[Cross-sectional associations between reproductive lifespan duration and urinary albumin-creatinine ratio]

Objective: To investigate the association between reproductive lifespan duration (RLD) and urinary albumin-creatinine ratio (UACR) in a Chinese postmenopausal population. Methods: This cross-sectional study included 11 055 naturally postmenopausal women from seven regions of China from May to December 2011. RLD was divided into four groups. Propensity score matching was performed to reduce bias, and logistic regressions and stratifications were conducted to investigate the association between RLD and increased UACR (≥30 mg/g). Mediation effect analysis was performed to quantify the effect of RLD on cardiovascular disease (CVD) induced by elevated UACR. Results: There were 2 373 participants with a RLD of 18-31 years, 2 888 participants with a RLD of 32-34 years, 2 472 participants with a RLD of 35-36 years, and 3 322 participants with a RLD of 37-50 years. The shortest RLD (18-31 years) group was characterized with older age (P<0.001), a higher incidence of CVD (P=0.025), and the highest level of UACR (P<0.001). After adjusting for confounders, women with a longer RLD (37-50 years group) exhibited a lower risk of UACR elevation compared with those with the shortest RLD (18-31 years group) (OR=0.72, 95%CI 0.64-0.82, P<0.001). Every 1-year extension in RLD was linked to a 2% reduction in the risk of UACR elevation (OR=0.98, 95%CI 0.97-0.99, P<0.001). Stratified analysis revealed a more significant association between RLD and UACR in women who were a normal weight (P=0.003) or overweight (P=0.001), in those without CVD history (P=0.001), and in those with impaired estimated glomerular filtration rate (P=0.004). The mediation casual analysis showed that 3.0% of proteinuria inducing CVD events was mediated by RLD (P=0.048). Conclusion: A longer RLD (37-50 years) is associated with a lower UACR in Chinese postmenopausal women.