The international TREatment of ATopic eczema (TREAT) Registry Taskforce aims to gain greater insight into the effectiveness, safety and cost-effectiveness of photo- and systemic immuno-modulatory therapies in adult and paediatric atopic eczema patients across country borders. National research registries that collect the same data using the predefined core dataset will collaborate to reach this goal. The core dataset enhances interoperability of the national registries, allowing direct comparability of individual country data and facilitate potential data pooling between countries. The evidence derived from these registries can be used e.g. to inform treatment guidelines. The national registries may also act as platforms for biomarker discovery and stratified medicine research.

Several studies by the TREAT Registry Taskforce have been performed, see publications. New studies are ongoing (the DREAM to TREAT AD project (investigator-led, Pfizer funded)) or in their startup phase.

In the past only conventional systemic immunomodulating therapies were available for patients with atopic eczema (AE, syn. ‘atopic dermatitis’) with disease recalcitrant to topical therapies. At that time, the only systemic therapy approved by the European Medicines Agency (EMA) was cyclosporine; and only in adults. In the US, only oral corticosteroids had Food and Drug Administration (FDA) approval. In the past years new therapies specifically developed for AE have entered the market: biologicals (dupilumab, tralokinumab, lebrikizumab) and small molecules (baricitinib, upadacitinib, abrocitinib) (Drucker et al., 2022).

At the inception of the TREAT Registry Taskforce, the main evidence to inform clinical practice around systemic immunomodulating treatments was (and still is) derived from a rather small body of randomised controlled trials (RCTs) (Flohr et al., 2023, Schram et al., 2012) as well as case series (i.a. (Garritsen et al., 2015; van der Schaft et al., 2015)). For phototherapy evidence from RCTs is mostly of low quality (Musters et al., 2021). Despite this, these treatments are frequently prescribed as shown in our European and North American surveys (Proudfoot et al., 2013; Taylor et al., 2016; Totri et al., 2017; Vermeulen et al., 2020).

Criteria for clinical trials are stringent. Research in psoriasis suggests that around 30% of patients on systemic therapies entered into registries (in itself a very selected subgroup of all patients on systemic therapy) would not be eligible for a clinical trial, underscoring the value of ‘real world’ patient data (Garcia-Doval et al., 2012).

With the arrival of the new therapeutic era of biologicals and small molecules for AE, we need more evidence with regard to the effectiveness, safety and cost-effectiveness of such therapies compared to currently used treatment modalities, such as phototherapy and systemic immunomodulating drugs (cyclosporine, methotrexate, azathioprine and others).

Apart from the need for comparative real life clinical data of conventional and new therapies, clinical decision-making requires long-term follow-up data on such treatments to generate information on disease control/disease trajectory modification (even after treatment has been discontinued) and drug safety, including rare adverse events. Generation of reliable data to address these issues requires observation of large patient cohorts for several years. Comprehensive health economic evaluation of these different treatments is routinely required by many national health technology assessment organizations and third party payers to inform the allocation of health care resources. Consequently, independent prospective multi-centre registries are a logical step, as has been successfully developed in psoriasis. This is all the more important in the light of emerging evidence that suggests that industry-funded post-marketing studies, which are often conducted to detect rare adverse events, are not improving drug safety surveillance (Spelsberg et al., 2017).