Pharmacy claims data versus patient self-report to measure contraceptive method continuation.

OBJECTIVE

To compare self-reported 12-month continuation of oral contraceptive pills (OCPs), patch, and ring versus continuation by pharmacy claims data.

STUDY DESIGN

Women in the Contraceptive CHOICE Project who chose OCPs, the patch, or the ring as their initial method were included. Continuation was assessed by periodic telephone survey and by obtaining prescription claims data. Continuation was defined as no gap of more than 30 days. Kaplan-Meier survival functions were used to estimate continuation rates and cumulative unintended pregnancy rates. Kappa statistic assessed the level of agreement between self-report and claims data.

RESULTS

We analyzed 1510 women who initiated use by 3 months and provided information on discontinuation. Of OCP users, 59% continued their method at 12 months by self-report versus 38% by pharmacy claims. Patch and ring users had self-reported/pharmacy continuation of 45%/28% and 57%/37%, respectively. Kappa coefficients and their 95% confidence intervals between the two measurements were 0.46 (0.40, 0.52), 0.54 (0.39, 0.68), and 0.54 (0.47, 0.61) for OCP, patch, and ring, respectively. Among women who self-reported continuation, unintended pregnancy rates were 0.4% in those who continued by pharmacy claims versus 4.9% in those who discontinued according to claims data.

CONCLUSION

Contraceptive continuation rates differ by self-report versus pharmacy claims with women overestimating their continuation by self-report.

IMPLICATIONS

This article directly compares contraception continuation rates by self-report and by pharmacy claims data. The study suggests that previously reported continuation rates from survey data overestimate specific method use.