Background
The Recap of atopic eczema questionnaire (RECAP) was developed to measure eczema control in patients with atopic dermatitis (AD). Measurement properties of RECAP have not yet been validated in caregivers of children with AD.
Objectives
To assess the construct validity, responsiveness, reliability and interpretability of the Dutch proxy version of RECAP.
Methods
A prospective validation study was conducted among children (<12 years) with AD and their caregivers (in a Dutch tertiary hospital). At three time points (T0, Baseline; T1, after 1–7 days; T2, after 4–8 weeks) RECAP and multiple reference instruments were completed by caregivers of children patients. Construct validity: Single and change-score validity (responsiveness) were tested with a priori hypotheses on correlations with reference instruments. Reliability: intraclass correlation coefficients (ICCagreement) and standard error of agreement (SEMagreement) were reported. Interpretability of single scores: Bands for perceived eczema control were proposed. Interpretability of change score: The smallest detectable change (SDC) and minimally important change (MIC) were determined. Two anchor-based methods based on receiver operating characteristic curve (ROC) and predictive modelling were used to determine the MIC.
Results
A total of 231 children with AD and their caregivers participated in the study. Of our a prior hypotheses for single-score and change-score validity, 77% and 80% were confirmed, respectively. Stronger correlation than hypothesized was found for all rejected hypotheses.
Excellent reliability was found (ICCagreement: 0.94; 95% confidence interval (CI): 0.90-0.96). The SEMagreement was 1.9 points. The final banding was: 0-1 (completely controlled), 2-7 (mostly controlled), 8-12 (moderately controlled), 13-18 (a little controlled), 19-28 (not at all controlled). A cut-off point of ≥8 was selected to identify children whose AD is not under control. The SDC was 5.3 and the MIC value 1.5 and 3.6 for the ROC and predictive modelling approach respectively. No floor or ceiling effects were observed.
Conclusions
The proxy version of RECAP is a valid, reliable and responsive measurement instrument for measuring eczema control in children with AD. An improvement of ≥6 points can be regarded as real and important change in children with AD.