Syphilis and ischemic stroke: Old question revisited by a nationwide cohort study

<jats:sec><jats:title>Background and purpose:</jats:title><jats:p> In the era of easily available antibiotic use, this study provides epidemiological evidence for a re-examination of the relationship between syphilis and ischemic stroke (IS). </jats:p></jats:sec><jats:sec><jats:title>Methods:</jats:title><jats:p> Patients aged 18 years and older with newly diagnosed syphilis were included (n = 1585) from 2000 to 2012, and participants without syphilis in the control group (n = 6340) were matched by propensity score (age, sex, index year, insured amount, urbanization, seasons, and comorbidities). The Cox proportional hazard model was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) of IS. Five different Cox regression models, sensitivity analyses, and negative control were conducted to test our findings. </jats:p></jats:sec><jats:sec><jats:title>Results:</jats:title><jats:p> In all, 1585 patients (1055 (66.56%) men; mean (SD) age, 49.59 (20.32) years) had syphilis, and 3.8% had new-onset IS. The syphilis group had a higher risk of IS than the controls (adjusted HR, 1.35; 95% CI, 1.01–1.80; p value < 0.05) after full adjustment. Serial sensitivity analyses yielded consistent results. </jats:p></jats:sec><jats:sec><jats:title>Conclusion:</jats:title><jats:p> Syphilis patients have higher risk of IS, and our data raise the question of implementation of prophylactic treatment for IS. </jats:p></jats:sec>