|Analytic model comparing the cost utility of TVT versus duloxetine in women with urinary stress incontinence
|Jacklin P, Duckett J, Renganathan A
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
This study assessed the cost-effectiveness of duloxetine versus tension-free vaginal tape as the second-line treatment for urinary stress incontinence, using new data on drug discontinuation rates. The authors concluded that tension-free vaginal tape was more cost-effective than duloxetine and was below the recommended threshold for cost-effectiveness in the UK after four years. The study was based on several assumptions that were required to assess the long-term impact of the two treatments and caution is required when interpreting the authors’ conclusions.
Type of economic evaluation
This study assessed the cost-effectiveness of duloxetine, in comparison with tension-free vaginal tape, as the second-line treatment for urinary stress incontinence, using new data on drug discontinuation rates.
Drug therapy with duloxetine hydrochloride (40mg twice daily) was compared with the surgical application of tension-free vaginal tape. The background strategy was no intervention.
The analysis was based on a Markov model with a two-year time horizon. The authors stated that the study was carried out from the perspective of the UK National Health Service (NHS).
The clinical inputs were from selected sources. The surgery success rates were from a randomised trial and another economic evaluation. The primary input was the discontinuation rate, associated with drug therapy, due to adverse events, and this was from a cohort study. Other data on drug efficacy were from a published cost-effectiveness analysis and some assumptions were also required.
Monetary benefit and utility valuations:
The utility values were from a published cost-effectiveness analysis, which assumed the gain in quality-adjusted life-years (QALYs) as a result of successful treatment.
Measure of benefit:
QALYs were the summary benefit measure and they were discounted at a rate of 3.5% for the second year of the model.
The analysis included the costs of general practitioner visits, gynaecology follow-up visit, duloxetine, tension-free vaginal tape, preoperative assessment, and urodynamics. The resource use data were based on authors’ opinions. The costs were from published UK sources, such as the Unit Costs of Health and Social Care, NHS reference costs, NHS tariffs, and the British National Formulary. All costs were reported in UK pounds sterling (£) and in US dollars ($). A 3.5% annual discount rate was applied to those costs incurred during the second year. The price year was 2007.
Analysis of uncertainty:
One-way sensitivity analyses were carried out on the time horizon, the cost of the tape, the QALY gain, and the surgery success rate. Published estimates from alternative sources and authors’ opinions were used.
With no intervention, there was assumed to be no costs and no QALYs.
Over two years, the expected costs were £238 with duloxetine, and £3,033 with tape, and QALYs were 0.0067 with duloxetine, and 0.0869 with tape. Compared with no intervention, the incremental cost per QALY gained was £35,485 ($58,227) with duloxetine, and £34,841 ($57,170) with tape, suggesting that neither of these two strategies was within the National Institute for Health and Clinical Excellence (NICE) threshold of £20,000 per QALY, but tape performed better than duloxetine, which was less cost-effective and less effective (extendedly dominated).
In some scenarios, compared with no intervention, tension-free vaginal tape was cost-effective, at the £20,000 per QALY threshold. These scenarios were: in a 10-year analysis (£7,710 per QALY) or one longer than four years; when the cost was below £1,033; and when the QALY gain from cure was 0.09. The incremental cost per QALY with duloxetine, compared with no intervention, was £21,019 after 10 years.
The authors concluded that tension-free vaginal tape was more cost-effective than duloxetine and it was below the recommended threshold for cost-effectiveness in the UK after four years.
The selection of the comparators was appropriate. The surgical strategy was the only available therapy for women, who had failed the pelvic floor muscle therapy, for stress incontinence, until the introduction of duloxetine, which was the first licensed drug for this problem. No intervention was also included and was assumed to have no costs and no benefits.
The clinical analysis was not fully reported, especially the sources of data, which were only partly described, limiting the possibility of making an objective assessment of the quality of this evidence. The authors justified the use of several assumptions, which were generally required due to a lack of published data on the long-term impact of the treatments. The disorder has a big impact on patients’ quality of life and the use of QALYs was valid. The authors stated that a conservative estimate was used for the utility values, based on a published study, but the methods of this study were not reported. Variations in the utility gains were considered in the sensitivity analysis.
The categories of costs were appropriate for the perspective of the public payer. The unit costs and key quantities of resources were reported, as was the price year. Appropriate sources of data were selected and the costs represented conventional NHS prices. Surgical complications were excluded because they were rare, but these might have had an impact on the cost-effectiveness results. Changes in the economic inputs were not extensively investigated.
Analysis and results:
The results were clearly reported and synthesised in both average and incremental ratios. The issue of uncertainty was only partially investigated, as the sensitivity analyses focused on selected uncertain inputs to the model. A simultaneous assessment of various aspects of uncertainty would have been interesting. Some simplifying assumptions were required, especially for the long-term data, and the authors pointed out the impact of variations in these assumptions on their results.
The study was based on several assumptions that were required to assess the long-term impact of the two treatments and caution is required when interpreting the authors’ conclusions.
Jacklin P, Duckett J, Renganathan A. Analytic model comparing the cost utility of TVT versus duloxetine in women with urinary stress incontinence. International Urogynecology Journal 2010; 21(8): 977-984
Subject indexing assigned by NLM
Cost-Benefit Analysis; Duloxetine Hydrochloride; Female; Humans; Markov Chains; Models, Statistical; Quality-Adjusted Life Years; Sensitivity and Specificity; Serotonin Uptake Inhibitors /economics /therapeutic use; Suburethral Slings /economics; Thiophenes /economics /therapeutic use; Treatment Outcome; Urinary Incontinence, Stress /economics /therapy
Date bibliographic record published
Date abstract record published