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Abstract Background and Aims Chronic kidney disease (CKD) is known to be associated with impaired cognitive function, with lower estimated glomerular filtration rate (eGFR) associated with poorer cognitive performance 1. Though CKD prevalence increases with age, the association with cognitive disorders is not entirely explained by age distribution. Cognitive impairment in CKD is multifactorial with potential biochemical, cardiovascular, medication and socio-economic mediators. As with other long-term conditions, self-management of kidney disease becomes more difficult in the context of cognitive impairment. The prevalence and associations of cognitive impairment in people referred to secondary care with CKD is not well described. This study therefore aimed to identify the prevalence and associations of impaired cognitive function among a referred population of people with CKD. Method The NURTuRE-CKD cohort recruited 2996 people with an estimated Glomerular Filtration Rate (eGFR) of 15-59 ml/min/1.73 m2 (CKD-EPI equation) or ≥60 ml/min/1.73 m2 with a urine albumin to creatinine ratio (uACR) of more than 30 mg/mmol referred to one of 16 secondary care nephrology clinics. Baseline data were collected between 2017-2019 including sociodemographic, anthropometric, biochemical, and clinical information and included the 6-item cognitive impairment test (6-CIT), a commonly used cognitive screening instrument. Other scores collected included the Hospital Anxiety and Depression score (HADS), EQ-5D-5L as a health-related quality of life (HRQoL) measure and Single Item Literacy Screener (SILS). Prevalence of impaired cognitive function (defined as 6-CIT score of 8 or more out of 28) was calculated and multivariable mixed effects logistic regression models used to identify associations with impaired cognitive function. The multivariable model was adjusted for known factors impacting cognitive impairment and recruitment region as a random effect. Results A total of 2743/2996 (91.6%) participants had complete 6-CIT data. Median age was 66 years and 41% were female. Median eGFR was 34 ml/min/1.73 m2. Prevalence of cognitive impairment was 8.7% (240/2743), rising from 5.3% in those 65 to 10.6% in those ≥65 years. eGFR was not associated with cognitive impairment on univariate analysis. After adjustment, greater likelihood of cognitive impairment was independently associated with older age, Asian and Black ethnicity (compared to white), and limited health literacy. Lower likelihood of cognitive impairment was associated with better HRQoL and higher education attainment (Figs 1 and 2). Conclusion Cognitive impairment was relatively common in this cohort of people with CKD. Similar associations for cognitive impairment with age and education in a CKD population had also been identified in CKD-REIN—a prospective cohort of CKD patients recruited from secondary care in France, though using a different cognitive function measure. Associations of limited health literacy, ethnicity, and HRQoL with cognitive impairment were identified risk factors that could aid clinicians in recognising high risk patients to prompt screening and improve management. Follow-up data will allow longitudinal analyses to explore associations between impaired cognitive function and health-related outcomes, between kidney function and change in cognitive function and risk factors for change in cognitive function, including the role of inflammatory markers. Limitations: this analysis only used baseline data so causality cannot be established, 6-CIT is a screening rather than diagnostic tool for cognitive impairment.
Lee et al. (Wed,) studied this question.
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