Blood cadmium levels and overactive bladder in middle-aged and older adults in the United States: Insights from NHANES 2007-2020 data.

Cadmium is a common environmental pollutant associated with various health risks. Its neurotoxic, muscle-damaging, and pro-inflammatory properties may be related to overactive bladder (OAB), though few studies have assessed its impact on urinary function. This study aimed to examine the potential link between cadmium exposure and OAB. Using data from the 2007-2020 National Health and Nutrition Examination Survey (NHANES), we analyzed adults aged 40 and older (n = 15,467) in a cross-sectional design. OAB was defined by the refined Overactive Bladder Symptom Score (OABSS). Weighted multivariate logistic regression examined the associations between blood cadmium levels and OAB and its components. Age and gender stratifications were performed, and restricted cubic splines (RCS) were used to explore non-linear associations between blood cadmium and OAB. Sensitivity analyses and co-exposure analyses with other pollutants were conducted to assess OAB definition stability, subgroup differences, and exposure collinearity. The prevalence of OAB was 26.2%. While blood cadmium showed a small, non-significant positive association with overall OAB, it was inversely associated with nocturia severity (OR = 0.85, 95% CI 0.74-0.98, p < 0.05). Blood cadmium was also linked to more severe urinary incontinence in the 50-59 age group and among non-Hispanic Black adults. A non-linear association between blood cadmium and OAB was observed (p for nonlinearity = 0.016, p < 0.05). In co-exposure analyses, cadmium remained a dominant and independent factor. These findings suggest that cadmium exposure may have a complex association with OAB and may relate differently to its various components. Further research is needed to explore these relationships.