Sero-prevalence of syphilis infection among people living with HIV in Sierra Leone: a cross-sectional nationwide hospital-based study

Background Globally, there were an estimated 7.1 million new syphilis infections in 2020, with more than 30% of these new infections reported in African countries such as Sierra Leone. Despite this, there is no HIV-specific syphilis screening program in Sierra Leone. Thus, data are needed to inform public health practice. In this study, we aimed to determine the prevalence of syphilis seropositivity and factors associated with syphilis seropositivity among people living with HIV (PLHIV).Methods A cross-sectional study was conducted at 10 health facilities in Sierra Leone, among adults with HIV, aged 18 years or older, from September 2022 to January 2023. Parameters of interest were collected including age, sex, marriage, antiretroviral therapy (ART) regimen, HIV viral load, duration of ART treatment, and hospital level of care. The syphilis antibody was detected by a rapid test based on immunochromatography assay. Data were analyzed using R-software version 4.2.3 (R Core Team, Vienna, Austria). Pearson's chi(2) test, Fisher's exact test and Kruskal-Wallis H test were applied to assess the differences in syphilis seropositivity between groups as appropriate. Univariate logistic regression and multivariate logistic regression analysis was used to assess factors associated with syphilis seropositivity. The level of statistical significance was set at P < 0.05.Results Of the 3082 PLHIV individuals in our study, 2294 (74.4%) were female and 2867 (93.0%) were receiving ART. With a median age of 36 years, 211 (6.8%, 95% CI 6.0-7.7) were positive for syphilis. The prevalence of syphilis was highest in people aged 60 years and over (21.1%, 95%CI 14.7-29.2), followed by people aged 50-60 years (15.5%, 95%CI 11.9-19.9) and in the widowed population (11.9%, 95%CI 8.9-15.8). There were no differences in syphilis seropositivity between gender, ART status, ART regimen, duration of ART, HIV viral load and hospital level of care. Older age (50-60 years: adjusted OR 3.49, 95%CI 2.09-5.85 P < 0.001; 60-100 years: adjusted OR 4.28, 95%CI 2.21-8.17, P < 0.001) was an independent predictor of seropositive syphilis.Conclusions We observed a high prevalence of syphilis among PLHIV. Older people and widowed population have higher syphilis seropositivity. Older age was an independent predictor of syphilis positivity. Therefore, we call for the integration of syphilis screening, treatment and prevention in HIV services.