Cognitive function is a major determinant of income among multiple sclerosis patients in Sweden acting independently from physical disability

Background: In multiple sclerosis (MS), various aspects of cognitive function can be detrimentally affected, thus patients' employment and social functioning is commonly impacted. Objective: To analyse income among MS patients in relation to cognitive function, assessed with the Symbol Digit Modalities Test (SDMT). Methods: A cross-sectional study including 2080 MS patients was conducted linking national register-based data. Descriptive statistics and a two-part model were used to estimate differences in earnings and social benefits. Results: MS patients in the highest SDMT score quartile earned more than twice annually compared to patients in the lowest quartile, whereas patients in the lowest quartile received three times more income through social benefits. The difference in earnings and benefits across the SDMT performance quartiles remained statistically significant after adjusting for various clinical and socio-demographic variables, including physical disability. The corrected prevalence ratios for MS patients in the highest quartile for having income from earnings and benefits were 1.40 (95% confidence interval (CI): 1.29-1.49) and 0.81 (95% CI: 0.71-0.90), respectively, when compared to the patients in the lowest quartile. Conclusion: Cognitive function affects the financial situation of MS patients negatively and independently of physical disability. This warrants cognitive testing as a routine measure in health care services for MS patients.