Predicting risk among non-respondents in prospective studies

Potential non-response bias was investigated in a follow-up study of 2,011 chronically disabled patients. 82.5% and 73.3% of the study subjects responded to self-administered mail questionnaires respectively at 6-month and 1-year follow-up. Information on employment status, the outcome of interest, of approximately 90% of the non-respondents was obtained from indirect sources. Employment rate was lower among the non-respondents than the respondents. Non-response was associated with age, social class, previous employment record, and the type of disability; but none of these characteristics were associated with the outcome. Out of the five known independent risk factors for unemployment, only one (incompletion of rehabilitation course) was associated with non-response. The employment rate among the respondents was also assessed according to the delay in response, that is the number of reminders sent to achieve response. The outcome among- the late respondents was similar to that among the nonrespondents. These data suggest that (a) risk estimates may be biased even when the response rate is greater than 80%, (b) the prevalence of risk factors among non-respondents may not indicate the presence or the degree of non-response bias, but (c) reliable estimates can be obtained from extrapolations of the rates among the respondents according to the delay in response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42663/1/10654_2004_Article_BF00152716.pd

The Implementation of an Experimental Research Design in the Evaluation of an Intervention to Prevent AIDS among IV Drug Users

A demonstration project, currently in progress in Miami, is using an experimental research design to evaluate an AIDS intervention program among IV drug users and the sexual partners of IV drug users. At the time of the initial assessment, which includes a blood test to determine HIV serostatus and an extensive interview, study participants are randomized into either a standard or an enhanced intervention protocol. The enhanced intervention group receives more intensive counseling including individual as well as group sessions. Follow-up assessments of both groups are made at six-month intervals. The before/after comparisons will assess whether frequency of risk behaviors have changed and whether observed changes are greater in the enhanced group than the standard group. Randomization to two alternative intervention groups allows for the control of many potential biases that plague other types of before/after research designs

Which book? A comparative review of 25 introductory epidemiology textbooks.

We are witnessing an epidemic of epidemiology. One outcome is a greater demand for books to meet the needs of an increasingly diverse student body. A widening range of professionals and researchers are discovering the power and fascination of the subject, and their heterogeneity of specialist knowledge and interest poses special challenge. Revisions of classics and many new texts mean difficult choices for teachers and students. The rise of epidemiology will spur new writings so we can anticipate even more. This review is primarily to help students and teachers to find the first textbook for the keen postgraduate or undergraduate. Practitioners may welcome this as a way of tracking down the book which covers epidemiology in the style they prefer. Aspiring text book writers might see gaps for future work. I have concentrated on books published since 1980 and in choosing which books to review I was guided by these questions: Might students chose this book as their first textbook? Might teachers recommend this book for general, introductory reading? Is the book attractive to students and teachers on the basis of reputation? Is it already in use as a general text? If yes, my tendency was to review it. Specialist, advanced, and reference works were excluded, especially if the author(s) did not consider the book as introductory. Some books consisting of exercises and meant for self study have been included if they tried to cover the theory and principles too. I hope to have included the main contenders for the first textbook role in English-based courses in epidemiology in the USA and Europe. (Inevitably, some will have been omitted intentionally or unintentionally.