Antiretroviral Treatment Gaps and Adherence Among People with HIV in the US Medicare Program

Approximately one-quarter of people with HIV (PWH) in the U.S. receive coverage through the Medicare program; however, no prior real-world study has examined antiretroviral therapy (ART) gaps and adherence and associated factors in this population. This retrospective cohort analysis used 2013-2018 national Medicare fee-for-service claims data to identify all PWH initiated on a new ART regimen including protease inhibitors [PI], non-nucleoside reverse transcriptase inhibitors [NNRTIs], or integrase strand transfer inhibitors [INSTIs] between 1/1/2014 and 12/31/2017. Study outcomes included ART adherence (based on proportion of days covered [PDC]), continuous treatment gaps ranging from 1 to 6 days to >= 180 days, and discontinuation (continuous gap >= 90 days) in the 12-month follow-up period. Multivariable regressions were used to assess factors associated with ART adherence and discontinuation. The final sample included 48,627 PWH (mean age: 54.5 years, 74.4% male, 47.5% White, 89.8% disabled). Approximately 53.0% of PWH had a PDC >= 0.95, 30.2% had a PDC between 0.70 and < 0.95, and 16.8% had PDC < 0.70. Treatment gaps of at least >= 7-days (55.2%) and >= 30-days (26.2%) were common and 10.1% PWH discontinued treatment. Younger age, female sex, Black race, higher comorbidity score, mental health conditions, and substance use disorder were associated with higher odds of lower adherence and discontinuation (all p-values < 0.05). In conclusion, suboptimal adherence and treatment gaps in ART use were commonly observed among PWH in Medicare. Interventions and policies to mitigate barriers to adherence are urgently needed in this population to both improve their survival and increase the potential for ending the HIV epidemic in the US.