Somatoform disorders are an important determinant of medical care utilization, but their independent effect on utilization is difficult to determine because somatizing patients frequently have psychiatric and medical comorbidity. To assess the extent of the overlap of somatization with other psychiatric disorders; to compare the medical utilization of somatizing and nonsomatizing patients; and to determine the independent contribution of somatization alone to utilization. Patients were surveyed with self-report questionnaires assessing somatization and psychiatric disorder. Medical care utilization was obtained from automated encounter data for the year preceding the index visit. Medical morbidity was indexed with a computerized medical record audit. Two hospital-affiliated primary care practices. Consecutive adults making scheduled visits to their primary care physicians on randomly chosen days. In all, 2668 questionnaires were distributed, and 1914 (71.7%) were returned. Of these, 1546 (80.8%) contained complete data and met eligibility criteria. Medical care utilization and costs within our hospital system in the preceding 12 months. Two hundred ninety-nine patients (20.5%) received a provisional diagnosis of somatization; 42.3% of these patients had no comorbid depressive or anxiety disorder. Somatizing patients, when compared with nonsomatizing patients, had more primary care visits (mean [SE], 4.90 [0.32] vs 3.43 [0.11]; P<.001); more specialty visits (mean [SE], 8.13 [0.55] vs 4.90 [0.21]; P<.001); more emergency department visits (mean [SE], 1.29 [0.15] vs 0.52 [0.036]; P<.001); more hospital admissions (mean [SE], 0.32 [0.051] vs 0.13 [0.014]; P<.001); higher inpatient costs (mean [SE], USD 3146 [USD 380] vs USD 991 [USD 193]; P<.001); and higher outpatient costs (mean [SE], USD 3208 [USD 180] vs USD 1771 [USD 91]; P<.001). When these results were adjusted for the presence of comorbid anxiety and depressive disorders, major medical morbidity, and sociodemographic characteristics, patients with somatoform disorder still had more primary care visits (P = .04), more specialist visits (P = .002), more emergency department visits (P<.001), more hospital admissions (P<.001), more ambulatory procedures (P<.001), higher inpatient costs (P<.001), and higher outpatient costs (P<.001). When these findings are extrapolated to the national level, an estimated USD 256 billion a year in medical care costs are attributable to the incremental effect of somatization alone. Patients with somatization had approximately twice the outpatient and inpatient medical care utilization and twice the annual medical care costs of nonsomatizing patients. Adjusting the findings for the presence of psychiatric and medical comorbidity had relatively little effect on this association.
