Contribution of symptom clusters to multiple sclerosis consequences
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PURPOSE: There were two objectives in this study: (1) to identify, among women and men with MS, the extent to which different MS-related symptoms, including fatigue, pain, sleep disturbance, depression, anxiety, irritability, cognitive impairment, spasticity, and poor balance, cluster and (2) to compare the contribution of generated symptom clusters to MS consequences including functional walking capacity, perceived health, illness intrusiveness, and quality of life (QOL). METHODS: This was a cross-sectional study. A center-stratified random sample comprising 139 women and 49 men was recruited from three major MS clinics in Montreal. Subjects completed several self-report and performance-based measures that assessed symptoms and downstream MS consequences. Hierarchical and K-means cluster analyses were used to create clusters. RESULTS: Three symptom clusters were identified. Cluster 1, labeled the "emotional/cognitive symptom cluster," comprised of depression, anxiety, cognitive impairments, and irritability. The second cluster, labeled the "physical symptom cluster," included pain, fatigue, and sleep disorders. Cluster 3, labeled the "motor symptom cluster," included spasticity and poor balance. Furthermore, the motor symptom cluster had a strong effect on functional walking capacity, while it did not affect significantly illness intrusiveness and QOL. On the other hand, the physical symptom clusters and emotional/cognitive symptom clusters showed a significant contribution to prediction of illness intrusiveness and QOL. All symptom clusters showed a significant effect in predicting the overall variability of perceived health status. CONCLUSIONS: The findings of this study provide useful information to help healthcare professionals, clinicians, and researchers to target symptoms that are often in the same cluster when one or two of them are present. Identification of the strength of the contributions of each symptom clusters to the targeted MS consequences would further help to prioritize treatment approaches for the MS population.