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.
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.”
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.
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.
HMO = health maintenance organization DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, 4th edition DSM-V = planned for approximately 2010, the Diagnostic and Statistical Manual of Mental Disorders, 5th edition MUS = medically unexplained symptoms ECA = epidemiologic catchment area SD = somatization disorder SF-36 = Short-Form 36 MCS = Mental Component Summary of the SF-36 PCS = Physical Component Summary of the SF-36 SSAS = Spielberger State Anxiety Scale CES-D = Center for Epidemiological Studies Depression inventory PSC = Psychosomatic Symptom Checklist WHO-CIDI = World Health Organization Composite International Diagnostic Interview.
From the Departments of Medicine (R.C.S., J.S.L., A.H., F.C.D.), Psychiatry (R.C.S.), Epidemiology (J.C.G., C.S.), and Family Practice (C.W.G.), the College of Human Medicine, the College of Nursing (C.C., C.L., B.G.), and the Department of Economics (J.G.), Michigan State University, East Lansing, Michigan.
Address correspondence and reprint requests to Robert C. Smith, MD, ScM, B312 Clinical Center, East Lansing, MI 48824. E-mail: Robert.Smith@ht.msu.edu.
Received for publication May 18, 2004; revision received July 30, 2004.
This research was supported by NIMH grant MH57099.