Analyzing and synthesizing information from a multiple-study database

An important public-health issue receiving much discussion in the literature today concerns whether there is an ideal relative weight associated with minimum mortality for all populations. Standards developed by WHO and U.S. organizations propose that ideal weights be determined by Body Mass Index, a single measure incorporating weight and height ($$BMI = \frac{{wt\left( {kg} \right)}}{{ht{{\left( m \right)}^2}}}$$). They recommend BMIs of ≤ 25 for all. To better understand the relationship between BMI and mortality in diverse populations and to discern whether a single BMI of minimum mortality is appropriate, we examine person-level data from 18 studies.