Associations between Multimorbidity and the Risks of Cardiovascular Disease Events and All-Cause Mortality in Patients with Chronic Kidney Disease

INTRODUCTION: Multimorbidity, defined as the presence of two or more chronic conditions, is associated with poor outcomes and increased cardiovascular risk in the general population. However, the effect of multimorbidity on patients with chronic kidney disease (CKD), a group of patients already at high risk for cardiovascular disease, is not well understood. METHODS: We analyzed data from 4,420 patients with non-dialysis CKD enrolled in the Fukuoka Kidney disease Registry Study. We identified 23 comorbidities, including cardiometabolic and non-cardiometabolic conditions. The patients were categorized into four groups according to the number of comorbidities: Group 1 (0-1 comorbidities), Group 2 (2 comorbidities), Group 3 (3 comorbidities), and Group 4 (≥4 comorbidities). We examined the associations between the number of comorbidities and the incidence of major adverse cardiovascular events (MACE) and all-cause mortality using Cox proportional hazards models. RESULTS: Over a 5-year follow-up, 229 patients experienced MACE and 456 died. The risk of MACE increased with the number of comorbidities. The multivariable-adjusted hazard ratios (95% confidence intervals) for MACE were 1.40 (0.80-2.44) for Group 2, 2.27 (1.33-3.88) for Group 3, and 3.53 (2.11-5.91) for Group 4 compared with Group 1. The all-cause mortality risk also increased with the number of comorbidities, with adjusted hazard ratios of 1.13 (0.77-1.66), 1.75 (1.22-2.51), and 2.53 (1.80-3.54) for Groups 2, 3, and 4, respectively. CONCLUSION: In patients with CKD, multimorbidity is associated with an increased risk of MACE and all-cause mortality.