The Emerging Risk Factors Collaboration is a collation of primary data from over 1 million participants in over 100 prospective studies which focuses on risk markers for major cardiovascular mobidity and mortality. The meta-analysis of individual participant data from multiple prospective epidemiological studies provides scope for detailed investigation of exposure-risk relationships, but involves a number of statistical challenges. Analyses are principally based on Cox proportional hazards regression models stratified by sex, undertaken in each study separately. Estimates of unadjusted and adjusted exposure-risk relationships, and interactions, are combined over studies using random-effects meta-analysis. Methods for assessing the shape of risk-exposure associations and the proportional hazards assumption have been developed or extended. Measurement error in exposures and confounders is addressed through the analysis of repeat exposure measurements to estimate corrected regression coefficients.
Further details regarding the statistical analyses undertaken in the ERFC can be found in:
Statistical methods for the time-to-event analysis of individual participant data from multiple epidemiological studies. Int J Epidemiol. 2010;39:1345-1359. [PubMed]
ERFC methods used in assessment of the predictive ability of risk models and the incremental predictive ability of added risk predictors are detailed in:
Assessing risk prediction models using individual participant data from multiple studies. Am J Epidemiol. 2014 Mar 1;179(5):621-32. [PubMed]