Mpox clinical outcomes among people living with HIV and PrEP users: Findings from the MASH‐1 multicentre cohort study

Background Clinical outcomes of mpox (clade IIb) among people living with HIV (PWH) require clarification, particularly the role of immune status in determining disease severity. This multicentre study assessed differences in mpox clinical outcomes and hospitalization between PWH and PrEP users across European clinical settings. Methods Individuals with PCR‐confirmed mpox attending sexual health/HIV and infectious diseases services in 11 European countries between May 2022–December 2023 were included. Comparisons between PWH versus PrEP users were made using Chi‐square tests for categorical variables and t ‐tests for continuous variables; adjusted analyses accounting for study site used mixed‐effects logistic and Cox regression models. Univariable and multivariable models assessed key predictors. Results The proportion of clinic attendees with mpox ranged from 0.34%–3.07% across sites (946 PWH, 1054 PrEP users). Overall, 745/1989 (37%) individuals experienced at least one mpox‐related clinical complication. Median time to lesion resolution was 18 days (IQR 13–23). No deaths occurred. In unadjusted analysis, hospitalization was more frequent among PWH (57/946, 6% vs. 38/1054, 4%; p = 0.011), but this difference was not significant after site‐adjustment ( p = 0.389). Despite low numbers, among PWH with recent CD4 measurements, CD4 < 200/mm 3 was associated with significantly increased hospitalization (36% vs. 4%; p = 0.003). Immunosuppression was linked to hospitalization (aOR 3.00, 95% CI 1.03–8.78). Conclusions Mpox clinical outcomes were generally favourable in both PWH and PrEP users with adequate immune function. Severe immunosuppression, rather than HIV status per se, was associated with hospitalization risk. These findings support prioritized clinical monitoring for individuals with advanced immunodeficiency and highlight the importance of immune status assessment in mpox management.