Alexander C. Fanaroff, MD, MHS Assistant Professor of Medicine, Division of Cardiovascular Medicine University of Pennsylvania

How Best to Measure Patient Persistence with Medications? Self Report or Pharmacy Fill? Interview with:

Alexander C. Fanaroff, MD, MHS Assistant Professor of Medicine, Division of Cardiovascular Medicine University of Pennsylvania

Dr. Fanaroll

Alexander C. Fanaroff, MD, MHS
Assistant Professor of Medicine, Division of Cardiovascular Medicine
University of Pennsylvania What is the background for this study?

Response: This is a secondary analysis of the ARTEMIS, a cluster randomized trial of copayment assistance for P2Y12 inhibitors in patients that had myocardial infarction. One of the primary endpoints of ARTEMIS was persistence with P2Y12 inhibitors: Did the patient continue to take a P2Y12 inhibitor over the entire 1 year following MI? In ARTEMIS, we captured persistence data in two ways, patient report and pharmacy fill records. What we did in this study was to look at the agreement between persistence as measured by these two methods. What are the main findings?

Response: Overall, 15% of patients self-reported non-persistence, but 48% of patients were non-persistent by pharmacy fill data. When we looked at agreement between the methods, the two methods quite frequently did not agree: 50% of patients were persistent by both methods, 13.5% were non-persistent by both methods, 34.8% reported that they were persistent but were non-persistent by pharmacy fill, and 1.8% reported that they were non-persistent but were actually persistent by pharmacy fill records. Both methods are subject to bias: Self-report is subject to social desirability bias (where patients misrepresent medication taking behavior to please investigators) and recall bias (where patients don’t remember their medications). Pharmacy fill data is subject to missing data if a pharmacy is not included in the database, or other reasons.

Because of these biases, we next tried to understand which method of measuring persistence — pharmacy fill records or self-report — was “correct.” To do this, we used two other methods of measuring persistence that were captured in ARTEMIS: copayment assistance vouchers and P2Y12 inhibitor serum drug levels. We had serum drug levels for a random sample of patients in ARTEMIS, and we found limited agreement beyond chance between serum drug levels and persistence as measured by pharmacy fill and patient report, which did not help sort out which method was more “correct.” In the intervention arm, patients used vouchers to have copayments for P2Y12 inhibitors waived, and we were able to track when vouchers were used. Using the voucher data, 20% of patients that self-reported persistence but were characterized by pharmacy fill data as non-persistent actually were persistent, suggesting that pharmacy fill data underestimates persistence by roughly that amount.

Lastly, we looked at clinical outcomes by persistence category, and found that patients persistent by both methods had the best outcomes, patients non-persistent by both methods had the worst outcomes, and patients with discordant persistence had outcomes intermediate between concordantly persistent and non-persistent patients. What should readers take away from your report?

Response: Electronic health records increasingly have a mechanism for enabling physicians to check pharmacy fill records for patients to track persistence with medications. Our results show that this data is important, as it identifies more patients than self-report, but that it needs to be interpreted somewhat cautiously: Many patients non-persistent by pharmacy fill are actually persistent.

The best way to understand persistence is to incorporate both patient self-report and pharmacy fill data, recognizing that patients non-persistent by both methods will have the worst outcomes. What recommendations do you have for future research as a result of this work?

Response: Currently, health systems employ a number of interventions to increase medication persistence. Future research should look at the best way to target these interventions to patients that are non-persistent with medications, including methods that use both patient report and pharmacy fill data.

No disclosures relevant to this research


Fanaroff AC, Peterson ED, Kaltenbach LA, et al. Agreement and Accuracy of Medication Persistence Identified by Patient Self-report vs Pharmacy Fill: A Secondary Analysis of the Cluster Randomized ARTEMIS Trial. JAMA Cardiol. Published online March 04, 2020. doi:10.1001/jamacardio.2020.0125


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Last Modified: Mar 5, 2020 @ 2:29 am


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