Validation of treatment escalation as a definition of atopic eczema flares.

BACKGROUND

Atopic eczema (AE) is a chronic disease with flares and remissions. Long-term control of AE flares has been identified as a core outcome domain for AE trials. However, it is unclear how flares should be defined and measured.

OBJECTIVE

To validate two concepts of AE flares based on daily reports of topical medication use: (i) escalation of treatment and (ii) days of topical anti-inflammatory medication use (topical corticosteroids and/or calcineurin inhibitors).

METHODS

Data from two published AE studies (studies A (n=336) and B (n=60)) were analysed separately. Validity and feasibility of flare definitions were assessed using daily global bother (scale 0 to 10) as the reference standard. Intra-class correlations were reported for continuous variables, and odds ratios and area under the receiver operator characteristic (ROC) curve for binary outcome measures.

RESULTS

Good agreement was found between both AE flare definitions and change in global bother: area under the ROC curve for treatment escalation of 0.70 and 0.73 in studies A and B respectively, and area under the ROC curve of 0.69 for topical anti-inflammatory medication use (Study A only). Significant positive relationships were found between validated severity scales (POEM, SASSAD, TIS) and the duration of AE flares occurring in the previous week - POEM and SASSAD rose by half a point for each unit increase in number of days in flare. Smaller increases were observed on the TIS scale. Completeness of daily diaries was 95% for Study A and 60% for Study B over 16 weeks).

CONCLUSION

Both definitions were good proxy indicators of AE flares. We found no evidence that 'escalation of treatment' was a better measure of AE flares than 'use of topical anti-inflammatory medications'. Capturing disease flares in AE trials through daily recording of medication use is feasible and appears to be a good indicator of long-term control.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN71423189 (Study A).