Analytical Performance, Quality of Life and Costs Related to Allergy Testing: Results from Two Systematic Literature Reviews

OBJECTIVES: Many patients with allergies are misdiagnosed or undiagnosed, leading to increased morbidity, a negative impact on quality of life (QoL), and an economic burden on healthcare systems. Semi-quantitative skin prick tests (SPT) and quantitative serum immunoglobin E tests are the main tools for diagnosing allergies, with SPT results more reliant on physician interpretation. The diagnostic accuracy of allergy tests has been widely studied, but the impact of testing on costs and healthcare resource use (HCRU), and patient QoL remains underreported.

METHODS: Two systematic literature reviews (SLR) were conducted in PubMed (database inception to September 2021; any population size) and Ovid MEDLINE (January 2017 to August 2023; studies with ≥100 participants) following a pre-approved protocol to identify studies on the analytical performance, and economic and QoL impact of allergy tests. Supplementary conference searches were undertaken. Both SLRs included studies with in vivo and in vitro tests; the second SLR additionally included studies with multiple-antigen simultaneous testing.

RESULTS: Across both SLRs, 211 studies were identified, with SPT (n=93), singleplex ImmunoCAP (n=81) and CAP system tests (n=65) most commonly evaluated. Peanuts and eggs were the most frequently investigated food allergens (n=18 each), while pollen (n=56) and dust (n=40) were the most common inhalants. Diagnostic accuracy varied considerably across studies, allergens and allergen components, tests, and pre-defined thresholds. Only 27 studies reported QoL and economic data; results primarily focused on food allergies, caregiver anxiety prior to diagnosis, and the cost impact of exacerbations and anaphylaxis due to unawareness of allergies. Evidence was lacking on patient or physician preference, cost drivers, and HCRU metrics for allergy testing.

CONCLUSIONS: Data on the analytic performance of allergy tests were heterogeneous, limiting the ability to make comparisons. Robust evidence on the impact of allergy testing on economic and QoL outcomes across different allergens and testing modalities remains scarce.