Risk Ratios and Odds Ratios for Common Events in Cross-sectional and Cohort Studies

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

The relative merits of risk ratios and odds ratios.

When a study outcome is rare in all strata used for an analysis, the odds ratio estimate of causal effects will approximate the risk ratio; therefore, odds ratios from most case-control studies can be interpreted as risk ratios. However, if a study outcome is common, the odds ratio will be further from 1 than the risk ratio. There is debate regarding the merits of risk ratios compared with odds...

Risk ratios and odds ratios--what are they?

A risk ratio (sometimes called relative risk, both abbreviated to RR) and an odds ratio (OR) are ways of expressing a comparison between two proportions. For example, in this paper, there are two randomised groups in the trial, women in the lateral position and women in the supported sitting position in the passive second stage of labour. The authors wanted to compare the proportions of instrum...

Relative Risk and Odds Ratios Examples

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 ...