Sex differences in incidence and fatality of severe fever with thrombocytopenia syndrome: A comparative study based on national surveillance data of China

Abstract

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne emerging infectious disease with an increasingly global concern. Sex difference in infectious diseases is an important public health problem. A comparative study on sex differences in SFTS incidence and fatality was conducted using all laboratory-confirmed cases in mainland China during 2010−2018. Females had significantly higher average annual incidence rate (AAIR) with a risk ratio (RR) of 1.17 (95% confidence interval [CI] 1.11–1.22; p ˂ 0.0001), but significantly lower-case fatality rate (CFR) with an odd ratio of 0.73 (95% CI 0.61–0.87; p = 0.001). The significant differences in AAIR and CFR were observed in age groups of 40–69 and 60–69 years, respectively (both p < 0.05). There was a rising incidence and declining CFR along with epidemic years. After adjusting for age, temporal and spatial distribution, agricultural setting and onset-to-diagnosis interval, the female-to-male difference in either AAIR or CFR remained significant. The underlying biological mechanisms of the sex-based differences that the females are more prone to get the disease, but less likely for a fatal outcome deserve further investigations.