Comparison of first refill rates among users of sertraline, paroxetine, and citalopram

Background:Research suggests high rates of discontinuation of selective serotonin reuptake inhibitors (SSRIs).Objective:The aim of this study was to compare the rates of first refill for sertraline, paroxetine, and citalopram, the 3 most commonly used SSRIs that were under patent protection at the time of the study. SSRIs that were available in generic formulations in this period were not included in the analysis because prescribing patterns and compliance rates for generic products may differ from those of branded products.Methods:This analysis was conducted using claims data from an administrative database. Claims from January 1, 1999, through June 30, 2002, were analyzed. Adults aged 18 to 64 years with a diagnosis of depression, posttraumatic stress disorder, or social anxiety disorder who had initiated one of the SSRIs of interest during this period were included in the analysis. Refill status was determined based on a refill of the SSRI prescription within 1.5 times the days' supply dispensed or 15 days after the dispensing date of the index SSRI. To adjust for the effects of confounding factors, we conducted a multivariate logistic regression on the status of the first refill. The covariates included age (continuous variable), sex, index durgs (with sertraline as the reference group), and a dummy variable for copayment >$15.Results:Recipients of sertraline (n=5590) or citalopram (n=4124) were more likely than recipients of paroxetine (n=5201) to refill their original prescriptions (refill rate, 54.70%, 54.49%, and 50.99%, respectively; both comparisons, P<0.001). In the logistic regression, the effects of age, sex, and copayment were not significant.Conclusions:This study found that the likelihood of refilling the first prescription varied by SSRI. In the population studied, patients were significantly more likely to refill the first prescription for sertraline or citalopram than the first prescription for paroxetine.