Impact of CKD and COPD co-existence on mortality, vascular dementia, and Alzheimer’s dementia; a comparative cohort study

BACKGROUND: Chronic kidney disease (CKD) and chronic obstructive pulmonary disease (COPD) are common conditions associated with increased risks of mortality and cognitive impairment. However, the association between COPD and dementia outcomes in patients with CKD remains incompletely understood. METHODS: We conducted a retrospective observational cohort study using the TriNetX Global Collaborative Network, including patients aged 18-80 years with CKD stages 3-5, excluding those with prior dialysis, transplantation, dementia, or mild cognitive impairment before cohort entry. Two cohorts were identified: CKD with COPD, defined using classical ICD-10 COPD codes (J41-J44), and CKD without COPD. A secondary sensitivity analysis used a broader respiratory disease definition including asthma, bronchiectasis, and other chronic respiratory conditions. Cohorts were propensity score matched (1:1) for demographic characteristics, comorbidities, smoking exposure, and laboratory parameters. Outcomes included all-cause mortality, non-Alzheimer's dementia, and Alzheimer's disease, assessed over a maximum follow-up of 5 years using Kaplan-Meier and Cox proportional hazards analyses. RESULTS: Two cohorts were identified: CKD with COPD (n = 270 566) and CKD without COPD (n = 821 399). After propensity score matching, 234 317 patients remained in each cohort. CKD with COPD was associated with a higher observed risk of mortality compared with CKD alone (18.5% vs. 14.5%; HR 1.17; 95% CI 1.16-1.19; p < 0.001). The composite outcome of non-Alzheimer's dementia was also more frequent in the CKD with COPD cohort (4.6% vs. 3.9%; HR 1.07; 95% CI 1.04-1.10; p < 0.001). No significant association was observed for vascular dementia alone or mild cognitive impairment alone. Alzheimer's disease incidence was low in both cohorts, and lower observed hazards were identified in the COPD cohort (HR 0.85; 95% CI 0.80-0.91; p = 0.002), although these findings should be interpreted cautiously given the relatively short follow-up and higher competing mortality in the COPD cohort. CONCLUSIONS: Among patients with CKD, coexisting COPD was associated with higher observed risks of mortality and non-Alzheimer's dementia during follow-up. Further longitudinal studies with longer follow-up and competing-risk methodology are warranted.