Abstract
BACKGROUND: One of the largest-ever retail drug shortages began in 2018 when several angiotensin II receptor blockers (ARBs) for treating hypertension, heart failure, and chronic kidney disease-valsartan, losartan, and irbesartan-were recalled for carcinogenic impurities. The long-term consequences of the ARB shortages and whether certain groups experienced more adverse outcomes is unknown. OBJECTIVE: To evaluate changes in adherence and health outcomes after ARB recalls and to identify patients who experienced greater changes in access and adverse clinical outcomes. METHODS: Using an integrated claims and electronic health record dataset and a difference-in-differences design, we evaluated changes in the proportion of days covered (PDC) for ARBs and similar drugs (angiotensin-converting enzyme inhibitors [ACE-Is]), uncontrolled blood pressure, major cardiovascular event (MACE)-related acute care visits, and all-cause ambulatory care visits in the 12 months before vs 18 months after recalls for valsartan, losartan, and irbesartan users vs patients taking similar, nonrecalled drugs (ACE-Is, nonrecalled ARBs). Triple-difference models characterized heterogeneous associations by pre-recall patient demographic (race, ethnicity, age), clinical (baseline indication, mental health conditions), and adherence variables. RESULTS: Adjusting for pre-recall patient characteristics, we observed no significant changes in PDC for ARBs and ACE-Is (combined), uncontrolled blood pressure, or ambulatory care visits among 86,507 recalled ARB users vs 123,583 comparison drug users in the 18 months after the recalls. Following the recalls, medication switches increased on average by an additional 2.08 percentage points (p.p.) per quarter (95% CI = 2.01-2.15) for recalled ARB vs comparison drug users, a 195.9% relative increase. We observed the most switches in the 90-day period immediately after valsartan's recall (difference-in-difference: 9.48 p.p.; 95% CI = 9.36-9.59; relative change = 892%). Cumulatively, 55.2% of valsartan, 7.6% of losartan, and 18.9% of irbesartan users switched medications after 18 months. We observed an increase in the proportion of recalled ARB vs comparison patients who experienced medication gaps exceeding 30 days (1.13 p.p. per quarter on average; 95% CI = 0.97-1.30), which was most apparent after approximately 15 months (5 quarters). Although MACE-related acute care visits did not change in the quarter (90 days) immediately after valsartan's recall, we observed an increase of 1.40 additional visits per 1,000 recalled ARB vs comparison drug patients in each subsequent quarter, a 9.3% relative increase. Results were similar across most subgroups. CONCLUSIONS: The 2018 ARB recalls were associated with immediate changes in antihypertension medication use. Many patients transitioned to alternative medications. Although overall impacts on clinical outcomes were minimal and not statistically significant, small increases in medication gaps and MACE-related acute care visits among some patients occurred after more than 1 year. The ARB recalls may have been associated with fewer adverse events than other recent shortages owing to the widespread availability of alternative treatments in the same or similar drug class.