Comorbidities Often Accompany Somatoform Disorders

At least 1 out of 6 patients seen by general practitioners in the Netherlands has a somatoform disorder—that is, an illness in which no diagnosable general medical condition can fully account for the physical symptoms— a new Dutch study suggests.

The study was conducted by Ingrid Arnold, M.D., a general practitioner and researcher at Leiden University Medical Center in the Netherlands, and coworkers and was reported in the June British Journal of Psychiatry.

The study was based on a set of questionnaires completed by 1,046 patients seen in eight general medical practices in the Netherlands. Participants completed the SF-36 Functional Limitation Questionnaire as a measure of functional impairment, the Hospital Anxiety and Depression Scale as a measure of anxiety and depression, and the Physical Symptom Checklist to measure the number of reported physical symptoms.

Results from these instruments led to the identification of 506 patients at high risk for a somatoform disorder, 404 (80 percent) of whom participated in a psychiatric diagnostic interview. Of the 540 low-risk patients, 82 were invited for the interview, and 69 (84 percent) participated.

Results from these interviews were used to identify the kind and number of DSM-IV somatoform disorders as well as any anxiety or depressive disorders that the interviewed subjects had.

Of the 404 high-risk subjects interviewed, 116 were found to have a somatoform disorder, 40 an anxiety disorder, and 34 a depressive disorder. Of the 69 low-risk subjects interviewed, three had a somatoform disorder and one an anxiety disorder. The researchers used these data to estimate the prevalence of somatoform disorders as well as the prevalence of anxiety and depression in the entire practice population of 1,046 patients.

The prevalence of DSM-IV somatoform disorders was estimated to be about 16 percent, and the most common somatoform disorder was estimated to be undifferentiated somatoform disorder, with a prevalence of 13 percent. Patients with this disorder suffer from one or more unexplained physical symptoms—such as fatigue, headache, or gastrointestinal symptoms—that cause clinically significant distress or impairment for at least six months.

In contrast, the prevalence of anxiety and depressive disorders was found to be only 4 percent and 6 percent, respectively.

Comorbidity of somatoform disorders and anxiety and depressive disorders, however, appeared to be three times more likely than could have been expected by chance. Of all patients with a somatoform disorder, 26 appeared to also have an anxiety or depressive disorder, and 54 percent of patients with an anxiety or depressive disorder seemed to also have a somatoform disorder.

These results, the researchers concluded, suggest that “somatoform disorders are among the most prevalent psychiatric disorders in general practice.” These results, they also pointed out, imply that there is a high comorbidity of somatoform disorders and anxiety and depressive disorders in general medicine practice.

The results of the study have implications for general practitioners, Arnold told Psychiatric News. “First, 1 in 6 patients who consult their general practitioner suffers from medically unexplained physical symptoms with substantial impairments. This implies that appropriate treatment options should be developed that are effective in primary care.

“Second, half of all patients with anxiety or depression have a comorbid somatoform disorder. Often these physical symptoms are neglected by [general practitioners] since they are considered to be caused by the anxiety or depression... .To engage patients in treatment, we recommend avoiding the counterproductive mind-body dualism that can blame patients and obstruct therapy.”

Regarding the implications of these study results for psychiatrists, Arnold added, studies have shown “that cognitive-behavioral therapy [CBT] is effective for somatoform disorders as well as for depressive or anxiety disorders.” Thus, CBT can help “patients with unexplained physical symptoms irrespective of anxiety or depression,” she said.

The study was funded by the Netherlands Organization for Health Research and Development.

An abstract of the study, “Somatoform Disorders in General Practice,” is posted online at<http://bjp.rcpsych.org/cgi/content/abstract/184/6/470>.▪

The British Journal of Psychiatry 2004 184 470