Toward the identification of symptom patterns in people with fibromyalgia.

OBJECTIVE: People with fibromyalgia (FM) report a number of physical, cognitive, and psychological symptoms. The purpose of the current study was to determine whether people with FM differed based on the type and severity of symptoms, and if so, whether subgroups differ with respect to health care utilization, functional ability, and work status.
METHODS: Symptom, health care utilization, work, and physical data were available for 2,182 female responders to an Internet survey. Factor analysis was conducted on the physical and cognitive/psychological symptoms, and resulting factor scores were utilized in a cluster analysis to identify subgroups based on symptoms. Cluster groups were compared on a set of variables (e.g., health care utilization, coping).
RESULTS: Factor analyses resulted in 3 symptom factor scores: musculoskeletal, non-musculoskeletal, and cognitive/psychological symptoms. The optimal cluster solution to the cluster analysis revealed 4 clusters. Group 1 was high on all 3 symptom domains, group 2 was moderate on the 2 physical symptom domains and high on cognitive/psychological symptoms, group 3 was moderate on the 2 physical symptom domains and low on cognitive/psychological symptoms, and group 4 was low on all symptom domains. The more symptomatic groups reported the greatest amount of health care utilization and difficulty in coping with symptoms.
CONCLUSION: The FM population is heterogeneous with regard to symptom reporting. Additional research is needed to better understand differential symptom experience among people with FM. Clarification of these differences may increase understanding of the mechanisms involved in FM and provide guidance for treatment decisions.