Increased fat mass index is associated with decreased glomerular filtration rate estimated from cystatin C. Data from Malmö Diet and Cancer cohort

Abstract

Background This study aims to describe associations of obesity and CKD in a Swedish urban population. The impact of fat mass, from bioimpedance analysis, on eGFR based on cystatin C and/or creatinine is studied. Methods 5049 participants from Malmö Diet and Cancer Study the cardiovascular arm (MDCS‐CV) with available body mass composition (single frequency bioimpedance analysis) and cystatin C measured at baseline were selected. Body mass index (kg/m2) was used to define overweight/obesity. eGFR was calculated using cystatin C (eGFRCYS) and creatinine (eGFRCR) equations: Chronic Kidney Disease Epidemiology Collaboration 2012 (CKD-EPICR, CKD-EPICYS, CKD-EPICR-CYS), eGFRCYS based on Caucasian, Asian, pediatric, and adult cohorts (CAPA), the Lund-Malmö revised equation (LMrev), and Modified Full Age Spectrum creatinine-based equation (EKFCCR). Two different fat mass index (FMI) z-scores were calculated: FMI z-scoreLarsson and FMI z-scoreLee. Results Lower eGFRCYS and eGFRCR-CYS following multiple adjustments were prevalent in overweight/obese subjects. Increase in FMI z-scoreLarsson or FMI z-scoreLee was related to decrease in predicted CAPA, CKD-EPICYS, CKD-EPICR-CYS and CAPA-LMrev equation. Conclusion eGFRCYS, in contrast to combined eGFRCR-CYS and eGFRCR, demonstrate the strongest association between FMI and kidney function.