Issues in pooling of data from separate cohort studies and proposed solutions
| Issues in pooling data | Approach |
| Recruitment strategies | Stratification of analyses per cohort |
| Comparability of phenotype measurements | Selection of standardised phenotypes |
| Comparability of environmental exposures | Stratification of analyses per cohort and correction for confounding exposures in regression analysis |
| Different ethnicities | Evaluation of genetic effect separately in each ethnic group (in this study: exclusion of non-Dutch participants) |
| Allele frequencies | Checking of spurious effects caused by differences in allele frequencies between studies |
Criteria are deduced from 25 and modified to apply to pooling data from cohort studies.