Association Between HIV-1 RNA Detection Status and HBV DNA Detection: A Patient-Level Retrospective Longitudinal Molecular Study from Istanbul, Türkiye

Background/Objectives: HIV and hepatitis B virus (HBV) share major transmission routes and may coexist in the same individual, making coordinated molecular assessment clinically important. Methods: This retrospective longitudinal laboratory-based study evaluated the patient-level association between HIV-1 RNA detection and HBV DNA detection using routine molecular testing data from a tertiary-care hospital in Istanbul, Türkiye. HIV-1 RNA and HBV DNA results obtained between 1 January 2022 and 1 August 2026 were linked at the patient level. A total of 5303 unique patients had HIV-1 RNA testing and 30,981 unique patient records had HBV DNA testing; these were separate source populations, and 529 individuals with results available for both molecular assays constituted the primary analytical cohort. Results: Among the 529 patients, HIV-1 RNA was detected at least once in 246 (46.5%), while HBV DNA was detected at least once in 147 (27.8%). HBV DNA detection occurred in 83/246 (33.7%) patients with at least one detectable HIV-1 RNA result and in 64/283 (22.6%) patients with no detectable HIV-1 RNA in any available measurement (OR, 1.74; 95% CI, 1.19–2.56; p = 0.005). However, the association was attenuated after adjustment for age and sex and was no longer statistically significant (adjusted OR, 1.28; 95% CI, 0.84–1.94; p = 0.255). HIV-1 RNA magnitude and HIV-1 RNA categories were not significantly associated with HBV DNA detection, and no significant correlation was observed between same-day HIV-1 RNA and HBV DNA levels (Spearman’s ρ = 0.161; p = 0.387) or between the nearest quantitative measurements obtained within ±30 days (ρ = 0.171; p = 0.245). Because treatment exposure and adherence information were unavailable, the observed molecular patterns could not be interpreted as direct measures of treatment response or treatment failure. Conclusions: These findings indicate that HIV-1 RNA detection status or magnitude should not be used as a surrogate for HBV DNA detection and support independent, clinically indicated HBV assessment in people living with HIV.