Association of albumin-corrected anion gap with all-cause and cardiovascular mortality in overactive bladder patients

Overactive bladder (OAB) is a symptom syndrome characterized by urgency, often accompanied by frequency and nocturia. It significantly impacts patients' quality of life and imposes a substantial economic burden. The albumin-corrected anion gap (ACAG), an important indicator reflecting the body's acid-base balance and electrolyte disturbances, has predictive value in various chronic diseases. However, its association with the prognosis of OAB patients has not been adequately studied. This study aims to explore the relationship between ACAG levels and all-cause mortality and cardiovascular mortality in OAB patients. A total of 6592 OAB patients (representing 31,072,714 individuals in the U.S. population) from the 2005-2018 NHANES database were included based on strict inclusion criteria. The relationship between ACAG and mortality risk was analyzed using a multivariable-adjusted Cox proportional hazards regression model, with non-linear associations assessed using restricted cubic splines (RCS). Additionally, Kaplan-Meier survival analysis and subgroup analyses were conducted to evaluate the association between ACAG and mortality risk. During an average follow-up of 79.5 months, 1332 all-cause deaths and 352 cardiovascular deaths occurred. In the fully adjusted model, each 1-unit increase in ACAG was associated with an 11% higher risk of all-cause mortality (HR = 1.11, 95% CI 1.06-1.15) and an 8% higher risk of cardiovascular mortality (HR = 1.08, 95% CI 1.01-1.16). Analysis based on ACAG tertiles revealed that, compared to the lowest tertile, the highest tertile was associated with an 65% increased risk of all-cause mortality (HR = 1.65, 95% CI 1.33-2.04) and a 43% increased risk of cardiovascular mortality (HR = 1.43, 95% CI 1.22-1.63), showing a significant dose-response relationship (all-cause mortality P for trend < 0.001; cardiovascular mortality P for trend = 0.028). RCS analysis indicated a linear positive correlation between ACAG and mortality risk. Elevated ACAG levels are significantly associated with both all-cause and cardiovascular mortality in OAB patients, with this association being consistent across various subgroups. This study provides the first evidence of the potential value of ACAG as a prognostic biomarker for OAB patients, offering new insights for clinical risk stratification and personalized treatment strategies.