Minimization of ragweed allergy immunotherapy costs through use of the sublingual immunotherapy tablet in Canadian children with allergic rhinoconjunctivitis

Cost minimization analysis

A cost minimization analysis was conducted to determine the cost impact of the ragweed SLIT-tablet, 12 Amb a 1-U versus other AIT comparators (e.g., ragweed SCIT prepared from alum-precipitated aqueous extracts or MRPATA) in Ontario and Quebec. A cost minimization analysis was chosen as the type of economic analysis because there are no available head-to-head efficacy and safety data between the ragweed SLIT-tablet and the comparators. It was conservatively assumed that the ragweed SLIT-tablet and the AIT comparators were therapeutically equivalent, despite evidence that SLIT has a more favorable safety profile than SCIT [14, 15]. The use of symptom-relieving medications for ARC symptoms was not included in the analysis based on the assumption that their use would be the same among the evaluated AIT options.

The analysis was conducted over a time horizon of 3 years, which is the minimum recommended duration of AIT treatment for seasonal pollens [8, 20]. The benefits and costs after completing 3 years of treatment were assumed to be the same for the ragweed SLIT-tablet and the AIT comparators. A public payer perspective relevant to Ontario or Quebec was adopted to estimate costs; therefore, no patient resources or costs (i.e., travel time/costs) were included in the base case model. A discount rate of 1.5% was applied in the base case model in accordance with Canadian economic evaluation guidelines [21].

The input values for the model were obtained from published literature and validated by Canadian clinical experts in active allergy practice.

Model resource inputs

Medication resources and services of healthcare professionals were considered for each treatment included in the analysis. These resources for the ragweed SLIT-tablet, ragweed SCIT, and MRPATA over a 3-year treatment period are summarized in Table 1.

Table 1 Model resource inputs for medication and services of healthcare professionals in Ontario and Quebec

Medication resource use was assumed to be the same for Ontario and Quebec. Using information from the Health Canada product monograph [12] for the base case analysis it was assumed that the ragweed SLIT-tablet would be taken once daily during the pre-season (starting at least 12 weeks before the pollen season) and continued through the pollen season, for a duration of 6 months [22] This regimen was assumed to be repeated for years 2 and 3. There were 2 SCIT regimens compared in the analysis. The first SCIT regimen was pre-ragweed pollen season (preseasonal) monotherapy. The duration of preseasonal SCIT varies in practice from 8 to 13 weeks; a conservative estimate of 11 weekly preseasonal injections given during the titration phase, with 1 week between injections, and no yearly maintenance injections was assumed for the base case analysis. These assumptions were validated by Canadian clinical experts as representative of preseasonal SCIT treatment. The preseasonal SCIT regimen was assumed to be repeated for years 2 and 3. The second SCIT regimen was annual treatment, in which a base case of 25 weekly titration injections were assumed with 1 week between injections, followed by maintenance injections every 4 weeks. It was assumed that one 10 mL vial would last for 10 injections [23]. MRPATA was assumed in the base case to be administered by a healthcare provider in 4 weekly preseasonal injections. This regimen was assumed to be repeated for years 2 and 3.

The services of physicians and nurses are required in the assessment, prescribing, and administration of the ragweed SLIT-tablet, ragweed SCIT, and MRPATA. A key difference in healthcare resource use among the AIT options is that after the first dose is administered in the clinic, the ragweed SLIT-tablet is administered at-home. Therefore, for Ontario it was assumed that there would be one initial visit each year with a physician (95% specialist, 5% general practitioner) for the ragweed SLIT-tablet, as well as 30 min of observation time with a nurse. For Quebec, no nurse observation time was included in the base case analysis of the ragweed SLIT-tablet because it is not covered by the Régie de l’assurance maladie du Québec. In both Ontario and Quebec, one physician (90% specialist, 10% general practitioner) follow-up visit at the end of the treatment season was assumed for the ragweed SLIT-tablet. For Ontario, each ragweed SCIT injection and MRPATA injection was assumed to be associated with a physician injection administration fee, a physician consultation, and 30 min of observation time with a nurse. For Quebec, no nurse observation time was included in the base case analysis of ragweed SCIT or MRPATA because it is not covered by the Régie de l’assurance maladie du Québec. For the base case analysis for both Ontario and Quebec, it was assumed that 90% of patients visited a specialist and 10% visited a general practitioner for the ragweed SCIT titration visits, 5% visited a specialist and 95% visited a general practitioner for ragweed annual SCIT maintenance visits, and that 20% of patients visited a specialist and 80% visited a general practitioner for the MRPATA visits.

