The influence of age-associated comorbidities on responses to combination antiretroviral therapy in older people living with HIV

Introduction: Multiple comorbidities among HIV-positive individuals may increase the potential for polypharmacy causing drug-to-drug interactions and older individuals with comorbidities, particularly those with cognitive impairment, may have difficulty in adhering to complex medications. However, the effects of age-associated comorbidities on the treatment outcomes of combination antiretroviral therapy (cART) are not well known. In this study, we investigated the effects of age-associated comorbidities on therapeutic outcomes of cART in HIV-positive adults in Asian countries. Methods: Patients enrolled in the TREAT Asia HIV Observational Database cohort and on cART for more than six months were analysed. Comorbidities included hypertension, diabetes, dyslipidaemia and impaired renal function. Treatment outcomes of patients ≥50 years of age with comorbidities were compared with those <50 years and those ≥50 years without comorbidities. We analysed 5411 patients with virological failure and 5621 with immunologic failure. Our failure outcomes were defined to be in-line with the World Health Organization 2016 guidelines. Cox regression analysis was used to analyse time to first virological and immunological failure. Results: The incidence of virologic failure was 7.72/100 person-years. Virological failure was less likely in patients with better adherence and higher CD4 count at cART initiation. Those acquiring HIV through intravenous drug use were more likely to have virological failure compared to those infected through heterosexual contact. On univariate analysis, patients aged <50 years without comorbidities were more likely to experience virological failure than those aged ≥50 years with comorbidities (hazard ratio 1.75, 95% confidence interval (CI) 1.31 to 2.33, p < 0.001). However, the multivariate model showed that age-related comorbidities were not significant factors for virological failure (hazard ratio 1.31, 95% CI 0.98 to 1.74, p = 0.07). There were 391 immunological failures, with an incidence of 2.75/100 person-years. On multivariate analysis, those aged <50 years without comorbidities (p = 0.025) and age <50 years with comorbidities (p = 0.001) were less likely to develop immunological failure compared to those aged ≥50 years with comorbidities. Conclusions: In our Asia regional cohort, age-associated comorbidities did not affect virologic outcomes of cART. Among those with comorbidities, patients <50 years old showed a better CD4 response.