Burden of Changes in Pill Appearance for Patients Receiving Generic Cardiovascular Medications After Myocardial Infarction: Cohort and Nested Case–Control Studies

Generic prescription drugs made by different manufacturers may vary in color or shape, and switching among these drug products may interrupt medication use.

To determine whether nonpersistent use of generic drugs among patients with cardiovascular disease after myocardial infarction (MI) is associated with inconsistent appearance of their medications.

Cohort and nested case–control studies.

Claims from a commercial health insurance database in the United States.

Patients discharged after hospitalization for MI between 2006 and 2011 who initiated treatment with a generic β-blocker, angiotensin-converting enzyme inhibitor, angiotensin II–receptor blocker, or statin. Case patients discontinued their index medication for at least 1 month; control patients continued treatment. Control patients were matched to case patients on therapeutic class, number of dispensings before nonpersistence, sex, and age.

Rates of changes in pill color and shape during the year after MI were calculated. Next, 2 refills preceding nonpersistence were evaluated to determine whether pill color or shape had changed. Odds of discordance among case and control patients were compared using conditional logistic regression.

A total of 29% of patients (3286 of 11 513) had a change in pill shape or color during the study. Statins had the most changes in appearance, whereas β-blockers had the fewest. A total of 4573 episodes of nonpersistence was matched to 19 881 control episodes. The odds of nonpersistence in case patients increased by 34% after a change in pill color (adjusted odds ratio, 1.34 [95% CI, 1.12 to 1.59]) and 66% after a change in pill shape (adjusted odds ratio, 1.66 [CI, 1.43 to 1.94]).

Only 3 categories of drugs indicated after MI were evaluated, and clinical outcomes were not addressed.

Variation in the appearance of generic pills is associated with nonpersistent use of these essential drugs after MI among patients with cardiovascular disease.

Agency for Healthcare Research and Quality and the Harvard Program in Therapeutic Science.