Interactive effects of intrinsic capacity and obesity on the KDIGO chronic kidney disease risk classification in older patients with type 2 diabetes mellitus

Background: Intrinsic capacity (IC) is a novel concept focusing on normal and healthy aging. The effect of IC on the risk of chronic kidney disease (CKD) according to KDIGO category in older type 2 diabetes mellitus (T2DM) patients has rarely been studied. We investigated whether a decline in IC is associated with the risk of CKD according to KDIGO 2012 categories. Methods: This is a cross-sectional study. The exposure variables (IC score and body mass index) and outcome variable (KDIGO categories of the risk of CKD) were collected at the same timepoint. A total of 2482 older subjects with T2DM managed through a disease care program were enrolled. The five domains of IC, namely locomotion, cognition, vitality, sensory, and psychological capacity were assessed. Based on these domains, the IC composite score was calculated. CKD risk was classified according to the KDIGO 2012 CKD definition. Univariate and multivariate analyses were used to assess the association between IC score and KDIGO categories of risk of CKD. Results: The KDIGO CKD risk category increased in parallel with IC score (p for trend < 0.0001). In multivariate analysis, compared to those with an IC score 0, the odds ratio of having a KDIGO moderately increased to very high risk category of CKD was 1.76 (1.31-2.37) times higher for those with an IC score of 2-5. Furthermore, an increased IC score was associated with a higher prevalence of moderate and severe obesity. Moreover, there was a synergistic interaction between IC score and obesity on the KDIGO moderately increased to very high risk category of CKD (synergy index = 1.683; 95% CI 0.630-3.628), and the proportion of the KDIGO moderately increased to very high risk category of CKD caused by this interaction was 25.6% (attributable proportion of interaction = 0.256). Conclusions: Our findings indicate that IC score may be closely related to the KDIGO moderately increased to very high risk category of CKD. In addition, there may be a synergistic interaction between IC score and obesity, and this synergistic interaction may increase the KDIGO CKD risk stage.