Relationship between prevalence rate ratios and odds ratios in cross-sectional studies.

Methods for estimating prevalence ratios in cross-sectional studies.

OBJECTIVE To empirically compare the Cox, log-binomial, Poisson and logistic regressions to obtain estimates of prevalence ratios (PR) in cross-sectional studies. METHODS Data from a population-based cross-sectional epidemiological study (n = 2072) on elderly people in Sao Paulo (Southeastern Brazil), conducted between May 2003 and April 2005, were used. Diagnoses of dementia, possible cases ...

Making sense of odds and odds ratios.

Odds and odds ratios are hard for many clinicians to understand. Odds are the probability of an event occurring divided by the probability of the event not occurring. An odds ratio is the odds of the event in one group, for example, those exposed to a drug, divided by the odds in another group not exposed. Odds ratios always exaggerate the true relative risk to some degree. When the probability...

Mischievous Odds Ratios

Overestimation of risk ratios by odds ratios in trials and cohort studies: alternatives to logistic regression.

Believability of relative risks and odds ratios in abstracts: cross sectional study.

OBJECTIVE To compare the distribution of P values in abstracts of randomised controlled trials with that in observational studies, and to check P values between 0.04 and 0.06. DESIGN Cross sectional study of all 260 abstracts in PubMed of articles published in 2003 that contained "relative risk" or "odds ratio" and reported results from a randomised trial, and random samples of 130 abstracts ...