Systemic immune-inflammatory index and its association with female sexual dysfunction, specifically low sexual frequency, in depressive patients: Results from NHANES 2005 to 2016.

Sexual dysfunction, particularly in females, is a complex issue influenced by various factors, including depression and inflammation. The Systemic immune-inflammation index (SII), an inflammatory biomarker, has shown associations with different health conditions, but its relationship with female sexual dysfunction (FSD) remains unclear. This study aimed to investigate the association between SII and FSD in the context of depression, utilizing low sexual frequency as an assessment indicator. Data from the National Health and Nutrition Examination Survey (NHANES) 2005 to 2016, involving 1042 depressed female participants, were analyzed. FSD, indicated by low sexual frequency, and SII, derived from complete blood count results, were assessed. Logistic regression and subgroup analyses were conducted, considering demographic and health-related factors. A total of 1042 individuals were included in our analysis; 11.5163% of participants were categorized as having FSD, which decreased with the higher SII tertiles (tertile 1, 13.8329%; tertile 2, 13.5447%; tertile 3, 7.1839%; p for trend < 0.0001). Multivariate linear regression analysis showed a significant negative association between SII and FSD [0.9993 (0.9987, 0.9999)]. This negative association in a subgroup analysis is distinctly and significantly present in the Mexican American subgroup [0.9959 (0.9923, 0.9996)], while it does not reach statistical significance in other racial categories. Furthermore, the association between SII and FSD was nonlinear; using a 2-segment linear regression model, we found a U-shaped relationship between SII and FSD with an inflection point of 2100 (1000 cells/µL). In summary, in depressed individuals, a higher SII is independently associated with a decreased likelihood of FSD, emphasizing the potential role of inflammation in female sexual health.