ObjectiveTo discern population-adjusted rates of office-based physician visits in the US documenting the use of antidepressant pharmacotherapy, a diagnosis of a depressive illness, or a diagnosis of a depressive disorder in concert with the use of antidepressant pharmacotherapy.Materials and MethodsData from the US National Ambulatory Medical Care Survey for the time-period of 1990 through 1998 were used to discern the population-adjusted rate of office-based physician visits documenting the use of antidepressant pharmacotherapy [tricyclic antidepressants (TCAs), selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs) or others], a diagnosis of depression (ICD-9-CM codes 296.2 to 296.36, 300.4 or 311) or both.ResultsOffice-based visits documenting the use of antidepressant pharmacotherapy for any purpose escalated from 16 534 268 in 1990 to 40 925 824 in 1998, a 147.5% increase. The number of office-based visits documenting a diagnosis of depression increased 59.1% during this period, while the proportion of office-based visits documenting a diagnosis of depression and use of antidepressant pharmacotherapy increased 31.3%. Among patients with a diagnosis of depression, use of a TCA declined from 42.1% in 1990 to 9.7% in 1998. In contrast, use of an SSRI increased from 37.1% in 1990 to 65.6% in 1998. The population-adjusted rate of office-based visits documenting the use of antidepressant pharmacotherapy for any purpose increased from 6.7 per 100 US population in 1990 to 15.1 per 100 US population in 1998, a 125.4% increase; documentation of a diagnosis of depression increased from 6.1 per 100 US population in 1990 to 8.9 per 100 US population in 1998, a 45.9% increase; and the recording of a diagnosis of depression in concert with the use of antidepressant pharmacotherapy increased from 3.2 per 100 US population in 1990 to 6.1 per 100 US population in 1998, a 90.6% increase.ConclusionOver the time-period 1990 to 1998, there was a significant increase in the rate of diagnosis of depressive illness in the US, and a sustained preference for use of an SSRI in the treatment of depression.