Discussion
Projections over patient lifetimes based on two randomized controlled trials suggested that once-weekly semaglutide would improve clinical outcomes compared with insulin glargine U100 and dulaglutide for treatment of people with type 2 diabetes. These improvements were achieved at an increased cost from a societal perspective versus insulin glargine U100 but at a reduced cost from a societal perspective versus dulaglutide. Decision-making around reimbursement of interventions which improve outcomes and reduce costs is straightforward, but decision-making when interventions improve outcomes and increase costs is more nuanced, requiring assessment of whether the additional benefits are worth the additional costs. These value-for-money assessments can be made by comparing the ICER generated in the analysis with a willingness-to-pay threshold, representing the maximum amount an individual or society is prepared to pay in order to gain 1 QALY. A number of willingness-to-pay thresholds have been suggested for the Netherlands, with €20 000 per QALY gained often quoted, and discussion of a willingness-to-pay threshold of €80 000 per QALY gained for very severe diseases.32 A study attempting to identify the willingness-to-pay threshold of individuals in the Netherlands found that the willingness-to-pay threshold ranged from €12 900 per QALY gained to €24 500 per QALY gained, depending on the measure used to assess quality of life.33 All base case ICERs versus insulin glargine U100 and dulaglutide in the present analysis fell below the lowest willingness-to-pay threshold, even with the most stringent definition of value for money in the Netherlands. Use of once-weekly semaglutide for treatment of patients with type 2 diabetes in the Netherlands is, therefore, likely to be a good use of healthcare resources.
At present, reimbursement of GLP-1 receptor agonists in the Netherlands is limited to people with type 2 diabetes with a BMI≥35 kg/m2 whose blood glucose values cannot be adequately regulated with the combination of metformin and a sulfonylurea, and those with a BMI≥30 kg/m2 who do not achieve blood glucose targets with optimally titrated basal insulin in combination with metformin (with or without a sulfonylurea).10 The present analysis assessed outcomes in all patients in the base case analyses, in line with the inclusion criteria of the SUSTAIN 4 and 7 clinical trials. In the SUSTAIN 4 and 7 trials, mean BMI was 33.01 and 33.50 kg/m2, respectively, and therefore a number of patients would meet the reimbursement criteria for a GLP-1 receptor agonist, but others would not. To investigate the impact of baseline BMI on cost-effectiveness, the present analysis included subgroup analyses in patients with BMI ≥30 and ≥35 kg/m2. These analyses showed that once-weekly semaglutide is likely to be cost-effective in all patient groups analyzed and therefore is likely to be a good use of healthcare resources in patients with a BMI≥30 kg/m2.
Cost-effectiveness analyses in other country settings support the results of the present analysis. An evaluation based on SUSTAIN 7 for the UK found that both doses of once-weekly semaglutide were dominant versus dulaglutide from a healthcare payer perspective.27 Similarly, in an analysis prepared for the Canadian setting (using a different health economic model), once-weekly semaglutide 0.5 mg was dominant versus dulaglutide 0.75 mg and once-weekly semaglutide 1 mg was dominant versus dulaglutide 1.5 mg.34 In Estonia, a cost-effectiveness analysis has suggested that once-weekly semaglutide is cost-effective versus liraglutide, improving clinical outcomes with only a small increase in costs.35 An analysis for Denmark found that once-weekly semaglutide 0.5 mg and 1 mg were either cost-effective or dominant versus a range of GLP-1 receptor agonists.36 Numerous factors may influence the cost-effectiveness of interventions in different countries, including pharmacy costs, costs of treating complications, and healthcare funding models, but once-weekly semaglutide appears to be consistently cost-effective in a range of countries. To date, no other studies have assessed the cost-effectiveness of once-weekly semaglutide versus insulin glargine U100 based on SUSTAIN 4.
There is increasing interest in the impact of GLP-1 receptor agonists on cardiovascular risk. Efficacy appears to vary between GLP-1 receptor agonists, with once-weekly semaglutide, liraglutide, dulaglutide and albiglutide shown to reduce the risk of cardiovascular events, but lixisenatide and exenatide extended release shown to have no impact compared with placebo.37–42 It was not possible to take into account the impact of interventions on cardiovascular risk in the present analysis, as risk equations based on the cardiovascular outcome studies have not yet been integrated into cost-effectiveness models. Exclusion of the direct cardioprotective effect observed with semaglutide, particularly in the comparison with insulin glargine U100 which has been shown to have no cardioprotective effect, is a conservative approach, with a modeling study based on the SUSTAIN 6 trial showing that conventional risk equations underestimate the reduced incidence of stroke with once-weekly semaglutide.43 The cardiovascular outcome trials in type 2 diabetes have been conducted in patients with varying characteristics, most notably with differing cardiovascular risk profiles at baseline. Studies in homogeneous populations are required to assess the relative impact of different GLP-1 receptor agonists on cardiovascular risk, and subsequently capture any differences in risk equations for use in health economic analyses. Nevertheless, the cardiovascular benefits for semaglutide reported in the SUSTAIN 6 study may increase the cost-effectiveness of once-weekly semaglutide, particularly in comparison with insulin glargine U100.
As with many health economic analyses of interventions for type 2 diabetes, a limitation of the present analysis was the use of short-term data to project long-term outcomes. However, modeled projections represent the best available option for healthcare decision-making in the absence of long-term clinical trial data. Projection of outcomes over patient lifetimes is recommended in guidelines for assessing the cost-effectiveness of diabetes interventions, and the present analysis attempted to mitigate the inherent uncertainty through use of a published and extensively validated model and through preparation of extensive sensitivity analyses.13–16
A further limitation of the analysis was that adherence and persistence were not captured. There are currently no data to inform rates of adherence and persistence with once-weekly semaglutide, dulaglutide and insulin glargine U100 over the long term. There are also no data to inform how risk factors, such as HbA1c and BMI would be affected by non-adherence and non-persistence. Similarly, switching between doses of GLP-1 receptor agonists and titration of the insulin glargine U100 was not captured, as there are no data available to inform rates of switching or titration, or the subsequent changes in risk factors. Further studies in real-world clinical practice are required to examine adherence, persistence and changes in dose, and how these affect risk factors for diabetes-related complications, with these data then included in further evaluations of cost-effectiveness.