About one-half of all patients beginning a new course of pharmacotherapy for GAD receive either an SSRI or venlafaxine. The typical duration of therapy with these agents was only about three months; almost one-half of patients who began treatment with an SSRI or venlafaxine, however, had evidence of continuing receipt of medication at one year. Benzodiazepines, which about one-third of study subjects received as initial therapy, were administered--not unexpectedly--for a shorter period time, and mean duration of therapy was about one month.
About one in five patients beginning treatment with a benzodiazepine had evidence of continuing receipt beyond 90 days. Lacking information on disease severity, we could not assess the appropriateness of such long-term use. To the extent these patients had symptoms refractory to other medications, long-term treatment with benzodiazepines may have been appropriate, notwithstanding well-known risks associated with such therapy (e.g., dependence, cognitive impairment, increased risk of falls, risk of rebound anxiety) when treatment is discontinued [11
Mean total healthcare costs were $2370 higher during the one-year period of follow-up than in the one-year period preceding treatment. While we do not know the exact reason(s) for this difference, we suspect that it may be related to GAD-related care (GAD-related pharmacotherapy comprised 18% of this increase), exacerbation of pre-existing comorbidities or decreased ability to cope with these conditions, and/or new somatic manifestations of GAD (e.g., chest pain, gastrointestinal disorders). Further research is needed to better understand this phenomenon.
The increase in costs (follow-up vs pretreatment) that we observed is substantially greater than that reported by Francois and colleagues ($1340). We suspect that the principal reason for this difference is that our study only included patients initiating pharmacotherapy for GAD, while only 44% of the patients in the Francois study received an antidepressant or anxiolytic anytime during follow-up [16
]. Presumably, patients initiating pharmacotherapy for GAD will have more severe illness--and incur greater costs--than patients newly diagnosed with GAD who do not receive drug therapy.
An important limitation of our study was the omission of fluoxetine from the group of SSRIs. We excluded fluoxetine because it is not indicated for the treatment of GAD, and has not been studied extensively in this indication. Nonetheless, there is evidence that it may be prescribed for this disorder [20
]. In one recent study of 305 patients with GAD and 232 with social phobia, it was reported to be the most commonly prescribed SSRI [18
] (benzodiazepines were the most commonly used medications in both indications). Our exclusion of fluoxetine undoubtedly resulted in our underestimating the number of GAD patients beginning therapy with an SSRI. We note, however, that although fluoxetine was not on our list of designated GAD-related medications, patients who received it during the one-year pretreatment period were excluded from our study sample (as were those who received any other SSRI, any SNRI, or any benzodiazepine during pretreatment). Thus, patients could not have been included in our study population if they were adding a second agent (e.g., a benzodiazepine) to fluoxetine or switching from fluoxetine to another agent.
There are several other important limitations of our study. First, as with all claims database studies, there may be errors of omission and commission in coding. Accordingly, some patients with GAD may not have been included in our study sample due to absence of appropriate diagnoses on healthcare claims, while others who received a diagnosis of GAD incorrectly and therefore should have been excluded were not. As patient medical records were not available to us, the degree to which patients were actually misclassified is unknown. Also, the database does not contain important clinical information on disease severity. Without such information, it is difficult to assess the appropriateness of the therapeutic patterns that we observed.