Symptoms and Association with Health Outcomes in Relapsing-Remitting Multiple Sclerosis: Results of a US Patient Survey

Abstract

Background. A variety of symptoms have been reported, but the prevalence of specific symptoms in relapsing-remitting multiple sclerosis (RRMS), how they are related to one another, and their impact on patient reported outcomes is not well understood. Objective. To describe how symptoms of RRMS cooccur and their impact on patient-reported outcomes. Methods. Individuals who reported a physician diagnosis of RRMS in a large general health survey in the United States indicated the symptoms they experience because of RRMS and completed validated scales, including the work productivity and activity impairment questionnaire and either the SF-12v2 or SF-36v2. Symptom clusters were identified through hierarchical cluster analysis, and the relationship between clusters and outcomes was assessed through regression. Results. Fatigue, difficulty walking, and numbness were the most commonly reported symptoms. Seven symptom clusters were identified, and several were significantly related to patient reported outcomes. Pain, muscle spasms, and stiffness formed a cluster strongly related to physical quality of life; depression was strongly related to mental quality of life and cognitive difficulty was associated with work impairment. Conclusions. Symptoms in RRMS show a strong relationship with quality of life and should be taken into consideration in treatment decisions and evaluation of treatment success.

Figure 1

Dendrogram of symptoms in RRMS. Note: symptoms whose lines intersect towards the left of the figure are more closely related than those whose lines intersect further to the right.

Figure 2

Regression-adjusted decrements in health-related quality of life associated with symptom clusters. Note: bars represent mean adjusted difference between presence of a symptom (clusters 3, 4, and 5) or more numerous symptoms in the cluster (clusters 1, 2, 4, and 7) relative to absence or less numerous symptoms in the cluster, respectively. Cluster labels are presented in Figure 1. SF-6D scores and self-rated health have been rescaled to allow for presentation with MCS and PCS scores. *P < 0.05.