Baker, Arabella
(2024)
Measuring and optimising patient-reported outcomes in eczema clinical trials through the use of online methods.
PhD thesis, University of Nottingham.
Abstract
Background
Eczema is a chronic, inflammatory, itchy skin condition affecting 15-30% children and 2-10% adults. In randomised controlled trials (RCTs), patient-reported outcome measures (PROMs) are often used to evaluate interventions. The Harmonising Outcome Measures for Eczema (HOME) initiative developed a core outcome set (COS) consisting of four core domains to be included in all eczema trials, three of which are measured with PROMs. Implementing the COS helps to improve the consistency of outcome measures and the comparability of results across eczema trials. However, the optimum frequency of PROM assessments in eczema trials is unclear, which may hinder the uptake of the full COS.
Research aims
The overall aim of the research contained in this thesis was to inform the HOME initiative by addressing research priorities and filling validation gaps in relation to PROMs to help the implementation of the COS. In addition to improving the use of PROMs in eczema trials, this thesis aims to contribute to the field of trials methodology by evaluating a participant recruitment strategy used for an RCT.
The specific research aims for each study were as follows:
1. To establish the optimum frequency of patient-reported outcome assessments in eczema trials by conducting the Eczema Monitoring Online (EMO) RCT (Chapter 3)
2. To evaluate the social media recruitment strategy used for an online eczema trial (Chapter 4)
3. To fill the content validation gap of the Recap of atopic eczema (RECAP) instrument in young people (Chapter 5)
4. To aid the interpretability of RECAP change scores (Chapter 6)
Methods
Chapter 3 describes the EMO parallel group RCT, which was conducted entirely online. It included adults and children with eczema. The trial was 8 weeks long and compared the effect of weekly PROM assessments (intervention) with baseline and week 8 assessments (control). The primary outcome was change in eczema severity. Chapter 4 presents the efficiency and costs of both paid and unpaid social media recruitment methods used in the EMO trial. Chapter 5 contains a content validity study, which assessed the relevance, comprehensiveness and comprehensibility of RECAP. Semi-structured cognitive interviews with young people aged 8-16 years were conducted in the United Kingdom, Germany and the Netherlands. Chapter 6 determines the interpretability of RECAP scores by employing both anchor-based and distribution-based statistical methods to calculate the minimal important change score and the smallest detectable change. It provides a guide for the interpretation of change scores in RECAP.
Results
In the EMO trial (n = 296) the mean between group difference was -1.64 (95% CI -2.91 to -0.38; p = 0.01), demonstrating that weekly patient-reported symptom monitoring led to a small perceived improvement in eczema severity over 8 weeks. In 4 months, the social media campaign recruited 259 participants from diverse demographic backgrounds from Reddit (n = 121), Facebook (n = 43), Instagram (n = 88) and Twitter (n = 7) for a low cost with a retention rate of 82%. For the content validity study, findings indicate that RECAP is suitable for self-completion in children aged ≥12 years and using the proxy completed version for children younger than 12 years is advised. In terms of interpretability of RECAP, a change score of 1.9 or below is likely to be measurement error and the change in scores needs to be 2.0 points or greater before the change is considered clinically important and meaningful.
Conclusions
Based on the EMO trial results, reducing the frequency of PROM collection is recommended in future eczema trials. Using social media can be an effective tool for recruiting participants into trials. In addition, the RECAP patient-reported instrument performed well in both validation studies and appears to be fit for purpose for measuring the long-term control of eczema. The research in this PhD makes an original contribution to knowledge in the field of eczema and informs the HOME initiative in relation to the appropriate measurement of patient-reported outcomes in future eczema clinical trials.
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