Stability of somatization disorder and somatization symptoms among primary care patients

Background: Diagnostic criteria for somatization disorder emphasize its early onset and long-term stability. Research assessments of somatization disorder depend on lifetime recall of medically unexplained somatic symptoms. Methods: Longitudinal data from the World Health Organization Psychological Problems in General Health Care study were used to examine stability of somatization disorder and somatization symptoms over 12 months. At 15 study sites in 14 countries, consecutive primary care patients (N = 25 916) were screened using the 12-item General Health Questionnaire. A stratified random sample (n = 5447) was selected for a baseline diagnostic assessment using the Composite international Diagnostic Interview. All cases and a random sample of noncases were asked to complete a follow-up diagnostic assessment 12 months later (n = 3196). Results: While the baseline and 12-month interviews identified a similar number of patients with DSM-IV somatization disorder (74 and 70), only 21 cases were consistently identified at both assessments. Examination of individual symptoms found that 61% of lifetime medically unexplained somatic symptoms detected at baseline were not detected during the lifetime interview 12 months later. When analyses were broadened to all lifetime symptoms reported at baseline (including those found to be "medically explained" or "not clinically significant"), 43% of lifetime symptoms reported at baseline were "lost'' 12 months later. Conclusions: Given that the baseline and follow-up assessments both asked about lifetime symptoms, the loss of somatization disorder or individual somatic symptoms can only represent inconsistent recall. The instability of recall observed here has significant implications for the diagnosis of somatization disorder by structured interview and may also have implications for current diagnostic criteria.