Evaluation of Screening Tests for Cognitive Impairment in Patients Receiving Maintenance Hemodialysis.

BACKGROUND: Neurocognitive testing shows that cognitive impairment is common among patients receiving maintenance hemodialysis. Identification of a well performing screening test for cognitive impairment might allow for broader assessment in dialysis facilities and thus optimal delivery of education and medical management. METHODS: From 2015 to 2018, in a cohort of 150 patients on hemodialysis, we performed a set of comprehensive neurocognitive tests that included the cognitive domains of memory, attention, and executive function to classify whether participants had normal cognitive function versus mild, moderate, or severe cognitive impairment. Using area-under-the-curve (AUC) analysis, we then examined the predictive ability of the Mini Mental State Examination, the Modified Mini Mental State Examination, the Montreal Cognitive Assessment, the Trail Making Test Part B, the Mini-Cog test, and the Digit Symbol Substitution Test, determining each test's performance for identifying severe cognitive impairment. RESULTS: Mean age was 64 years; 61% were men, 39% were black, and 94% had at least a high-school education. Of the 150 participants, 21% had normal cognitive function, 17% had mild cognitive impairment, 33% had moderate impairment, and 29% had severe impairment. The Montreal Cognitive Assessment had the highest overall predictive ability for severe cognitive impairment (AUC, 0.81); a score of ≤21 had a sensitivity of 86% and specificity of 55% for severe impairment, with a negative predictive value of 91%. The Trails B and Digit Symbol tests also performed reasonably well (AUCs, 0.73 and 0.78, respectively). The other tests had lower predictive performances. CONCLUSIONS: The Montreal Cognitive Assessment, a widely available and brief cognitive screening tool, showed high sensitivity and moderate specificity in detecting severe cognitive impairment in patients on maintenance hemodialysis.

Blood Pressure and Cognitive Decline in Prevalent Hemodialysis Patients.

BACKGROUND: Hypertension is associated with cognitive decline in the general population. It is unclear what impact blood pressure (BP) has on cognitive decline in patients receiving maintenance hemodialysis (HD). METHODS: Using a longitudinal cohort of 314 prevalent HD patients without dementia at baseline, we examined the association of predialysis systolic BP (SBP) and diastolic BP (DBP), pulse pressure, and intradialytic SBP change (pre minus post), averaged for a month, with cognitive decline. Cognitive function was determined by a neurocognitive battery, administered yearly. Individual cognitive test results were reduced into 2 domain scores using principal components analysis (by definition mean of 0 and SD of 1), representing memory and executive function. Joint models, allowing for characterization of cognitive score slopes and including adjustment for potential confounders, were utilized to account for competing risks from death, dropout, or kidney transplantation. RESULTS: Mean age was 62 years; 54% were men, 23% were black, and 90% had at least a high school education. During median follow-up of 2.1 years (25th-75th: 1.0-4.5), 191 had at least one follow-up test, 148 died, and 43 received kidney transplants. Low predialysis DBP and high pulse pressure were both associated with steeper executive function decline (each 10 mm Hg lower DBP = -0.03 SD [-0.01 to -0.05] per year steeper decline) in executive function (each 10 mm Hg higher pulse pressure = -0.03 SD [-0.06 to -0.01] steeper decline) but not for memory function. SBP and intradialytic change were not associated with steeper decline for either memory or executive function. CONCLUSIONS: No relationship was seen between SBP or intradialytic change in BP with cognitive decline. In prevalent HD patients, lower predialysis DBP and wider predialysis pulse pressure are associated with steeper cognitive decline in executive function but not memory.