Neurosyphilis among people with and without HIV infection:A Danish nationwide prospective, population-based cohort study 2015–2021

Background: Comparative data on clinical presentation, laboratory characteristics, treatment, and outcome of neurosyphilis (NS) in people living with HIV (PLWH) and NS patients without HIV are scarce. Methods: Nationwide, population-based, prospective cohort study on all adults with NS diagnosed between 2015 and 2021 at departments of infectious diseases in Denmark. Results: We identified 108 patients with NS, which equals a yearly incidence of 0.3/100,000 adults. The median age was 49 years, 85 (79%) were male, 43 (40%) were men having sex with men and 20 (22%) were PLWH. Ninety-five (88%) had early NS, 37 (34%) had ocular or ocular and otogenic NS, and 27 (25%) had symptomatic meningitis. Most common symptoms were visual disturbance (44%), skin rash (40%), fatigue (26%) and chancre (17%). Median CSF leukocyte count was 27 × 106 cells/L. PLWH less often had neurological deficits (p = 0.02). Unfavorable outcome was observed in 23 (21%) at discharge of whom 0 were PLWH (p = 0.01). Among the 88 NS patients without HIV a CSF leukocyte count of ≥ 30 × 106 cells/L was associated with unfavorable outcome (OR = 3.3 (95% confidence interval: 1.1–10.4)). Conclusions: PLWH with NS have better outcomes than NS patients without HIV infection.