New prescription of antihyperglycemic agents among patients with diabetes in Germany: Moderate concordance between health insurance data and self-reports.

PURPOSE: To analyze the concordance of new prescription of antihyperglycemic agents between two data sources: patients' self-reports and statutory health insurance (SHI) data among patients with diabetes.

METHODS: Within a cross-sectional study, 494 patients with diabetes were interviewed if and which new prescriptions of diabetes medication they received within the last 3 or 6 months. SHI data for 12 months were linked to cover these periods. For the agreement measurement, SHI data was set as reference, and kappa, positive predictive value (PPV), and sensitivity were calculated for single Anatomical Therapeutic Chemical (ATC) codes and cumulated code groups.

RESULTS: The number of new prescriptions within 3 or 6 months was low, with 5.5% (n = 27) for Metformin/self-report being the highest. Contingency tables were unbalanced and showed large numbers in the no/no-cells. Regarding non-agreement, we found new prescriptions slightly more often in SHI data only than in self-reports only, with insulin and metformin representing an exception. Agreement results were moderate with large confidence intervals (CI). The values for cumulated "all drugs in diabetes" were: kappa = 0.58 (95% CI: 0.51-0.65), PPV = 62.0 (53.4-70.2), sensitivity = 55.6 (47.3-63.6).

CONCLUSIONS: Patients reported a low number of new prescriptions within the last 3 or 6 months. In general we found moderate agreement and in case of non-agreement that self-report no/SHI yes was slightly more frequent than vice versa. These results were based on small case numbers, but could nevertheless be considered when collecting self-reported information on the prescription of antihyperglycemic agents.