Development and initial testing of a new instrument to measure the experience of eczema control in adults and children: Recap of atopic eczema (RECAP)

Abstract

Background: Eczema control has been identified as an important outcome by key stakeholders in eczema research (including patients, carers, healthcare professionals and researchers) but no validated instruments for the domain have been identified.

Objectives: To develop a measurement instrument to capture a patient's perspective of eczema control that is suitable for use in eczema clinical trials.

Methods: Best practice for the development of a patient-reported outcome was followed. A mixed-methods approach was used to develop and refine a conceptual framework, generate, refine and select items and to test the distribution and construct validity of the final scale. The mixed-methods approach involved expert panel meetings (including patient representatives, healthcare professionals and methodologists), and data collection using a focus group, cognitive interviews and an online survey with people with eczema and caregivers. Multivariable linear regression was used in the item selection process.

Results: Fourteen expert panel members co-produced the instrument, with input from people with eczema and caregivers via a focus group (n = 6), cognitive interviews (n = 13) and an online survey (n = 330). The resulting instrument, Recap of atopic eczema (RECAP), is a seven-item questionnaire that captures eczema control via self or caregiver report. The development process aimed to ensure good content validity and feasibility. Initial testing suggested no floor or ceiling effects and good construct validity. Hypothesized correlation with the Patient-Oriented Eczema Measure was confirmed [r(258) = 0·83, P < 0·001].

Conclusions: RECAP has the potential to improve reporting of eczema control in research and clinical practice. Further exploration of measurement properties is required. Linked Comment: Pattinson and Bundy. Br J Dermatol 2020; 183:418-419. What's already known about this topic? Eczema control has been identified as an important outcome by key stakeholders in eczema research (including patients, carers, healthcare professionals and researchers). Qualitative studies suggest eczema control is a multifaceted and individual experience and no instrument has been identified that captures eczema control in this way. What does this study add? We have developed Recap of atopic eczema (RECAP), a seven-item questionnaire to capture the experience of eczema control in all ages and eczema severities; there are two versions: a self-reported version for adults and older children with eczema, and a caregiver-reported version for younger children with eczema. Designed with input from people with eczema, caregivers and healthcare professionals to ensure good content validity. Initial testing of score distributions and construct validity suggests good measurement properties. What are the clinical implications of the work? The RECAP instrument is appropriate and feasible for measuring eczema control in clinical trials and may also be useful in routine practice.

Figure 1

Study design for developing Recap of atopic eczema (RECAP).

Figure 2

Initial conceptual framework discussed at focus group.

Figure 3

Final conceptual framework. Note. The direction of the arrows indicates that a formative measurement model is most appropriate to use.

Figure 4

Recap of atopic eczema (RECAP) questionnaire (copyright retained by authors): (a) self‐reported version and (b) caregiver‐reported version.

Figure 5

Distribution of scores on final instrument, n = 264.