Cognitive Reserve Is a Determinant of Health-related Quality of Life in Patients With Cirrhosis, Independent of Covert Hepatic Encephalopathy and Model for End-Stage Liver Disease Score

Abstract

Covert hepatic encephalopathy (CHE) is associated with cognitive dysfunction, which affects daily function and health-related quality of life (HRQOL) in patients with cirrhosis. The effects of CHE and liver disease are determined by cognitive reserve—the ability of the brain to cope with increasing damage while continuing to function—and are assessed by composite intelligence quotient (IQ) scores. We examined cognitive reserve as a determinant of HRQOL in patients with cirrhosis. We performed a prospective study of 118 outpatients with cirrhosis without overt HE (age, 56 y). We studied cognition using the standard paper-pencil battery; patients with below-normal results for more than 2 tests were considered to have CHE. We also assessed HRQOL (using the sickness impact profile [SIP]), psychosocial and physical scores (a high score indicates reduced HRQOL), model for end-stage liver disease (MELD) scores, and cognitive reserve (using the Barona Index, a validated IQ analysis, based on age, race, education, residence area, and occupation). Cognitive reserve was divided into average and high groups (<109 or >109), and MELD and SIP scores were compared. We performed regression analyses, using total SIP score and psychosocial and physical dimensions as outcomes, with cognitive reserve, CHE, and MELD score as predictors. Study participants had average MELD scores of 9, and 14 years of education; 81% were white, 63% were urban residents, their mean IQ was 108 ± 8, and 54% had average cognitive reserve (the remaining 46% had high reserves). CHE was diagnosed in 49% of patients. Cognitive reserve was lower in patients with CHE (109) than without (105; P = .02). Cognitive reserve correlated with total SIP and psychosocial score (both r = -0.4; P < .001) and physical score (r = -0.3; P = .01), but not MELD score (P = .8). Patients with high cognitive reserve had a better HRQOL, despite similar MELD scores. In regression analyses, cognitive reserve was a significant predictor of total SIP (P < .001), psychosocial (P < .001), and physical scores (P < .03), independent of CHE, MELD, or psychiatric disorders. A higher cognitive reserve is associated with a better HRQOL in patients with cirrhosis, despite similar disease severity and prevalence. This indicates that patients with good cognitive reserve are better able to withstand the demands of cirrhosis progression and CHE, leading to a better HRQOL. Patients with lower cognitive reserve may need more dedicated and earlier measures to improve HRQOL. Cognitive reserve should be considered when interpreting HRQOL and cognitive tests to evaluate patients with cirrhosis.