Assessment of predictors of viraemia copy-years in people with HIV/AIDS following initiation of combination antiretroviral therapy
Recent studies have suggested that higher overall cumulative HIV viraemia exposure measured as viraemia copy years (VCY) is a better predictor of all-cause mortality compared with routine plasma HIV RNA viral load (pVL) and CD4 cell counts. The ability to identify those individuals at risk of higher VCY would be clinically relevant. We sought to assess predictors of VCY in Australian HIV Observational database (AHOD) participants following initiation of ART.
Methods: Analyses were based on patients recruited to AHOD who had received ≥24 weeks of ART. We established VCY, a measurement akin to smoking pack-years, after 1, 3, 5 and 10 years of ART by calculating the area under the pVL time series. We used multivariable generalised estimating equations to determine predictors of VCY. We evaluated model performance by comparing area under the sensitivity/specificity curve, and compared the performance of a baseline predictor model with a time updated predictor model to discriminate patients with high VCY. We defined high VCY as VCY>100,000 copy-years.
Results: Of the 3495 AHOD patients recruited, 2073(60%), 1667(48%), 1267(36%) and 638(18%) were eligible for analysis at 1, 3, 5 and 10 years of ART respectively. Mean (95% confidence interval) VCY at 1, 3, 5, 10 years of ART was 204(182-229), 1862(1622-2138), 5129(4467-6026) and 19953(16596-24547) copy-years respectively. Several factors were associated (significant at α=0.05) with higher VCY. These included: younger age, earlier periods of ART initiation, lower CD4 cell counts, mono/duo ART experience prior to ART initiation, protease inhibitor as initial ART anchor agent, high baseline pVL, increased number of ART modifications and increased total treatment interruption time. Models that included time updated information were better at discriminating persons with higher VCY compared to baseline predictor models.
Conclusion: Our results show one can reasonably identify patients at risk of higher VCY following ART initiation using typical clinical patient characteristics and factors.
