Comparison of patient (POEM), observer (EASI, SASSAD, TIS) and corneometry measures of emollient effectiveness in children with eczema: findings from the COMET feasibility trial

Summary Background Eczema affects around 20% of children, but multiple different outcome measures have hampered research into the effectiveness of different treatments. Objectives To compare the change in scores and correlations within and between five measures of eczema severity: Patient‐Orientated Eczema Measure (POEM), Eczema Area and Severity Index (EASI), Six Area, Six Sign Atopic Dermatitis (SASSAD), Three Item Severity (TIS) and skin hydration (corneometry). Methods Data from a feasibility trial that randomized young children with eczema to one of four emollients were used. Participants were followed for 3 months (84 days). Descriptive statistics (by emollient over time) and Spearman's correlation coefficients comparing scores at each time point and absolute change (between adjacent time points) for each outcome measure were calculated. Results In total, 197 children, mean ± SD age 21·7 ± 12·8 months, were randomized. POEM and TIS appeared to capture a range of eczema severity at baseline, but only POEM had close approximation to normal distribution. Mean POEM, EASI, SASSAD and TIS scores improved month by month, with POEM showing the greatest sensitivity (effect size 0·42). Correlations within POEM, EASI, SASSAD and TIS were moderate to good, decreasing over time. Correlations between measures were strongest for EASI, SASSAD and TIS. By contrast, corneometry scores were more variable, correlated less well over time and were poorly correlated with the other measures. Conclusions Except for corneometry, all measures appear to change in relation to emollient use over time and correlate well with themselves. POEM demonstrated the greatest range of scores at baseline and change in eczema severity over the first 28 days. What's already known about this topic? There are many different patient‐ and observer‐reported measures of eczema severity, with different levels of evidence for the measurement properties for each instrument. The value of ‘objective’ measures of skin hydration is also unclear. POEM and EASI have been recommended by the Harmonising Outcome Measures for Eczema initiative as core outcomes for all clinical eczema trials, but they have not been widely used in community settings or populations with mild eczema. What does this study add? In children with mostly mild‐to‐moderate eczema randomized to one of four emollients for 12 weeks, POEM, EASI, SASSAD and TIS all showed a reduction in eczema severity, but skin hydration (corneometry) did not