Background and purpose: Preceding infection as an important risk factor for ischemic stroke has been reported but neglected for hemorrhagic stroke, especially in young and middle-aged patients. This study investigates whether newly diagnosed leptospirosis is associated with an increased risk of stroke.
Methods: We identified 3699 in-patients who were aged ≥18 years and newly diagnosed with leptospirosis. We also randomly selected a comparison cohort 14 796 in-patients from the general population by using a propensity score matching method (at a 1:4 ratio). We analyzed the risks of stroke by using Cox proportional hazard regression models.
Results: The adjusted hazard ratio (HR; 95% CI) of stroke for the leptospirosis group was 1.14 (0.93-1.38; P=0.200) as opposed to the comparison group after adjusting sex, age, and comorbidities. However, adjusted HR (95% CI) of ischemic stroke and hemorrhagic stroke was 1.01 (0.80-1.29) and 1.58 (1.12-2.23), respectively. The strength of association between leptospirosis and hemorrhagic stroke remained statistically significant after variation of leptospirosis and stroke definitions. The post hoc subgroup analysis indicated that a patient with leptospirosis had a significantly greater risk of hemorrhagic stroke in male (adjusted HR, 1.62 [95% CI, 1.08-2.44]) and individuals between age 18 and 39 (adjusted HR, 3.67 [95% CI, 1.33-10.14]). The risk of hemorrhagic stroke among people with leptospirosis was highest in the first 2 years after diagnosis (adjusted HR, 1.97 [95% CI, 1.15-3.38]).
Conclusions: A 2.49-fold risk of stroke was found among the leptospirosis cohort of aged younger than 39 years. Age acted as an effect modifier between the leptospirosis and risk of new-onset stroke.
Keywords: cohort studies; hemorrhagic stroke; infections; ischemic stroke; leptospirosis.