Antidepressant adherence and medical resource use among managed care patients with anxiety disorders.

Objectives: This study evaluated adherence with selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) among patients who newly initiated therapy for anxiety with or without comorbid depression; the study also quantified the health-related economic consequences of nonadherence.
Methods: A large managed care database was used to gather retrospective data for patients with anxiety disorders who had a prescription for an antidepressant between July 1, 2001, and December 31, 2002. The relationship between antidepressant adherence and medical resource utilization was assessed; the analysis controlled for age, gender, utilization of mental health specialty care, change in medication, whether the dosage was titrated, costs in the six months before the prescription for an antidepressant, and comorbid physical conditions.
Results: Of the 13,085 patients with anxiety diagnoses who met the criteria for study inclusion, 57 percent were nonadherent to antidepressant therapy at six months. Patients who received mental health specialty care were more likely than those who did not receive such care to be adherent to therapy (48.5 percent compared with 40.7 percent; p<.001). Those with dual diagnoses of anxiety and depression were more likely than those with anxiety alone to be adherent to therapy (46.8 percent compared with 40.2 percent; p<.001). Those with a coded diagnosis of posttraumatic stress disorder had the highest medical costs. Patients with anxiety and depression had significantly higher total costs than patients with anxiety alone. Adherent patients who did not have a change in medication or a titrated dosage had significantly lower medical costs than nonadherent patients; however, total costs (medical plus pharmacy) were similar.
Conclusions: Nonadherence with antidepressant therapy in anxiety disorders is common, but mental health specialty care may be associated with improved adherence. Lower medical costs for adherent patients who did not have a change in medication or a titrated dosage offset the increase in pharmacy costs, resulting in total costs (medical plus pharmacy) that were similar to those of nonadherent patients.