Objectives: Investigators and clinicians almost always rely on Diagnostic and Statistical Manual of Mental Disorder, 4th edition's (DSM-IV) somatoform disorders (and its derivative diagnoses) to characterize and identify patients with medically unexplained symptoms (MUS). Our objective was to evaluate this use by determining the prevalence of DSM-IV somatoform and nonsomatoform disorders in patients with MUS proven by a gold standard chart review.
Methods: In a community-based staff model HMO, we identified subjects for a clinical trial using a systematic and reliable chart rating procedure among high-utilizing MUS patients. Only baseline data are reported here. The World Health Organization Composite International Diagnostic Interview provided full and abridged DSM-IV diagnoses. Patients with full or abridged DSM-IV somatoform diagnoses were labeled "DSM somatoform-positive," whereas those without them were labeled "DSM somatoform-negative."
Results: Two hundred six MUS patients averaged 13.6 visits in the year preceding study, 79.1% were females, and the average age was 47.7 years. We found that 124 patients (60.2%) had a nonsomatoform ("psychiatric") DSM-IV diagnosis of any type; 36 (17.5%) had 2 full nonsomatoform diagnoses, and 41 (19.9%) had >2; 92 (44.7%) had some full anxiety diagnosis and 94 (45.6%) had either full depression or minor depression diagnoses. However, only 9 of 206 (4.4%) had any full DSM-IV somatoform diagnosis, and only 39 (18.9%) had abridged somatization disorder. Thus, 48 (23.3%) were "DSM somatoform-positive" and 158 (76.7%) were "DSM somatoform-negative." The latter exhibited less anxiety, depression, mental dysfunction, and psychosomatic symptoms (all p <.001) and less physical dysfunction (p = .011). Correlates of this DSM somatoform-negative status were female gender (p = .007), less severe mental (p = .007), and physical dysfunction (p = .004), a decreased proportion of MUS (p <.10), and less psychiatric comorbidity (p <.10); c-statistic = 0.77.
Conclusion: We concluded that depression and anxiety characterized MUS patients better than the somatoform disorders. Our data suggested radically revising the somatoform disorders for DSM-V by incorporating a new, very large group of now-overlooked DSM somatoform-negative patients who were typically women with less severe dysfunction.