Understanding the mechanisms underlying the differences in renal decline between men and women may improve sex-specific clinical monitoring and management. To this end, we aimed to compare the slope of renal function decline in older men and women in CKD stage 4-5, taking into account informative censoring related to the sex-specific risks of mortality and dialysis initiation.
The EQUAL study is an observational prospective cohort study in stage 4-5 CKD patients ≥65 years not on dialysis. Data on clinical and demographic patient characteristics were collected between April 2012 to December 2018. eGFR was calculated using the CKD-EPI equation. eGFR trajectory by sex was modelled using linear mixed models, and joint models were applied to deal with informative censoring.
We included 7801 eGFR measurements in 1682 patients over a total of 2911 years of follow-up. Renal function declined by 14.0% (95% CI 12.9%-15.1%) on average each year. Renal function declined faster in men (16.2% per year, 95% CI 15.9%-17.1%) compared with women (9.6% per year, 95% CI 6.3%-12.1%), which remained largely unchanged after accounting for various mediators, and for informative censoring due to mortality and dialysis initiation. Diabetes was identified as an important determinant of renal decline specifically in women.
In conclusion, renal function declines faster in men compared with women, which remained similar after adjustment for mediators, and despite a higher risk of informative censoring in men. We demonstrate a disproportional negative impact of diabetes specifically in women.