Features of somatization predict the onset of chronic widespread pain: results of a large population-based study.

OBJECTIVE: Chronic widespread pain, the clinical hallmark of the fibromyalgia syndrome, is associated with other physical and psychological symptoms both in patients studied in a clinical setting and in those identified in the community. The present study was undertaken to examine the hypothesis that psychological and physical indicators of the process of somatization predict the development of new chronic widespread pain.
METHODS: In this population-based prospective study, 1,658 adults ages 18-65 years completed a detailed pain questionnaire, which included a pain drawing. They also completed the following psychosocial instruments: General Health Questionnaire, Somatic Symptom Checklist, Fatigue Questionnaire, and Illness Attitude Scales. Individuals were followed up at 12 months, at which time 1,480 (93% of subjects still living at their baseline address) provided data on pain status, using the same instruments.
RESULTS: At baseline, 825 subjects were classified as pain free and 833 as having pain not satisfying criteria for chronic widespread pain. Of those, 18 (2%) and 63 (8%), respectively, were classified as having chronic widespread pain at followup. After adjustment for age and sex, there were strong relationships between baseline test scores and subsequent risk of chronic widespread pain (odds ratio for the Somatic Symptom Checklist 3.3; odds ratio for the Illness Behavior subscale of the Illness Attitude Scales 9.0). All 95% confidence intervals excluded unity. These associations were independent of baseline pain status.
CONCLUSION: Subjects who are free of chronic widespread pain are at increased future risk of its development if they display other aspects of the process of somatization. Data from this population-based prospective study lend powerful support to the hypothesis that chronic widespread pain can be one manifestation of the somatization of distress.