Factors associated with the first antiretroviral therapy modification in older HIV-1 positive patients

Rates of first antiretroviral therapy (cART) modifications are high in most observational studies. The age-related differences in treatment duration and characteristics of first cART modifications remain underinvestigated. With increasing proportion of older patients in HIV population it is important to better understand age-related treatment effects.

Patients were included into this analysis, if being cART naïve at the first visit at the clinic. Follow-up time was measured from the first visit date until first cART modification or 28 February 2013. First cART modification was defined as any change in the third drug component i.e. protease inhibitor (PI), non-nucleoside reverse transcriptase inhibitor (NNRTI), integrase inhibitor or fusion inhibitor. Cox proportional hazard models were used to identify factors related to first cART modification in three age groups: <30, 30-50 and >50.

In total 2027 patients with 14,965 person-years of follow-up (PYFU) were included. The oldest group included 136 patients with 1901, middle group 1202 with 8416 PYFU and youngest group consisted of 689 patients with 4648 PYFU. Median follow-up time was 5.8 (IQR 3.4-9.4) years, median time on first cART was 4.4 (IQR 2.1-8.5) years. 72.4 % of patients started PI-based and 26.1 % NNRTI-based regimen. In total 1268 (62.5 %) patients had cART modification (non-adherence 30.8 %, toxicity 29.6 %). Durability of first cART was the best in patients over 50 y.o. (log-rank test, p = 0.001). Factors associated with discontinuation in this group were late presentation (HR 0.45, [95 % CI 0.23-0.90], p = 0.02) and PI use (HR 2.17, [95 % CI 1.18-4.0], p = 0.01).

Rates of first cART modifications or discontinuation were comparable in all groups; however older patients were significantly longer on first cART regimen.