PAIN, DISABILITY, AND PHYSICAL FUNCTIONING IN SUBGROUPS OF PATIENTS WITH FIBROMYALGIA

Objective. To investigate (1) whether patients with fibromyalgia (FM) could be subgrouped on the basis of psychosocial and behavioral respon ses to pain, and (2) the relationships among pain severity, perceived disability, and observed physical functioning, as measured by cervical spinal mobility. Methods. 117 patients with FM received a comprehensi ve examination, underwent physical performance tasks during the evalua tion, and completed self-report inventories. Results. About 87% of the patients could be classified into the Multidimensional Pain Inventory clustering groups identified and validated in patients with a range o f chronic pain problems (Dysfunctional, Interpersonally Distressed, an d Adaptive Copers). Although the 3 groups exhibited comparable levels of physical functioning, the Dysfunctional and Interpersonally Distres sed patients reported higher levels of pain; disability, and depressio n. Interpersonally Distressed patients also reported significantly low er levels of marital satisfaction than the other 2 subgroups. There we re significant associations between pain severity and perceived disabi lity, and pain severity and physical functioning, defined by spinal mo bility tests. The relationship between disability and physical functio ning did not reach statistical significance. Correlational analyses by subgroups revealed a significant association between patient perceive d disability and physical functioning in the Adaptive Copers, but not the Dysfunctional or Interpersonally Distressed patients. Conclusions. Patients with FM can be classified into 3 subgroups based on psychoso cial and behavioral characteristics. These subgroups show substantial differences in clinical presentation of their symptoms. Although the r esults should be considered preliminary due to the narrow range of phy sical functioning, the differential relationships between perceived di sability and physical functioning across cluster groups suggest the im portance of FM syndrome as a heterogeneous disorder. Treating patients with FM as a homogeneous group may compromise research results, imped e understanding of the mechanisms underlying this condition, and deter development of effective treatment.