Association between Multimorbidity and Kidney Function among Patients with Non-Dialysis-Dependent CKD: The Fukuoka Kidney Disease Registry Study

Aim: Individuals with chronic kidney disease (CKD) have a high prevalence of comorbidities, including cardiovascular disease (CVD) and its risk factors. However, epidemiological results to assess the association between multimorbidity and kidney function among the CKD population remains limited. Methods: We performed a cross-sectional analysis of the association between 23 comorbid conditions and reduced kidney function in 4,476 patients with non-dialysis-dependent CKD enrolled in a multicenter cohort in Japan. Reduced kidney function was defined as an estimated glomerular filtration rate of ≤ 60 mL/min/1.73 m(2). Results: The mean age of patients was 67 years (male, 56.0%). The prevalence of hypertension, diabetes mellitus, dyslipidemia, prior CVD, cancer, and bone fracture, which are the major comorbidities, was 83.3%, 28.7%, 45.9%, 23.3%, 12.7%, and 6.3%, respectively. Multivariable-adjusted analyses revealed that age, male sex, hypertension, dyslipidemia, prior CVD, body mass index, urinary protein excretion, and underlying kidney disease were independent factors associated with reduced kidney function. Importantly, the odds ratios (ORs) for reduced kidney function increased linearly as the number of major comorbid conditions increased (OR for 1–2 conditions: 2.22, 95% confidence interval [CI]: 1.65–2.97; OR for 3–4 conditions: 3.04, 95% CI: 2.12–4.37; OR for ≥ 5 conditions: 4.37, 95% CI: 1.75–10.9). The upward trend in OR was more pronounced with cardiovascular comorbidities but not significant with non-cardiovascular comorbidities. Conclusions: In conclusion, we observed an independent association between cardiovascular comorbidity and its risk factors and reduced kidney function. The results of this study highlight the importance of managing multimorbidity among patients with CKD.