Table 3.

Study Design Considerations

Study designs	Advantages regarding CKDu	Disadvantages regarding CKDu
Prospective longitudinal studies	• Better view of the natural history of disease-incompletely understood in CKDu • Permit collection of a broader range of biomarkers over time • Exposure analysis over time • Test different hypotheses-etiology of CKDu is unknown	• Expensive-insufficient sample size may limit scope or power of study • Require stable residential populations-many affected workers are migrants • Results available only after years of follow-up
Retrospective case-control studies	• Comparisons of different locales and populations-which may explain different presentations in different regions • Comparisons of affected and unaffected members of the same community • Define susceptibility factors	• Depends heavily on the case definition-which is still being debated • Focus on late stage disease-interventions may be more valuable early in younger, less affected individuals • Survivor bias
Flexible study designs	• Case-only or case-control studies could be embedded within a prospective study	• Need sufficient power to examine variety of etiologies and biospecimens