The syndemic effect of HIV/HCV co-infection and mental health disorders on acute care hospitalization rate among people living with HIV/AIDS: a population-based retrospective cohort study

Our primary objective was to examine the syndemic effect of HIV/HCV co-infection and mental health disorders (MHD) on the acute care hospitalization rate among people living with HIV (PLW-HIV) in British Columbia, Canada. Secondarily, we aimed to characterize the longitudinal trends in the aforementioned rate, while controlling for the effect of several factors. In this retrospective cohort study, individuals were antiretroviral therapy-naïve, ≥ 18 years old, initiated treatment between 1 January 2000 and 31 December 2014, and were followed for at least 6 months until 31 December 2015 or last contact. The outcome was acute care hospitalization rate (every 6-month interval) per individual. The exposure was the interaction between HIV/HCV co-infection and MHD. Generalized non-linear mixed-effects models were built. Of the 4046 individuals in the final analytical sample, 1597 (39%) were PLW-HIV without MHD, 606 (15%) were people living with HIV and HCV (PLW-HIV/HCV) without MHD, 988 (24%) were PLW-HIV with MHD, and 855 (21%) were PLW-HIV/HCV with MHD. The adjusted rate ratios for acute care hospitalizations were 1.31 (95% [confidence interval] 1.13–1.52), 2.01 (95% CI 1.71–2.36), and 2.53 (95% CI 2.20–2.92) for PLW-HIV with MHD, PLW-HIV/HCV without MHD, and PLW-HIV/HCV with MHD, respectively, relative to PLW-HIV without MHD. The HIV/HCV co-infection and MHD interaction demonstrated a significant effect on the rate of acute care hospitalization, particularly for PLW-HIV/HCV with MHD. Implementing widely accessible integrative care model best practices may address this public health challenge.