Model cost inputs

Costs associated with medication and services of healthcare professionals were considered for each treatment included in the analysis. All costs are in Canadian dollars. The costs for the ragweed SLIT-tablet, ragweed SCIT, and MRPATA over a 3-year treatment period for Ontario and Quebec are summarized in Table 2.

Table 2 Model cost inputs for medication and services of healthcare professionals in Ontario and Quebec

The medication costs were obtained from the manufacturer submitted price for the ragweed SLIT-tablet, from the Régie de l’assurance maladie du Québec [24] for ragweed SCIT, and the Association québécoise des pharmaciens propriétaires [25] for MRPATA. There are multiple inputs for ragweed SCIT costs as there are varied formulations for pre-seasonal and annual treatments. The mark-up for Ontario (8%) and Quebec (6.5%) was obtained from the Patented Medicine Prices Review Board [26]. The dispensing fee for Ontario ($8.83/claim) was obtained from the Ontario Ministry of Health and Long-Term Care [27] and for Quebec ($9.94/claim) was obtained from Patented Medicine Prices Review Board [26]. It was assumed that the costs did not change over the 3-year time horizon of the analysis.

Costs for physician services in Ontario were obtained from the Ontario Schedule of Benefits and Fees [28] and for Quebec were obtained from the RAMQ Manuel des Médecins Spécialistes [29]. Costs for nurse services in Ontario were obtained from the Ontario Nurses’ Association collective agreement (assumes 8 years experience, $48.17/hour plus 4.8% for vacation and 13% for fringe benefits, totaling $56.74/hour) [30].

Scenario analyses

Several scenario analyses were conducted to determine the impact of many of the key base case assumptions on the outcomes. The different scenarios examined variable discount rates, more MRPATA injections, a lower proportion of specialist titration visits for ragweed SCIT, shorter ragweed SLIT-tablet treatment course, more or less nurse times per SCIT injection (for Ontario only since nursing costs are not covered in Quebec), exclusion of markup and dispensing fees, and addition of nursing costs for Quebec. Scenarios were also considered that assessed the economic impact of the ragweed SLIT-tablet from a societal or patient perspective rather than the payer perspective used in the base case analysis. The patient resources assumed for the societal or patient perspective scenario include patient time lost for office visits and travel distance, details of which are described in Additional file 1: Table S1. The assumed patient costs associated with time lost were an average hourly wage (as of December 2022 for individuals aged 16 years and older) of $30.49 in Ontario and $24.39 in Quebec obtained from Statistics Canada [31]. The assumed cost associated with travel distance by private car for the first 5000 km driven was $0.59 in Ontario and $0.47 per kilometer in Quebec obtained from the Canadian 2020 Reasonable Kilometer-Allowance rates [32].

A scenario that included nurse working time was conducted for Quebec, where it was excluded from the base case scenario because of lack of public plan coverage. For this scenario, the nurse work time in hours was 0 (years 1, 2, and 3 each) for ragweed SLIT-tablet, 5.50 (years 1, 2, and 3 each) for preseasonal SCIT, 15.88 (year 1), 6.50 (year 2), and 6.50 (year 3) for annual SCIT, and 2.0 (years 1, 2, and 3 each) for MRPATA.

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