The Impact of HCV infection duration on HIV disease progression and response to cART amongst HIV seroconverters in the UK

Introduction The effect of HCV infection on HIV disease progression remains unclear; the effect of HCV infection duration on HIV disease progression is unknown. Methods We used data from a cohort of HIV seroconverters to investigate the effect of HCV infection duration on time from HIV seroconversion to CD4 <350cells/mm3, AIDS or death, censoring at the earlier of cART initiation or last clinic visit, adjusting for confounders and splitting data into follow up periods from HIV seroconversion (<2, 2-4 and >4 years). We additionally compared CD4 cell decline following HCV infection to that of mono-infected individuals with similar HIV infection duration by fitting a random effects model. In a separate analysis, we used linear mixed models to we examine the effect of HCV infection and its duration on CD4 increase over 48 weeks following cART. Results Of 1655 individuals, 97 (5.9%) were HCV co-infected. HCV<1 year was associated with a higher risk of endpoint in each follow-up period from HIV seroconversion (HR [95% CI] 2.58 [1.51, 4.41], p = 0.001; 3.80 [1.20, 12.03], p = 0.023; 2.03 [0.88, 4.71], p = 0.098 for <2, 2-4 and >4 years respectively), compared to mono-infected individuals. However, we found no evidence of an association for those with HCV>2 years (all p>0.89). Individuals experienced a somewhat greater decrease in CD4 count following HCV infection lasting 13 months, relative to individuals with HIV alone, (estimate =-3.33, 95% CI [-7.29, 0.63] cells/mm3 per month, p = 0.099). Of 1502 initiating cART, 106 (7.1%) were HCV co-infected, with no evidence of HCV duration at cART being associated with immunological response (p = 0.45). Conclusions The impact of HCV co-infection on HIV disease progression appears to be restricted to the first year after HCV infection.