Two healthy lifestyle scores are associated with lower subsequent fatigue risk using inverse probability weighting in an international longitudinal cohort of people with multiple sclerosis

Background and purpose: Several modifiable lifestyle factors have been associated with the onset and health outcomes of multiple sclerosis (MS), including clinically significant fatigue. A combined lifestyle score approach represents one method of assessing their relationship with clinical outcomes. The aim was to examine the association of two lifestyle scores with clinically significant fatigue and change thereof over 2.5 years' follow-up using inverse probability treatment weighting (IPTW).

Methods: Data on sociodemographic, lifestyle, and clinical characteristics surveyed from an international cohort of people with MS at baseline and at 2.5-year follow-up were used. Fatigue was defined by the Fatigue Severity Scale (FSS >5) and healthy lifestyle by the Healthy Lifestyle Index Score (HLIS) and the Smoking, Nutrition, Alcohol Consumption and Physical Activity (SNAP) score. Analyses were by IPTW accounting for age, sex, MS type, disability, treated comorbidity number, immunomodulatory medication use, prescription antifatigue medication use, and ongoing relapse symptoms.

Results: In total, 1268 participants completed the FSS at both time points; approximately 62% had fatigue. Using doubly robust IPTW, high (>11/20) HLIS (odds ratio [OR] 0.90, 95% confidence interval [CI] 0.81-0.98) and high (>3/5) SNAP (OR 0.82, 95% CI 0.73-0.90) were each associated with lower risk of fatigue at follow-up. Evaluating change in fatigue, a higher SNAP score was associated with a lower risk of fatigue (OR 0.89, 95% CI 0.80-0.97) but the score for HLIS did not reach statistical significance (OR 0.93, 95% CI 0.85-1.01).

Conclusion: These results suggest a robust role for key lifestyle factors in preventing clinically significant fatigue and may represent a place for lifestyle modification in improving clinical outcomes in MS.