Haemodialysis patients with cognitive impairment are at risk of premature mortality, which does not appear be associated with education, according to data from the COGNITIVE-HD Study.
The study included 676 adult haemodialysis patients (median age, 70.9 years; 38.8 percent female) treated in 20 Italian dialysis clinics. All patients underwent a neuropsychological assessment to determine cognitive function across the following domains: memory, attention, executive function, language and perceptual-motor function.
Of the 664 patients with complete data, 527 (79.4 percent) had cognitive impairment. A total of 206 deaths occurred during a median follow-up of 3.3 years (1,874 person-years).
Nested multivariable Cox regression models showed that patients with any cognitive impairment had a 77-percent higher risk of mortality relative to those without impairment (hazard ratios [HR], 1.77, 95 percent CI, 1.07–2.93). The corresponding HRs associated with one, two and three-to-five domains impaired were 1.48 (0.82–2.68), 1.88 (1.01–3.53) and 2.01 (1.14–3.55).
On the other hand, every standard deviation increase in global cognitive function score was associated with a 32-percent reduction in mortality risk (HR, 0.68, 0.51–0.92).
Compared with patients with primary or lower education, those with lower secondary or upper secondary/higher had HRs for mortality of 0.79 (0.53–1.20) and 1.13 (0.80–1.59), respectively. The cognition-by-education interaction was not significant (p=0.7).
The study was limited by potential selection bias from nonparticipation, lack of data on cognitive decline and the inability to control for other socioeconomic factors.