Background
Maintenance drugs are used to treat chronic conditions. Several classes of maintenance drugs have attracted attention because of their potential to affect susceptibility to and severity of COVID-19.
Methods
Using claims data on 20% random sample of Part D Medicare enrollees from April to December 2020, we identified patients diagnosed with COVID-19. Using a nested case-control design, non-COVID-19 controls were identified by 1:5 matching on age, race, sex, dual-eligibility status and geographical region. We identified usage of angiotensin-converting enzyme inhibitors (ACEI), angiotensin-receptor blockers (ARB), warfarin, direct factor Xa inhibitors, clopidogrel, famotidine and hydroxychloroquine based on Medicare prescription claims data. Using extended Cox regression models with time-varying propensity score adjustment we examined the independent effect of each study drug on contracting COVID-19. For severity of COVID-19, we performed extended Cox regressions on all COVID-19 patients, using COVID-19-related hospitalization and all-cause mortality as outcomes. Covariates included gender, age, race, geographic region, low-income indicator and co-morbidities. To compensate for indication bias related to the use of hydroxychloroquine for the prophylaxis or treatment of COVID-19, we censored patients who only started on hydroxychloroquine in 2020.
Results
Up to December 2020, our sample contained 374,229 Medicare patients over 65 who were diagnosed with COVID-19. Among the COVID-19 patients, 209,208 (55.9%) were on at least one study drug. The three most common study drugs were ACEI 97,872 (26.1%), ARB 83,329 (22.3%) and clopidogrel 38,203 (10.2%). Current users of ACEI, ARB, warfarin, direct factor Xa inhibitor and clopidogrel were associated with reduced risk of getting COVID-19 (3-13%), and reduced risk of dying after a COVID-19 diagnosis (8-19%). Famotidine did not show consistent significant effects. Hydroxychloroquine did not show significant effects after censoring of recent starters.
Conclusions
Maintenance use of ACEI, ARB, warfarin, direct factor Xa inhibitor and clopidogrel was associated with reduction in risk of acquiring COVID-19 and dying from it.