What factors influence the prescribing of antidepressant pharmacotherapy? An assessment of national office-based encounters

Objective: This study was designed to identify: 1) predictors of antidepressant pharmacotherapy among patients diagnosed with depression; and 2) predictors of prescription for either a selective-serotonin reuptake inhibitor (SSRI), or a serotonin-norepinephrine reuptake inhibitor (SNRI). Method: Data from the 1995 National Ambulatory Medical Care Survey (NAMCS) were used to discern the number of office-based encounters documenting a diagnosis of depression (ICD-9-CM codes 296.2-296.36; 300.4; or 311) among patients eighteen years of age or older. Logistic regression-derived odds ratios (OR) and 95 percent confidence intervals (CI) were used to elucidate factors predictive of receipt of antidepressant pharmacotherapy, and, more specifically, factors predictive of receipt of an SSRI or an SNRI, Model variables included age (18-49 years as compared to greater than or equal to 50 years); race (white as compared to nonwhite, inclusive of Hispanics); gender; self-report of depression as a reason for the office-based encounter, and payer type (private insurance program as compared to public). Results: Among the estimated 18,046,293 office-based visits resulting in a diagnosis of depression, 56.2 percent of patients self-reported depression as a reason for the office based encounter; 67.5 percent were prescribed or continued a regimen of antidepressant pharmacotherapy; and 48.3 percent were prescribed an SSRI or an SNRI, Factors predictive of receipt of antidepressant pharmacotherapy included age less than fifty years (OR = 1.30, CI = 1.01-1.67); female gender (OR = 1.45, CI = 1.13-1.85); and self-report of depression as a reason for the office-based encounter (OR = 1.98, CI = 1.57-2.51). Factors predictive of receipt of an SSRI or an SNRI included age less than fifty years (OR = 1.31, CI = 1.03-1.65); female gender (OR = 1.55, CI = 1.23-1.95); and self-report of depression as a reason for the office-based encounter (OR = 1.56, CI = 1.25-1.95). In addition, having private insurance increased the likelihood of having been prescribed an SSRI or SNRI by 46 percent (OR = 1.46, CI = 1.13-1.89). Conclusions: Among patients with a diagnosis of depression, the pattern of prescribing antidepressant pharmacotherapy is influenced by a patient's age, gender, self-report of depression, and type of insurance coverage. Further research is required to discern the reasons for these observed effects and to advance clinically rational and equitable access to pharmacotherapeutic innovation.