Correlation between medication adherence using proportion of days covered and achieving viral suppression in patients...

BACKGROUND: Medication adherence plays an important role for patients living with HIV and achieving the treatment goal of viral suppression. A goal adherence rate of at least 90% has been previously cited and endorsed; however, studies have demonstrated that lower rates of adherence may still lead to high rates of viral suppression. Adherence rates are increasingly being used by payers to assess pharmacy performance. OBJECTIVE: To determine if there is a difference in the odds of achieving viral suppression with a proportion of days covered (PDC) at least 90% compared with patients with lower PDC levels. Additionally, to determine if demographic factors, including age, ethnicity, sex, primary antiretroviral regimen type, payer type, primary pharmacy location, and refill assistance program enrollment, impact the odds of achieving viral suppression. METHODS: This retrospective observational study included patients who were aged 18 years or older; were diagnosed with HIV; had at least 2 occurrences of dispensed antiretrovirals between July 1, 2020, and June 30, 2021, within the health system; and had at least 1 HIV-RNA viral load recorded between these dates. PDC was calculated at the generic product identifier (GPI) level. For patients receiving multiple GPIs in this period, a weighted average PDC was calculated. A logistic regression analysis was performed, and odds ratios were calculated with 95% confidence for each demographic factor to determine correlation with viral suppression. RESULTS: 1,629 patients were included. Overall, 1,516 (93.1%) patients were virally suppressed. 106 (6.5%) patients had a PDC lower than 50% and 639 (39.2%) had a PDC of at least 90%. Of the patients with a PDC lower than 50%, 80 (75.5%) achieved viral suppression as did 617 (96.6%) patients with a PDC of at least 90%. Age and insurance type significantly impacted viral suppression. No statistically significant difference was found between the odds of achieving viral suppression until PDC was below 75%. Patients with a PDC of less than 50% or a PDC of 50% to less than 75% were less likely to achieve viral suppression than patients with a PDC of at least 90% (P < 0.001). CONCLUSIONS: Patients with adherence rates above 75% achieve similar results compared with patients with adherence rates above 90%. High population viral suppression may be achieved with as few as 39.2% of patients achieving a PDC greater than 90%. Using these results, the Pharmacy Quality Alliance and other guidance setting entities should consider lowering the at least 90% threshold as well as providing further guidance on how payers should use results and network benchmarking when creating pharmacy quality performance measures.