Validation of the electronic prescription as a method for measuring treatment adherence in hypertension.

Objective: To validate electronic prescriptions (e-prescriptions) as a method for measuring treatment adherence in patients with hypertension.

Methods: This prospective study initially included 120 patients treated for hypertension in primary care centers. Adherence was measured using the gold standard, the medication event monitoring system (MEMS), versus the index test, the e-prescription program, at baseline and at 6, 12, 18 and 24 months. We calculated the adherence rate using the MEMS and the medication possession ratio (MPR) for the e-prescriptions. We considered patients adherent if they had an adherence rate of 80% to 100%. To validate the e-prescription, we obtained measures of diagnostic accuracy, the Kappa concordance index, and the area under the ROC curve (AUC).

Results: We included 102 patients. Overall adherence was 77.4% by MEMS (95%CI: 66.8-88) and 80.4% (95%CI: 70.3-90.5) by MPR. At 24 months, sensitivity was 87% and specificity, 93.7%. The AUC was 0.903 (95%CI: 0.817-0.989).

Conclusion: Measures of treatment adherence were not significantly different between e-prescription and gold standard at most visits, and the e-prescription showed good discriminatory diagnostic capacity.

Practice Implications: If patients are included in an e-prescription program for at least 2 years, e-prescription is an inexpensive method to measure adherence in hypertension.