Sexual HIV transmission is more likely to occur when HIV viral load (VL) exceeds 1,500 copies/mL. We assessed percentage of person-time spent with VL above 1500 copies/mL (pPT>1500) for adult patients in HIV care.
We analyzed data from medical records of the HIV Outpatient Study (HOPS) cohort participants seen at nine United States (U.S.) HIV clinics during 2000-2014. Included patients had ≥1 HOPS clinic visit and ≥2 VLs during 2000-2014. We assessed pPT>1500 by analyzing values and time intervals between consecutive VL pairs per published methods (AIDS 2015, 29:947–954) and incorporating ART prescription data. Generalized estimating equations assuming a Poisson model and robust variance estimator were used to test for trend, and estimate the pPT>1500 and the corresponding 95% confidence intervals (CI) for patients in clinical and demographic strata.
The 5,873 patients contributed 37,794 person years [py], 86% on ART, with a median 15 VLs (interquartile range: 7-27) per patient. Overall pPT>1500 was 24% (CI: 23-25), decreasing from 37% in 2000 to 10% in 2014, P for trend <0.001. More patients used ART, including integrase inhibitors, over time (Figure). During the time when ART was prescribed, pPT>1500 was 16% overall, decreasing from 32% in 2000 to 7% in 2014, P for trend <0.001. pPT>1500 was higher in patients <35 vs. ≥50 years old (31% vs. 16%), women vs. men (31% vs. 22%), black vs. white and Latino/Hispanic patients (33% vs. 20% and 24%, respectively), and in patients who started observation (baseline) with public insurance vs. private (31% vs. 21%), CD4 cell counts <500 cells/mm³, and VLs>1500 copies/mL. In adjusted regression analyses, the significant correlates of pPT>1500 included time-updated ‘no ART (off ART) status’ (Relative Risk [RR] 3.5, CI: 3.3-3.7), and baseline characteristics: VL>1500 (RR 2.3, CI: 2.1-2.4), age <35 years (RR 1.5, CI: 1.4-1.6) and 35-49 years (RR 1.3, CI: 1.2-1.5) vs. ≥50 years, having public insurance (RR 1.2, CI: 1.2-1.3) vs. private, and being non-Hispanic black (RR 1.2, CI: 1.1-1.3) vs. white.
Adult U.S. patients in routine HIV care spent substantially less time with VLs over 1500 copies/mL from 2000 to 2014, a period characterized by the shift toward universal ART initiation and continuous improvements in ART regimens. The observed trends imply a decreasing risk of HIV transmission from persons in HIV care over the last decade and the need to focus interventions on subsets of patients more consistently viremic.