Monocyte count predicts low-level viremia in people living with HIV receiving antiretroviral therapy: A retrospective cohort study

Low-level viremia (LLV) remains a clinical challenge in people living with HIV (PLWH) receiving antiretroviral therapy (ART), with its pathogenesis and predictors not fully understood. Recent evidence suggests a role for monocytes in HIV persistence and immune activation. However, the clinical significance of monocyte count (MONO) as a predictive biomarker for LLV has not been fully elucidated. This study aimed to evaluate whether baseline (MONO) is associated with the risk of developing LLV in PLWH. We conducted a retrospective cohort study involving 671 PLWH on ART at Ningbo Yinzhou No. 2 Hospital. Participants were categorized into tertiles based on baseline MONO. The primary outcome was the incidence of LLV. Cox proportional hazards regression analyses were performed to assess the association between MONO and LLV, adjusting for potential confounders. Sensitivity analyses were conducted stratified by baseline HIV viral load and ART regimen. In addition, MONO trajectories were analyzed using linear mixed models. During a median follow-up of 2.5 years, the incidence of LLV was 14.2% (56.9 cases per 1000 person-years). Higher baseline MONO was independently associated with an increased risk of LLV (HR = 3.708, 95% CI: 1.918-7.169 for middle vs low tertile; HR = 4.695, 95% CI: 2.491-8.849 for high vs low tertile; both P < .001), regardless of baseline viral load or ART regimen. Sensitivity analyses confirmed the robustness of these findings across different subgroups. LLV was associated with persistently elevated MONO. Monocyte count is an independent risk factor for the development of LLV in PLWH receiving ART. These findings provide preliminary evidence that MONO may serve as a readily accessible biomarker for identifying individuals at increased risk.