How should minimally important change scores for the Patient-Oriented Eczema Measure be interpreted? A validation using varied methods.

BACKGROUND

The Patient-Oriented Eczema Measure (POEM), scored 0-28, is the core outcome instrument recommended for measuring patient-reported atopic eczema symptoms in clinical trials. To date, two published studies have broadly concurred that the minimally important change (MIC) of the POEM is three points. Further assessment of the MIC of POEM in different populations, and using a variety of methods, will improve interpretability of the POEM in research and clinical practice.

OBJECTIVES

To calculate the smallest detectable change in the POEM and estimate the MIC of the POEM using a variety of methods in a trial dataset of children with moderate-to-severe atopic eczema.

METHODS

This study used distribution-based and anchor-based methods to calculate the MIC of the POEM in children with moderate-to-severe eczema.

RESULTS

Data were collected from 300 children. The smallest detectable change was 2·13. The MIC estimates were 1·07 (using 0·2 SD of baseline POEM scores) and 2·68 (using 0·5 SD of baseline POEM scores) based on distribution-based methods; were 3·09-6·13 based on patient-/parent-reported anchor-based methods; and were 3·23-5·38 based on investigator-reported anchor-based methods.

CONCLUSIONS

We recommend the following thresholds be used to interpret changes in POEM scores: ≤ 2, unlikely to be a change beyond measurement error; 2·1-2·9, a small change detected that is likely to be beyond measurement error but may not be clinically important; 3-3·9, probably a clinically important change; ≥ 4, very likely to be a clinically important change.