Cognitive impairment and health outcomes in non-dialysis chronic kidney disease: a systematic review and meta-analysis

Abstract

Background: Cognitive impairment is prevalent in individuals with chronic kidney disease (CKD), but its effects on health outcomes remain unclear. While cognitive impairment can affect self-management, its role in CKD has been insufficiently explored. This systematic review aimed to examine the association between cognitive impairment and health outcomes or self-management ability among persons with CKD.

Methods: Searches were performed in June 2024 on Embase, MEDLINE, CINAHL, PsycINFO, Web of Science, PubMed and grey literature databases for longitudinal or cross-sectional studies examining associations between cognitive impairment (using any validated measure) and health outcomes or ability to self-manage in adults with CKD not on kidney replacement therapy. Health outcomes included mortality, kidney disease progression, hospitalization and healthcare utilization, cardiovascular and cerebrovascular events, and health-related quality of life (HRQoL). Risk of bias was assessed using the ROBINS-E ('Risk of bias in non-randomized studies of exposure') tool.

Results: Fourteen studies were included. Cognitive impairment was associated with increased all-cause and cardiovascular mortality, higher risk of cardiac arrhythmia, stroke and transient ischaemic attack, lower HRQoL, and higher healthcare utilization. Mixed results were seen in studies examining the association between cognitive impairment and kidney disease progression. No studies with self-management measures as an outcome were identified.

Conclusions: Cognitive impairment is associated with poor health outcomes in persons with CKD, although evidence was limited for some outcomes. No causal link could be established due to potential residual confounding by frailty or shared comorbidities. Further research is required to explore potential causal pathways and the role of cognitive impairment in CKD self-management.

Keywords: chronic kidney disease; cognitive impairment; health outcomes; mortality; self-management.

Figure 1:

Flow chart of study identification process. Figure adapted from PRISMA 2020 Guidelines (Page MJ 2021). *Some studies had more than one reason for exclusion.

Figure 2:

Forest plot showing the results of fixed and random effects of meta-analysis of all-cause mortality.

Figure 3:

Forest plot showing summary statistics for all other outcomes with reported hazard, risk and odds ratios. Hazard ratio >1 and relative risk >1 reflects higher likelihoods in the group with cognitive impairment. Odds ratio >1 for Medication Adherence outcome reflects poorer medication adherence. Odds ratio >1 for Dialysis Modality Choice reflects higher likelihood of choosing a non-self-care dialysis modality if there was a lower (worse) cognitive score. Odds ratio >1 for HRQoL reflects higher likelihood of reporting a poor outcome (i.e. issues with domain) in comparison with participants with normal cognition.

Figure 4:

Summary of risk of bias assessment. Domain 1: risk of bias due to confounding. Domain 2: risk of bias arising from measurement of the exposure. Domain 3: risk of bias in selection of participants into the study (or into the analysis). Domain 4: risk of bias due to post-exposure interventions. Domain 5: risk of bias due to missing data. Domain 6: risk of bias arising from measurement of the outcome. Domain 7: risk of bias in selection of the reported result.