology; most were either cohort or case-control studies. Most studies looked at cancer and cardiovascular disease, even after we excluded specialty journals. Quantitative exposure variables predominated, which were mostly analysed as ordered categories but with little consistency or explanation regarding choice of categories. Sample selection, participant refusal, and data quality received insufficient attention in many articles. Statistical analyses commonly used odds ratios (38 articles) and hazard/rate ratios (23), with some inconsistent use of terminology. Confidence intervals were reported in most studies (68), though use of P values was less common (38). Few articles explained their choice of confounding variables; many performed subgroup analyses claiming an effect modifier, though interaction tests were rare. Several investigated multiple associations between exposure and outcome, increasing the likelihood of false positive claims. There was evidence of publication bias. CONCLUSIONS: This survey raises concerns regarding inadequacies in the analysis and reporting of epidemiological publications in mainstream journals

Large Prospective Study of Ovarian Cancer Screening in High-Risk Women: CA125 Cut-Point Defined by Menopausal Status

Previous screening trials for early detection of ovarian cancer in postmenopausal women have used the standard CA125 cut-point of 35 U/mL, the 98th percentile in this population yielding a 2% false positive rate, while the same cut-point in trials of premenopausal women results in substantially higher false positive rates. We investigated demographic and clinical factors predicting CA125 distributions, including 98th percentiles, in a large population of high-risk women participating in two ovarian cancer screening studies with common eligibility criteria and screening protocols

Unmet need among disabled elders: A problem in access to community long term care?

To more completely understand unmet need as an indicator of demand for long-term care, longitudinal data on a representative sample of disabled elders were used to track the extent, type, and predictors of unmet need(s) over a 4-year period. Unmet IADL needs were more common than unmet PADL needs with only 1-2% reporting both types. Unmet needs appear to be temporary rather than persistent and are predicted by lack of an engaged (not necessarily unavailable) caregiving system. The data suggest that the rate of unmet personal care need rather than the rate of any unmet need represents a more accurate estimate of the number of elders for whom community long-term care services are critical to decrease risk of institutionalization.long-term care unmet need disabled elders

Subgroup analysis, covariate adjustment and baseline comparisons in clinical trial reporting: current practice and problems.

Clinical trial investigators often record a great deal of baseline data on each patient at randomization. When reporting the trial's findings such baseline data can be used for (i) subgroup analyses which explore whether there is evidence that the treatment difference depends on certain patient characteristics, (ii) covariate-adjusted analyses which aim to refine the analysis of the overall treatment difference by taking account of the fact that some baseline characteristics are related to outcome and may be unbalanced between treatment groups, and (iii) baseline comparisons which compare the baseline characteristics of patients in each treatment group for any possible (unlucky) differences. This paper examines how these issues are currently tackled in the medical journals, based on a recent survey of 50 trial reports in four major journals. The statistical ramifications are explored, major problems are highlighted and recommendations for future practice are proposed. Key issues include: the overuse and overinterpretation of subgroup analyses; the underuse of appropriate statistical tests for interaction; inconsistencies in the use of covariate-adjustment; the lack of clear guidelines on covariate selection; the overuse of baseline comparisons in some studies; the misuses of significance tests for baseline comparability, and the need for trials to have a predefined statistical analysis plan for all these uses of baseline data

Carbon Nanotube Arrays for Enhanced Thermal Interfaces to Thermoelectric Modules

Thermoelectric materials exploit the Seebeck effect in which an electric potential is generated from a supplied temperature gradient. High thermal conductance through the interfaces between the thermoelectric module and its heat source and sink is crucial for generating maximum power. Primarily due to increased surface contact area and inherently low diffusive thermal resistance, carbon nanotube arrays can provide low thermal interface resistance. Vertically aligned carbon nanotube arrays are synthesized on one or both sides of copper foil by microwave plasma chemical vapor deposition. Growth of similar structures on graphitic foil resulted in carbon nanofiber arrays. The products become insertable thermal interface materials. The thermal interface materials are evaluated by measuring the efficiency of a standard bismuth-telluride thermoelectric module with the thermal interface materials applied. Experiments indicate that a copper foil coated on both sides with carbon nanotubes increases thermoelectric power generation by 60% relative to the absence of thermal interface materials and by 25% relative to a bare copper foil. Photoacoustic results indicate that the thermal interface resistance decreases due to the presence of a carbon nanotube, reaching a minimum of 17 mm(2) K/W for a double-sided carbon nanotube film on copper foil. However, carbon nanofiber arrays on graphitic foil showed no improvement in thermoelectric performance or decrease in thermal interface resistance

STATISTICS IN MEDICINE

Subgroup analysis, covariate adjustment and baseline comparisons in clinical trial reporting: current practice and problem

Visiting medical student elective and clerkship programs: a survey of US and Puerto Rico allopathic medical schools

Abstract Background No published reports of studies have provided aggregate data on visiting medical student (VMS) programs at allopathic medical schools. Methods During 2006, a paper survey was mailed to all 129 allopathic medical schools in the United States and Puerto Rico using a list obtained from the Association of American Medical Colleges. Contents of the survey items were based on existing literature and expert opinion and addressed various topics related to VMS programs, including organizational aspects, program objectives, and practical issues. Responses to the survey items were yes-or-no, multiple-choice, fill-in-the-blank, and free-text responses. Data related to the survey responses were summarized using descriptive statistics. Results Representatives of 76 schools (59%) responded to the survey. Of these, 73 (96%) reported their schools had VMS programs. The most common reason for having a VMS program was "recruitment for residency programs" (90%). "Desire to do a residency at our institution" was ranked as the leading reason visiting medical students choose to do electives or clerkships. In descending order, the most popular rotations were in internal medicine, orthopedic surgery, emergency medicine, and pediatrics. All VMS programs allowed fourth-year medical students, and approximately half (58%) allowed international medical students. The most common eligibility requirements were documentation of immunizations (92%), previous clinical experience (85%), and successful completion of United States Medical Licensing Examination Step 1 (51%). Of the programs that required clinical experience, 82% required 33 weeks or more. Most institutions (96%) gave priority for electives and clerkships to their own students over visiting students, and a majority (78%) reported that visiting students were evaluated no differently than their own students. During academic year 2006-2007, the number of new resident physicians who were former visiting medical students ranged widely among the responding institutions (range, 0-76). Conclusions Medical schools' leading reason for having VMS programs is recruitment into residency programs and the most commonly cited reason students participate in these programs is to secure residency positions. However, further research is needed regarding factors that determine the effectiveness of VMS programs in residency program recruitment and the development of more universal standards for VMS eligibility requirements and assessment.</p