Cognition and physical disability in predicting health-related quality of life in multiple sclerosis

Many studies have shown that multiple sclerosis (MS) has a significant impact on patient health-related quality of life (HRQOL), but the relative contributions of physical versus cognitive disability are not well established. Most studies have relied on HRQOL outcomes that depend largely on patient mood, life satisfaction, and personal happiness. The Sickness Impact Profile (SIP) is a measure of HRQOL known for its relatively strong emphasis on task completion and activities of daily living. As such, the SIP may be less influenced by depression. We sought to determine the relative influence of physical disability and cognition, above and beyond demographic and disease variables, in predicting HRQOL. Patients (n = 132) and healthy controls (n = 26) underwent complete neuropsychological evaluation using the Minimal Assessment of Cognitive Function in MS (MACFIMS) battery and a series of self-report measures assessing depression, fatigue, and HRQOL. The SIP was also administered. Correlation analysis and group comparisons revealed significant associations between cognition and HRQOL outcomes. Logistic regression models comparing the Expanded Disability Status Scale (EDSS) and cognitive tests in predicting poor physical HRQOL retained both EDSS and Symbol Digit Modalities Test (SDMT) performance, while models predicting poor psychosocial and poor overall HRQOL retained only the SDMT. These findings support cognition as a significant predictor of overall HRQOL, psychosocial HRQOL, and, interestingly, physical HRQOL.