OBJECTIVE

To develop two checklists for the quality of observational studies of incidence or risk factors of diseases.

STUDY DESIGN AND SETTING

Initial development of the checklists was based on a systematic literature review. The checklists were refined after pilot trials of validity and reliability were conducted by seven experts, who tested the checklists on 10 articles.

RESULTS

The checklist for studies of incidence or prevalence of chronic disease had six criteria for external validity and five for internal validity. The checklist for risk factor studies had 6 criteria for external validity, 13 criteria for internal validity, and 2 aspects of causality. A Microsoft Access database produced automated standardized reports about external and internal validities. Pilot testing demonstrated face and content validities and discrimination of reporting vs. methodological qualities. Interrater agreement was poor. The experts suggested future reliability testing of the checklists in systematic reviews with preplanned protocols, a priori consensus about research-specific quality criteria, and training of the reviewers.

CONCLUSIONS

We propose transparent and standardized quality assessment criteria of observational studies using the developed checklists. Future testing of the checklists in systematic reviews is necessary to develop reliable tools that can be used with confidence.