(343) - Longitudinal stability of fibromyalgia symptom clusters

Abstract

Using self-report questionnaires of key fibromyalgia symptoms domains (fatigue, sleep disturbance, pain, function, stiffness, dyscognition, depression, and anxiety) we previously identified four unique symptom clusters. The purpose of this study was to examine the stability of fibromyalgia symptom clusters between baseline and two years follow-up. Female patients with a diagnosis of fibromyalgia completed a baseline Brief Pain Inventory, the 30-item Profile of Mood States, the Medical Outcomes Sleep Scale, the Multidimensional Fatigue Inventory, the Multiple Ability Self-Report Questionnaire, the Fibromyalgia Impact Questionnaire-Revised, and the Medical Outcomes Short Form-36. Follow-up measures were completed approximately 2 years later. The hierarchical agglomerative clustering algorithm previously developed was applied; agreement between baseline and follow-up was assessed with the kappa statistic. Among the 433 participants, the mean age was 56 (range 20–85) years. The median FIQ total score was 57 (range: 8–96). 58% (251/433) participants remained in the same cluster at follow-up as compared to baseline, which represented moderate agreement between baseline and follow-up (kappa .44, 95% CI: .37–.50). Only 2 patients changed from high symptom intensity to low symptom intensity; similarly, only 3 moved from low to high. FM patients classified into four unique symptom clusters based on the key domains of fatigue, sleep disturbance, pain, function, stiffness, dyscognition, depression, and anxiety showed moderate stability in cluster assignment at two years of follow-up. Few patients moved between the two extremes of severity, and it was slightly more common to move to a lower symptom level than to worsen.