Depression Serves as a Mediator Between Fatigue and Mental Health-Related QoL in MS

One of the most common symptoms of multiple sclerosis (MS) is fatigue, which has a significant impact on mental health-related quality of life (QoL). A study analyzed how depression and physical activity affect the relationship between fatigue and QoL.

Data from an international cohort of 2,104 patients with MS were evaluated to collect characteristics of fatigue, per the Fatigue Severity Scale, and mental QoL, per the Multiple Sclerosis Quality of Life-54. Structural equation models (SEMs) were used to assess the mediating roles of depression and physical activity between fatigue and mental QoL.

The median mental QoL score, on a 100-point scale, was 71.9. The mean fatigue score, out of 63.0, was 41.5; two-thirds of patients reported clinically significant fatigue. The SEM assessing the mediating properties of depression in the fatigue-mental QoL relationship found that, among patients with clinically significant fatigue, mental QoL was 14.72 points lower (95% confidence interval [CI], –16.43 to –13.01; P<0.001); depression accounted for more than half of this difference (–7.80; 95% CI, –9.03 to –6.57; P<0.001).

The SEM assessing the mediating impact of physical activity in the fatigue-mental QoL relationship found that patients with clinically significant fatigue had mental QoL that was 10.89 points lower (95% CI, –12.47 to –9.32; P<0001), but physical activity constituted less than 5% of this difference (–0.48; 95% CI, –0.81 to –0.14; P=0.005).

“Prospective clinical research could examine how lifestyle (including physical activity) and pharmaceutical treatment of depression in those with poor QoL could impact fatigue, QoL, and their inter-relationship,” the study authors concluded.