P atients with medically unexplained symptoms (MUS), also called somatization, have physical symptoms with little or no disease basis. 1 When disease exists, the symptoms are inconsistent with or out of proportion to the disease. 2 Of importance, people with MUS are not necessarily abnormal. Many exhibit it but seldom or never seek care. 3 MUS becomes a medical problem when it leads to frequent health care-seeking for feared but nonexistent physical disease. 4 In this issue of Medical Care, Barsky and colleagues 5 productively focus on unique health care-utilization patterns as a way to identify the most clinically significant MUS patients.The MUS problem is very common and costly. Defined by The Diagnostic and Statistical Manual of Mental Disorders (DSM) 6 and by its abridged and derivative forms, community surveys show a very high prevalence rate, eg, abridged somatization disorder ranges from 4.4% to 22%. 7-10 The prevalence of all types of MUS in the outpatient setting is reported from 25% to 75%. 11-13 Thus, on average, approximately one-half of all outpatients have little or no physical disease explanation for their symptoms. Barsky et al demonstrated that the greater the somatization and utilization, the greater the cost, 5 which they estimated previously at $256 billion per year. 14 Clinically significant MUS, however, is even more prevalent than estimated by DSM-IV: more than three quarters of 206 MUS patients lacked a full or abridged DSM-IV somatoform diagnosis, although they had high levels of depression/anxiety and averaged 13.6 visits per year. 15 The gold standard definition of MUS came from a medical chart rating procedure conducted by trained, reliable physician raters. 16 Because researchers have relied almost entirely on DSM to identify MUS, these large numbers of "DSMnegative" patients have been completely overlooked by the field. 16 Little is known about their clinical features and prognosis.An even greater problem exists. Primary care providers (PCPs) rarely recognize MUS and, therefore, its frequent comorbid psychiatric disorders also are not diagnosed. Approximately two thirds of psychiatric problems in primary care present exclusively with MUS. 17,18 Bridges and Goldberg, 19 Katon et al,20 Kroenke et al, 21 and Kirmayer et al 22 posit that, by falsely suggesting physical/organic diseases, the somatic focus of MUS misleads physicians and contributes to their very low rates of identification of MUS and its comorbid psychiatric diseases. 13,23 For example, misdiagnosis in outpatients with depression varies from 50% to 75% and is as great as 96% in medical inpatients. 23 We have reviewed that treatment in primary care and specialty settings is effective. 24,25 However, patients exhibiting MUS first must be identified to benefit from treatment. Given the difficulties of PCPs in making the diagnosis, a good case can be made for developing MUS screeners that do not involve PCPs.Several current screeners use questionnaires or interviews of patients, but poor recall of chronic symptoms has led to ...