Cognitive impairment in elderly renal inpatients: an under-identified phenomenon

Cognitive impairment is a common but under-recognised problem in patients with chronic kidney disease, and is likely to become more significant as this patient population ages.

This cross-sectional study focussed on inpatients aged ≥65 years at a tertiary renal unit, and consisted of two parts. Part 1 (n = 25) considered whether cognitively impaired inpatients were being identified and being referred to memory services. In Part 2 (n = 105) two different cognitive function tests were attempted (6-CIT, MMSE).

In Part 1, cognitive function tests were attempted in only 4 patients at admission and 1 patient subsequently. No patients were referred to memory services. In Part 2, 6-CIT was abnormal (score ≥8) in 61.4%, and MMSE was abnormal (score <27) in 79.5% (score 21-26: 28.9%, 15-20: 28.9%, 10-14: 13.3%, <10: 8.4%). There was a close correlation between MMSE and 6-CIT (R(2) = 0.735). Only 7.2% of those assessed had a documented cognitive deficit prior to admission.

This is the first study looking at cognition in elderly inpatients with chronic kidney disease. There appears to be a much higher rate of cognitive impairment than expected and this is largely unidentified. These deficits are likely to have a major impact on both inpatient and outpatient management.