Use of a second generation antipsychotic among patients diagnosed with major depressive disorder in the United States: Prescribing pattern and influence of physician specialty

Purpose: The purpose of the study was to discern the extent of the prescribing of a second generation atypical antipsychotic (SGA), either alone or in combination with an antidepressant, among patients diagnosed with major depressive disorder (MDD) in the US, and the influence of physician specialty on prescribing in 2007. Methods: Data from the 2007 US National Ambulatory Medical Care Survey (NAMCS) were extracted for (i) office-based physician-patient encounters (office-based visits; OBV) with an International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code for MDD (296.2-296.36, 300.4, 311), and without an ICD-9-CM code(s) for co-morbid mental illness; and (ii) OBV with a diagnosis of MDD marked on the 'diagnostic clinical checklist' (DCC) of the NAMCS, and without an ICD-9-CM code(s) for comorbid mental illness. Rates were calculated per 1000 OBV and per 1000 US population as of 1 July 2007. Statistical analyses were conducted using the Statistical Analysis System (SAS®; Cary, NC, USA) version 9.1.3. The quantitative methods employed addressed the complex survey sampling design of the US NAMCS. Descriptive statistics and logistic regression derived odds ratios (ORs) and 95% confidence intervals (CIs) are reported, as are rates per 1000 OBV and per 1000 US population. Results: In 2007, there were (i) 28 457 078 OBVs with an ICD-9-CM code for MDD without co-morbid mental illness. Of these, 20 090 702 (70.6%) reported the prescribing of an antidepressant, 2 420 885 (8.5%) OBVs reported the prescribing of an SGA (7.4% continued, 1.1% new) and 1 981 968 (7.0%) OBVs reported the prescribing of both an antidepressant and an SGA. The probability of prescribing an SGA increased when the physician specialty was psychiatry (OR 10.97; 95% CI 5.57, 21.58); and (ii) 74 561367 OBVs with MDD marked on the DCC without co-morbidmental illness, 37 470 406 (50.3%) OBVs reported the prescribing of an antidepressant, 3 877 385 (5.2%) reported the prescribing of an SGA (4.5% continued, 0.8% new) and 2 785 941 (3.7%) reported the prescribing of both an antidepressant and an SGA. The probability of prescribing an SGA increased when the physician specialty was psychiatry (OR 10.63; 95% CI 6.68, 16.93). The rate of prescribing of both an antidepressant and an SGA was 2.2 per 1000 when the OBV had an ICD-9-CM code for MDD and 3.1 per 1000 when the OBV had MDD marked on the DCC. Conclusions: In 2007, for OBVs with either an ICD-9-CM code for MDD or MDD marked on the DCC, there was modest use of an SGA, and the probability of the prescribing of an SGA increased when the specialty of the physician was psychiatry.