Course of antidepressant treatment drug type, and prescriber's specialty

The study examined whether the relationship between the course of antidepressant treatment and the type of prescriber-psychiatrist or nonpsychiatrist-varied by whether a tricyclic antidepressant or a selective serotonin reuptake inhibitor (SSRI) was prescribed.

Pharmacy claims from a nationwide database were analyzed retrospectively. A total of 3,101 adults who did not have a prescription for antidepressants for nine months and who were then given a prescription for a tricyclic or an SSRI antidepressant were followed for 13 to 16 months after the initial prescription. Outcome measures were rates of treatment termination before one month and subtherapeutic dosing, defined as having received no prescribed daily dosages at or above commonly cited thresholds.

Among tricyclic-treated patients, psychiatrists' patients were significantly more likely than nonpsychiatrists' patients to continue in treatment for more than one month (72 percent versus 62 percent). Among patients taking tricyclics for at least three months, those with at least one prescription from a psychiatrist had a significantly higher rate of therapeutic dosing than those with all prescriptions from a nonpsychiatrist (70 percent versus 25 percent). For SSRI-treated patients, rates of termination and therapeutic dosing did not differ significantly by prescriber type. In multivariate equations that controlled for selected differences, effects of drug type and prescriber type were independent when persistence in treatment was analyzed, and interactive when subtherapeutic dosing was analyzed.

Policy making about antidepressant pharmacotherapy should include assessments of the relationships between drug selection and patient outcome across a variety of clinical settings.