Implications for service provision
No recommendations for service provision can be made based on the analyses included in this report. The clinical effectiveness and cost-effectiveness of using multiplex allergen testing in the investigation of people with difficult to manage allergic disease have yet to be adequately investigated. In particular, the clinical consequences of changes to diagnosis or treatment and the frequency and relevance of clinically false-positive sensitisations have been under investigated. From the limited evidence available it appears that the most likely role of multiplex allergen testing would be to replace some or all single IgE testing. The ability of multiplex testing to simultaneously identify multiple antibodies in the serum samples, combined with its ability to identify which homologous allergens are cross-immunoreactive, means that these tests have the potential to provide a lot of information in a single step. Although confirmatory testing (SPT or OFC) is still likely to be required, multiplex testing could be used to tailor confirmatory testing to the individual patient and thus reduce the overall testing burden; no studies were identified that assessed overall testing burden. It should be noted that all of the evidence identified related to one test (ImmunoCAP ISAC) and conclusions on the potential utility of multiplex allergen testing may not be generalisible to other products.
Suggested research priorities
There remains considerable uncertainty about the possible role of multiplex allergen testing in the investigation of people with difficult to manage allergic disease in the UK. The formulation of a consensus-based protocol for the use of multiplex allergen testing may represent a useful starting point for future research. A prospective study would then be needed to investigate the clinical effectiveness of the proposed protocol. The preferred design would be a RCT comparing diagnostic pathways with and without multiplex allergen testing. Alternatively, an observational study to compare outcomes in centres using multiplex allergen testing to those using diagnostic pathways without multiplex allergen testing may also be a useful approach. Such an approach would, however, require careful consideration of between-centre differences in patient care pathways (other than the use of multiplex allergen testing). Outcomes measured could include:
Short-term outcomes:
diagnostic performance, including discrimination between allergens responsible for allergic reactions and those that are cross-immunoreactive, and false-positive rate (i.e. the number of sensitisations identified that are not associated with allergic response) when the full panels of multiplex allergen testing devices are used in people with difficult to manage allergic disease
treatments or management decisions (including type and duration and the use and extent of restriction diets)
overall testing burden (i.e. the total number of tests, including multiplex allergen testing, single IgE testing, SPTs and OFC tests, required to reach a diagnosis and formulate a treatment/management plan)
any AEs associated with testing.
Long-term outcomes:
If different possible methods of multiplex allergen testing are being considered, then direct head-to-head comparisons would be needed.
