Agreement in the CARTaGENE cohort between self-reported medication use and claim data

To describe the agreement of self-reported medication use with claim prescription records and to ascertain factors associated with agreement between the two data sources.

Baseline data on self-reported medication use was extracted from CARTaGENE, a cohort study in Quebec, Canada, and from the provincial health insurance records (dispensation database) of the same individuals. Kappa statistics were used to estimate concordance beyond chance between the two data sources. Logistic regression models were adjusted to estimate the association between agreement and selected individual's characteristics (sex, age, education, region, income, utilization of health care system, and comorbidities).

Agreement between self-reported medication use and administrative data varied considerably across medication classes (kappa 0.54 for respiratory system and 0.91 for systemic hormonal preparations). Overall, agreement improved when a fixed time window of 90 days was used for exposure measurement. Sex, education level, frequency of health care use and the number of reported medications were associated with agreement.

Overall, there was a reasonable agreement between the two data sources, but important variations were found for the different drug classes. These results could be used by researchers to more accurately assess drug exposures using real-world data, which are increasingly important to regulators.