Frailty, physical performance and mortality in older patients with and without diabetic kidney disease: a longitudinal cohort study

Background: Declined renal function is associated with physical function impairment and frailty in a graded fashion. This study aimed to examine the relationship between renal function, frailty and physical performance with mortality in older patients with diabetes, while also determining their combined effects on patient outcome. Methods: : A longitudinal retrospective study was conducted in elderly patients with diabetes. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate of less than 60 ml/min, while the modified Rockwood frailty index (RFI) and physical function was determined by handgrip strength (HGS). Additionally, a timed up and go (TUG) test was assessed at baseline. Kaplan-Meier survival and Cox proportional hazard analyses were used to analyze the association between CKD, frailty, physical function and mortality. Results: : For the 921 enrolled patients, their mean age was 82.0 ± 6.7 years. After a median 2.92 (interquartile range [IQR] 1.06–4.43) year follow-up, the survival rate was 67.6% and 85.5% in patients with CKD and without CKD. The mortality hazard ratio (crude HR) with CKD was 5.92 for those with an RFI higher than 0.313 (95% CI 3.44–10.18), 2.50 for a TUG time longer than 21 seconds (95% CI 1.22–5.13), and 2.67 for an HGS lower than 10.57 kg in females or 20.4 kg in males (95% CI 1.12–6.37). After multivariate adjustment, the mortality hazard ratio for an RFI ≥0.313 was 5.34 (95% CI 2.23–12.80) in CKD patients, but not in non-CKD patients. In subgroup analysis, patients experiencing CKD and frailty, or physical function impairment, had the lowest survival proportion followed by only frailty/declined physical function, only CKD, non-CKD and non-frailty/non-physical impairment. Conclusions: : CKD, frailty and physical function impairment were all associated with an increased mortality risk in older patients with diabetes, while the combined effects of these 3 factors were seen on patient outcome.