Modelling the cost-effectiveness of pregabalin versus usual care in daily practice in the treatment of refractory generalised anxiety disorder in Spain

Abstract

To model the cost-effectiveness (CEA) of the use of pregabalin versus usual care (UC) in outpatients with refractory generalised anxiety disorder (GAD) treated in daily practice in mental health settings in Spain. This CEA model used data extracted from a 6-month prospective non-interventional trial: the Amplification of Definition of ANxiety (ADAN) study, which was conducted to determine the cost-of-illness in GAD subjects. Refractory subjects were those who reported persistent symptoms of anxiety and showed suboptimal response in the Hamilton-anxiety scale (HAM-A≥16) after a standard dose regimen of anxiolytics other than pregabalin, alone or in combination, over 6months. The pregabalin arm was documented with data extracted from patients who received pregabalin in the study for the first time, added or replacing the existing therapy. In the UC arm, treatment might include one or more of the following: a serotonin selective reuptake inhibitor, a serotonin-norepinephrine reuptake inhibitor, other anti-depressants, a benzodiazepine or an anti-epileptic drug other than pregabalin. The time horizon of the modelling was 6months in the base-case scenario, and the National Health System perspective was chosen to calculate costs. Effectiveness was expressed as quality-adjusted life years (QALYs) gained, which were derived using the EQ-5D questionnaire, at baseline and end-of-trial visits. Results of the CEA model was expressed as an incremental cost-effectiveness ratio (ICER) per QALY gained. Probabilistic sensitivity analysis using bootstrapping techniques was also carried out to obtain the cost-effectiveness plane and the corresponding acceptability curve. Data from a total of 429 subjects per arm (mean HAM-A score 25.7) meeting eligible criteria for inclusion in CEA modelling were extracted from the original trial. Compared with UC, pregabalin (average dose 218mg/day) was associated with significantly higher QALY gain; 0.1209±0.1030 versus 0.0994±0.0979 (P=0.003), but increased healthcare costs as well; <euro>1,272±1,240 versus <euro>1,070±1,177 (P<0.069) and drug costs <euro>525±252 versus 219±211 (P<0.001), resulting in an ICER of <euro>15,804/QALY (95% CI 6,661; 37,186) for healthcare costs and <euro>15,165/QALY (7,947; 31,754) when drug costs were considered alone. A total of 94% of re-samples fell below the threshold of <euro>30,000 per QALY. This evaluation modelling suggests that pregabalin may be cost-effective in comparison with UC in outpatients with refractory GAD treated in mental healthcare settings in daily practice in Spain.