Psychobehavioral predictors of somatoform disorders in patients with suspected allergies

OBJECTIVE: To explore a combination of health-related psychobehavioral features as potential positive criteria for somatoform disorders (SFD). Currently, SFD can only be diagnosed in the absence of sufficient organic symptom explanation, resulting in low criterion validity and delay of appropriate therapy.

METHODS: Cross sectionally, we studied various psychobehavioral characteristics of 197 inpatients with suspected allergies. At the beginning of the medical work-up, patients were interviewed and completed a set of self-rating questionnaires (Illness Perception Questionnaire-Revised, Whiteley Index-7, Cognitions About Body And Health Questionnaire, Scale for the Assessment of Illness Questionnaire, Health Attitude Survey, Reassurance Questionnaire, and Patient Health Questionnaire). Organic explicability of the presenting symptoms was assessed by allergists at the end of the work-up. Forty-eight patients with SFD were compared with 149 patients without SFD, and predictive models were set up. To control for effects of the work-up situation, we also investigated 47 patients with an established diagnosis of hymenoptera venom allergy.

RESULTS: In the work-up group, various self-reported psychobehavioral features discriminated patients with SFD from patients without SFD. In logistic regression analysis, self-reported dissatisfaction with medical care, disease conviction, reduced symptom controllability, and reduced body scanning independently predicted SFD. A predictive model based on these psychobehavioral characteristics had high sensitivity and specificity (area under the curve = 0.86, 95% Confidence Interval = 0.79-0.93; p < .001), which was comparable to the Patient Health Questionnaire-15, an established SFD screening tool assessing somatization.

CONCLUSIONS: Psychobehavioral characteristics in patients with SFD cannot solely be attributed to the uncertainty of a work-up situation. Their predictive value is comparable to that of the traditional measuring of symptom number and severity; hence, they should be considered as SFD positive criteria in Diagnostic and Statistic Manual of Mental Disorders, 5th Edition.