Factors associated with low-level viraemia in people with HIV starting antiretroviral therapy: A Swedish observational study.

OBJECTIVE: Low-level viraemia (LLV) occurs in some people with HIV (PWH) receiving antiretroviral therapy (ART) and has been linked to inferior treatment outcomes. We investigated factors associated with LLV in a nationwide cohort of Swedish PWH starting ART. METHODS: Participants were identified from the InfCareHIV register, with the following inclusion criteria: ART initiation 2006-2017, age >15 years, ≥4 viral load (VL) results available and no documented treatment interruptions or virologic failure (≥2 consecutive VL ≥200 copies/ml) during follow-up. Starting from 6 months after ART initiation, participants were followed for 24 months and categorised as viral suppression (VS; VL <50 copies/ml) or LLV (≥2 consecutive VL 50-199 copies/ml). We analysed the association between the following factors and LLV using multivariable logistic regression: sex, age, pre-ART VL and CD4 count, ART regimen, country of birth, HIV-1 subtype and transmission category. RESULTS: Among 3383 participants, 3132 (92.6%) had VS and 251 (7.4%) had LLV. In univariable analyses, factors associated with LLV were male sex, higher age, lower pre-ART CD4 count, higher pre-ART VL and ART regimen. After adjustment, the following factors were associated with LLV (adjusted odds ratio; 95% confidence interval): male sex (1.6; 1.1-2.3), higher pre-ART VL (2.7; 2.2-3.3), pre-ART CD4 count <200 cells/µl (1.6; 1.2-2.2), protease inhibitor (PI)-based regimen (1.5; 1.1-2.1), non-standard ART (2.4; 1.0-5.5) and injecting drug use (2.0; 1.1-3.7). CONCLUSION: Among Swedish PWH, LLV during ART was associated with markers of HIV disease severity before starting ART, male sex, injecting drug use and use of PI-based or non-standard ART regimens.