Capturing and reporting topical treatment use in childhood eczema: lessons for data collection in eczema trials.

While questionnaire completion was similar for TCS use, emollient use data completeness was higher in the second version. When designing questionnaires, balancing the detail and complexity of questions is important, especially if being collected as a secondary outcome measure. Numerous ways of summarising the same data can provide different information. Future collection and reporting of treatment use should reflect specific trial aims.