Medical and psychiatric determinants of outpatient medical utilization.

Ninety-two general medical outpatients were surveyed with an interview, questionnaires, and a medical record review to investigate the relationships among psychiatric disorder (depression and hypochondriasis), somatic symptoms, medical morbidity, and the utilization of ambulatory medical services. Medical utilization correlated with the number of somatic symptoms reported (r = 0.49, P = 0.0001), depressive symptoms (r = 0.34, P = 0.001), and the number of medical diagnoses in the medical record. Somatic symptoms were not significantly correlated with the number of medical diagnoses, but were related to hypochondriacal attitudes (r = 0.52, P = 0.0001) and depression (r = 0.51, P = 0.0001). In stepwise multiple regressions, the number of medical diagnoses accounted for 33% of the variance in medical utilization. Somatic symptoms were the second most powerful predictor, increasing R2 to 0.469. The next best predictors were two hypochondriacal attitudes and the presence of a major psychiatric diagnosis in the medical record. This five-step model explained 56% of the variance. Somatic symptoms are thus powerful determinants of medical utilization, even after controlling for medical morbidity. Depression, disease fear, and bodily preoccupation are also important predictors of utilization. Somatic symptoms are a final common pathway through which emotional disturbance, psychiatric disorder, and organ pathology all express themselves, and which prompt patients to visit doctors.