Cost-effectiveness of diagnostic algorithms for peanut allergy in children

Integrating Ara h 2 sIgE with SPT reduces oral food challenges and costs in peanut allergy diagnosis: A cost comparison analysis

BACKGROUND

Peanut allergy consumes a significant volume of oral food challenges (OFC) in the diagnosis of food allergy. Two-step diagnostic algorithms involving both SPT and Ara h 2 sIgE demonstrate increased accuracy of diagnosis in modelled studies compared to peanut skin prick test (SPT) or sIgE to whole peanut, which should result in fewer OFCs. In 2015, The Royal Children's Hospital, Australia (RCH) implemented a clinical guideline using a two-step algorithm incorporating peanut SPT (3-8 mm) followed by sIgE to Ara h 2 if the clinician is considering a peanut OFC. We aimed to determine the OFC reduction in clinical practice as a result of this two-step diagnostic algorithm compared to using peanut SPT alone and perform a cost comparison between these two approaches.

METHODS

We performed an audit of all patients presenting to RCH allergy clinics undertaking assessment of peanut allergy. Adherence to the guideline, the number of OFCs required for diagnosis, and outcomes were determined. Modelled data of the same patient cohort estimated the number of OFCs that would have occurred if using peanut SPT alone. A cost comparison was performed, comparing these two approaches.

RESULTS

Eight thousand, eight hundred and twenty-six patients were included, with 9.2% proceeding to an OFC. Of these, 20.1% had a positive result (any allergic reaction), and anaphylaxis occurred in 1.1%. There was a reduction of 27.8% in OFCs when using the diagnostic algorithm compared to SPT alone. Using the diagnostic algorithm also resulted in a 32.05% cost reduction compared to the SPT-only pathway. Sensitivity analysis demonstrated the number of OFCs gives the greatest impact to the overall cost of diagnosis.

CONCLUSIONS

A combined algorithm incorporating peanut SPT followed by sIgE to Ara h 2 resulted in a reduction in patients requiring OFCs and a cost saving in a clinical cohort.

Cost-Effectiveness of Food Allergy Interventions in Children: A Systematic Review of Economic Evaluations

OBJECTIVES

To identify published economic evaluations of interventions aimed at preventing, diagnosing, or treating food allergies in children.

METHODS

We examined economic evaluations published from 2000 to 2019. Data analyzed included: food allergy type, study population/setting, intervention/comparator, and economic evaluation details. Quality assessment used reporting and economic modeling checklists. Two reviewers simultaneously undertook article screening, data extraction, and quality assessment.

RESULTS

17 studies were included: 8 peanut allergy (PA) studies, 8 cow's milk allergy (CMA) studies, and 1 egg allergy (EA) study. All PA studies reported incremental costs per quality-adjusted life-year gained for diagnostic strategies, management pathways for peanut exposure, and immunotherapies. Immunotherapies rendered inconsistent cost-effectiveness results. CMA studies reported costs per symptom-free day or probability of developing CMA tolerance. Cost-effectiveness of extensively hydrolyzed casein formula for CMA treatment was consistently demonstrated. Early introduction of cooked egg in first year of life dominated all EA prevention strategies. Quality assessment showed average noncompliance for 3.5 items/study (range 0-11) for modeling methods and 3.4 items/study (range 0-8) for reporting quality. Key quality concerns included limited justification for model choice, evidence base for model parameters, source of utility values, and representation of uncertainty.

CONCLUSION

Recent cost-effectiveness literature of interventions in PA, CMA, and EA is limited and diverse. Interventions for diagnosis and treatment of CMA and prevention of EA were generally cost-effective; however, results for PA were variable and dependent on effectiveness and utility values used. There is a need to expand economic evaluation of interventions for childhood food allergy and to improve methods and reporting.

Diagnostic accuracy of Ara h 2 for detecting peanut allergy in children

Background

Specific IgE to Ara h 2 is a diagnostic test for peanut allergy which may reduce the need for double‐blind placebo‐controlled food challenges (DBPCFC); however, guidance for using Ara h 2 in place of DBPCFCs has not been validated.

Objective

To prospectively evaluate 1) diagnostic accuracy of previously published Ara h 2 cut‐off levels to diagnose peanut allergy in children and 2) costs.

Methods

A consecutive series of 150 children age 3.5 to 18 years was evaluated in secondary and tertiary settings in the Netherlands. sIgE to Ara h 2 was the index test, and oral peanut ingestion was the reference test. Oral peanut ingestion was home or supervised introduction for Ara h 2 ≤ 0.1, DBPCFC for 0.1–5.0 and open food challenge for ≥5.0. Costs were calculated using financial healthcare data.

Results

A conclusive reference test was performed in 113 children (75%). Sixty‐four children (57%) had peanut allergy, as confirmed by a DBPCFC (27/47) or an open challenge (37/50). Forty‐nine children (43%) were considered peanut‐tolerant after peanut introduction (19/19), a DBPCFC (20/47) or an open challenge (10/50). Area under the curve for Ara h 2 was 0.94 (95% CI 0.90–0.98). The diagnostic flow chart correctly classified 26/26 (100%; 84–100) of children with Ara h 2 ≤ 0.1 as peanut‐tolerant and 34/35 (97%; 83–100) of children with Ara h 2 ≥ 5.0 as peanut‐allergic. At a cut‐off of ≤0.1 and ≥5.0, a sensitivity of respectively 100% (93–100) and 53% (38–67) was observed and a specificity of 53% (38–67) and 98% (87–100). Mean annual costs of the flow chart were estimated as €320‐€636 per patient lower than following national allergy guidelines.

Conclusions

In this diagnostic accuracy study, which did not take into account pretest probability, we have validated previously published Ara h 2 cut‐off levels which are associated with peanut tolerance and allergy.