Background: Chronic kidney disease (CKD) affects more than one third of older adults, and is a strong risk factor for vascular disease and cognitive impairment. Cognitive impairment can have detrimental effects on the quality of life through decreased treatment adherence and poor nutrition and results in increased costs of care and early mortality. Though widely studied in hemodialysis populations, little is known about cognitive impairment in patients with pre-dialysis CKD. Methods: Multicenter, cross-sectional, prospective cohort study including 385 patients with CKD stages G4-G5. Cognitive function was measured with a validated tool called the Montreal Cognitive Assessment (MoCA) as part of a comprehensive frailty assessment in the Canadian Frailty Observation and Interventions Trial. Cognitive impairment was defined as a MoCA score of ≤24. We determined the prevalence and risk factors for cognitive impairment in patients with CKD stages G4-G5, not on dialysis. Results: Two hundred and thirty seven participants (61%) with CKD stages G4-G5 had cognitive impairment at baseline assessment. When compared to a control group, this population scored lower in all domains of cognition, with the most pronounced deficits observed in recall, attention, and visual/executive function (p < 0.01 for all comparisons). Older age, recent history of falls and history of stroke were independently associated with cognitive impairment. Conclusions: Our study uncovered a high rate of unrecognized cognitive impairment in an advanced CKD population. This impairment is global, affecting all aspects of cognition and is likely vascular in nature. The longitudinal trajectory of cognitive function and its effect on dialysis decision-making and outcomes deserves further study.

BackgroundReactivation of latent Mycobacterium tuberculosis infection (LTBI) is a health concern for patients on dialysis or receiving a kidney transplant, as these patients are often immunosuppressed. The most frequently used test for LTBI screening in this population is the tuberculin skin test (TST). The diagnostic accuracy (sensitivity and specificity) of the TST in a contemporary North American or Western European dialysis population is unknown.ObjectivesOur objective was to determine the diagnostic accuracy and clinical utility of the two-step TST in patients receiving dialysis.DesignThis is a retrospective cohort study.SettingThis study is set at four tertiary dialysis units across Winnipeg, Manitoba.PatientsThere are 483 chronic hemodialysis and peritoneal dialysis patients in the study.MeasurementsThe measurements are sensitivity and specificity of the TST with respect to abnormal chest X-ray.MethodsAll patients received a two-step TST and assessment of risk factors for prior tuberculosis (TB) infection between February 2008 and December 2008. This cohort was retrospectively linked to our tuberculosis registry to ascertain if prophylaxis was received for LTBI.ResultsAt an induration cutoff of 5 mm, 62 (13 %) patients had a positive two-step TST. Patients with a known Bacillus Calmette-Guérin (BCG) vaccination were more likely to test positive (50 % of those with a positive TST had a BCG versus 34 % with a negative TST, p = 0.05). Using a diagnostic gold standard of an abnormal chest X-ray as a proxy for LTBI, the sensitivity of the TST was only 14 % and the specificity was 88 %. Only 8 of 62 patients with a positive TST (13 %) received prophylaxis for LTBI. None of the patients who tested negative were treated.LimitationsThere is a lack of a truly accurate gold standard for LTBI.ConclusionsThe TST has limited diagnostic and clinical utility for LTBI screening in patients on dialysis. Further research into the diagnostic accuracy of interferon-gamma release assays and a revision of LTBI screening guidelines in patients on dialysis should be considered.Electronic supplementary materialThe online version of this article (doi:10.1186/s40697-016-0119-4) contains supplementary material, which is available to authorized users.