Longitudinal trends in copy-years viremia associated with mpox acquisition but not mpox severity in people with HIV.

OBJECTIVES: High viral load and low CD4+ cell count may be associated with increased risk of mpox acquisition. However, prior studies have not evaluated whether longitudinal trends in HIV lab measures, measured as the slope over time, are associated with mpox acquisition or severe mpox. Therefore, we evaluated whether longitudinal trends in CD4+ cell count (cells/μl), viral load (copies/ml), and copy-years viremia (CYV) (copies × years/ml) were associated with increased risk of mpox acquisition. DESIGN: We conducted a nested case-control study among participants in the DC Cohort, a longitudinal study on people with HIV (PWH) in Washington, DC. METHODS: Cases were defined as participants with mpox and were matched to five controls using risk set-sampling. Both two-stage modeling and joint modeling approaches were used to evaluate whether longitudinal trends in CD4+ cell count, viral load, and CYV were associated with mpox acquisition. RESULTS: We evaluated 53 cases of mpox and 248 matched controls, with 13.7% of cases having severe mpox. An increased slope of CYV was associated with an increased risk of mpox acquisition based on the joint modeling approach, after adjusting for AIDS and known antiretroviral regimen [hazard ratio (95% CI): 1.11 (1.04-1.18)]. CONCLUSION: Clinicians should consider a patient's entire history of viral load, not just viral load measured at one point in time, when evaluating risk of mpox.