Objectives: (1) Evaluate the impact of the patient characteristics of disability, gender and employment status on health-related quality of life (HRQOL) in multiple sclerosis (MS) and (2) Characterize the functional relationship between HRQOL and disability overall, and by gender and employment status.
Methods: We assessed the HRQOL of 215 MS outpatients in our clinic using the MSQOL-54 and Fatigue Severity Scale (FSS), and that of 172 healthy controls, using the SF-36 (a subset of MSQOL-54). We compared QOL between MS subgroups defined by disability, gender and employment, and computed the linear and non-linear relationships between disability level measured by the Expanded Disability Status Scale (EDSS) and MSQOL-54 dimensions.
Results: QOL of MS patients measured by SF-36 is lower than controls, varying by QOL dimension with the greatest difference emerging for physical aspects of the disease. The relationship of physical disability, measured by EDSS, and all 14 MSQOL-54 dimensions and FSS is negative; for 12 of the 14 dimensions and FSS it is also non-linear. Non-linearity is most pronounced among women, who show a weak EDSS/QOL relationship at higher levels of physical disability, suggesting women better able to "psychologically buffer" the debilitating aspects of MS. While employed have higher QOL than unemployed, the former are more affected by physical disability.
Conclusions: Multiple attributes, including disability, gender and employment status, affect QOL. QOL's relationship with disability is complex, displaying non-linearity and interacting with patient characteristics. This has implication for QOL research methodology and provides insight into factors affecting patients' perceptions of well-being.