Importance: Medication non-adherence is highly costly and leads to worse disease control and outcomes. However, knowledge about medication adherence is often disconnected from prescribing decisions, and this disconnect may lead to inappropriate increases in medications and higher risks of adverse events. Objectives: To evaluate the association between medication non-adherence and the likelihood of increases in the intensity of medication regimens for two chronic conditions, hypertension and type 2 diabetes. Design: Cohort Study. Setting and Participants: This study used US national pharmacy claims data for Medicare Part D (ages ≥ 65) and commercial (ages 50-64) plans to evaluate medication adherence and its association with the likelihood of receiving an increase in medication intensity for patients with hypertension and/or oral diabetes medication fills. Patients had an index fill for hypertension (N = 2,536,638) and/or oral diabetes (N = 701,376) medications in January 2015. Medication fills in the follow-up period from August 2015 to December 2016 were assessed for increases in medication regimen intensity. Main Outcome(s) and Measure(s): The proportion of days covered (PDC) over 181 days was used as a measure for patient's medication adherence before a medication addition, medication increase, or dosage increase. Differences in the likelihood of experiencing an escalation in medication intensity was considered between patients with a PDC < 80% vs. PDC ≥ 80%. Results: Among Medicare Part D and commercial plan patients filling hypertension and/or oral diabetes medications, non-adherent patients were significantly more likely to experience an intensification of their medication regimens (p < 0.001). Conclusions and Relevance: This study found a significant association between non-adherence to medications and a higher likelihood of patients experiencing potentially inappropriate increases in treatment intensity. Sharing of objective patient refill data between retail pharmacies and prescribers can enable prescribers to have more targeted discussions with patients about their adherence and overall treatment plan. Additionally, it can increase safe medication prescribing and plausibly reduce adverse drug events and healthcare costs while improving patient health outcomes.
Keywords: Medicare Part D; medication adherence; medication regimen intensity.