Pregabalin versus SSRIs and SNRIs in benzodiazepine-refractory outpatients with generalized anxiety disorder: a post hoc cost-effectiveness analysis in usual medical practice in Spain

Marina De Salas-Cansado,¹ José M Olivares,² Enrique Álvarez,³ Jose L Carrasco,⁴ Andoni Barrueta,⁵ Javier Rejas,<sup>5

1</sup>Trial Form Support Spain, Madrid; ²Department of Psychiatry, Hospital Meixoeiro, Complejo Hospitalario Universitario, Vigo; ³Department of Psychiatry, Hospital de la Santa Creu i San Pau, Barcelona; ⁴Department of Psychiatry, Hospital Clínico San Carlos, Madrid; ⁵Health Outcomes Research Department, Medical Unit, Pfizer Spain, Alcobendas, Madrid, Spain

Background: Generalized anxiety disorder (GAD) is a prevalent health condition which seriously affects both patient quality of life and the National Health System. The aim of this research was to carry out a post hoc cost-effectiveness analysis of the effect of pregabalin versus selective serotonin reuptake inhibitors (SSRIs)/serotonin norepinephrine reuptake inhibitors (SNRIs) in treated benzodiazepine-refractory outpatients with GAD.
Methods: This post hoc cost-effectiveness analysis used secondary data extracted from the 6-month cohort, prospective, noninterventional ADAN study, which was conducted to ascertain the cost of illness in GAD subjects diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria. Benzodiazepine-refractory subjects were those who claimed persistent symptoms of anxiety and showed a suboptimal response (Hamilton Anxiety Rating Scale ≥16) to benzodiazepines, alone or in combination, over 6 months. Patients could switch to pregabalin (as monotherapy or addon) or to an SSRI or SNRI, alone or in combination. Effectiveness was expressed as quality-adjusted life years gained, and the perspective was that of the National Health System in the year 2008. A sensitivity analysis was performed using bootstrapping techniques (10,000 resamples were obtained) in order to obtain a cost-effectiveness plane and a corresponding acceptability curve.
Results: A total of 282 subjects (mean Hamilton Anxiety Rating Scale score 25.8) were identified, comprising 157 in a pregabalin group and 125 in an SSRI/SNRI group. Compared with SSRI/SNRI, pregabalin (average dose 163 mg/day) was associated with higher quality-adjusted life years gained (0.1086 ± 0.0953 versus 0.0967 ± 0.1003, P = 0.334), but increased health care costs (€1014 ± 762 versus €846 ± 620, P = 0.166) and drug costs (€376 ± 252 versus 220 ± 140, P < 0.001), resulting in an incremental cost-effectiveness ratio of €25,304 (95% confidence interval dominant 149,430) per quality-adjusted life years gained for health care costs and €25,454 (dominant 124,562) when drug costs were considered alone. Eighty-six percent of resamples fell below the threshold of €30,000 per quality-adjusted life years.
Conclusion: This evaluation suggests that pregabalin may be cost-effective in comparison with SSRIs/SNRIs in benzodiazepine-refractory outpatients with GAD treated in mental health care settings under usual medical practice in Spain.

Keywords: cost-effectiveness, generalized anxiety disorder, benzodiazepine-refractory patients, pregabalin, quality-adjusted life years