ObjectiveThe purpose of this study was to evaluate the use of antidepressants through use of mutually exclusive disease indications using a managed care database.Design and settingA claims database from a 225 000 member managed care organisation was used for the study. A hierarchy of mutually exclusive antidepressant indications was developed: ‘Depression’, ‘Other Approved Indication’, ‘Mental Health’, ‘Surrogate Diagnosis’, ‘Other Uses’, ‘Chronic Disease’, and a residual ‘Unclassified’ hierarchical indication group.Main outcome measures and resultsPatients in the Depression and Other Approved Indication hierarchical groups likely received the antidepressant drugs primarily for these indications and frequently received selective serotonin reuptake inhibitors (SSRIs). Use of antidepressants in the Mental Health Disorders hierarchical group may have been for a related disease. The patients in the Surrogate Diagnosis, Other Uses, Chronic Diseases, and Unclassified hierarchical groups were significantly older than those patients in the Depression group and tricyclic antidepressant (TCA) use was more frequent than the SSRIs. The patients in the Unclassified diagnosis group may represent antidepressant use that is not adequately documented or not indicated. The Surrogate Diagnosis and Chronic Diseases hierarchical groups total healthcare costs were significantly higher than those observed in patients with a Depression diagnosis.ConclusionsUse of mutually exclusive hierarchical diagnosis groups proved to be a useful strategy for assessing antidepressant drug use. SSRI use was more common in the Depression and Other Approved Indication hierarchical groups. Patients in the Surrogate Diagnosis, Other Uses, Chronic Diseases, and Unclassified hierarchical groups used TCAs more frequently.