Hi dear prof. doctor Niludi

In bivariate and mutlivariate regression analysis you can get crude and adjusted odd`s ratio (statistics).

Also there is an Odd`s ratio in meta analysis from case control studies (Methodology). While hazard ratio is being in case of survival analysis (statistics).

I think odds ratios in meta-analysis is a measure of prevalence, usually applied for case-control studies while risk ratios in meta-analysis is a measure of incidence, overtime, usually applied for cohort comparative studies. Odds ratios may be close to risk ratios in case of rare events.

Odds Ratio can be converted to Risk Ratio, especially for rare events, but Risk Ratio is not typically converted back to Odds Ratio due to the differences in their underlying calculations and assumptions. But consider using some parameters like random effect model and test for heterogeneity.

IYH Dear Niludi Yasaratna

Converting an odds ratio (OR) to a hazard ratio (HR) isn't straightforward because they measure different things and are used in different contexts.

Odds ratios are commonly used in case-control studies and some types of cohort studies, particularly when the outcome is common. Hazard ratios, on the other hand, are used in survival analysis to compare the time-to-event between groups.

While there isn't a direct mathematical conversion between OR and HR, under certain assumptions, particularly when the event rate is low, the OR can approximate the relative risk (RR), and under further assumptions, the HR can also approximate the RR. However, this approximation may not hold when event rates are high.

If you have studies reporting both ORs and HRs and you want to pool them in a meta-analysis, it's generally not advisable to directly convert one to the other due to their different interpretations and the potential for bias introduced by such conversions.

Thank you all for your valuable information.