Are psychological features useful in classifying patients with somatic symptoms?

OBJECTIVE: To evaluate psychological characteristics that could be used for the classification of somatic syndromes requesting medical care. Positive psychological classification criteria are needed to justify the classification of somatic syndromes as Diagnostic and Statistical Manual of Mental Disorders- or International Classification of Diseases-10 section F/mental disorders diagnosis.

METHODS: From a population-based sample of 2510 people, subsamples reporting high scores for somatic symptoms (SOM+; n = 154) versus average scores for somatic symptoms (SOM-; n = 167) were defined. Telephone interviews (e.g., structured interviews for diagnoses, healthcare use, symptom history, possible psychological characteristics), self-rating scales (e.g., Pain Disability Index, depression scale Patient Health Questionnaire-9), and general practitioners reports were collected for these subsamples. In addition to somatic symptoms, we used healthcare use and disability as major external validation criteria.

RESULTS: There was strong evidence for ten of the 28 binary coded psychological variables to identify those people with somatic symptoms who needed medical help and/or were seriously disabled. These variables included "avoidance of physical activities," "bias for somatic illness attributions," "self-concept of being physically weak," and "desperation because of somatic symptoms." The relevance of these psychological characteristics was partially further confirmed by stepwise regression analyses, which showed incremental validity compared with variables like somatic symptoms and depression.

CONCLUSIONS: This study identified several psychological characteristics of people with somatic complaints who need medical care. These features can be assessed, using binary variables that are more feasible for classification processes. These psychological criteria should be included in classification rules for people with somatic syndromes (e.g., somatoform disorders).