Pre-validation methods for developing a patient reported outcome instrument.

The article presents a research paper which focuses on a methodological approach used in the pre-validation development of new instruments for measuring outcomes in randomized controlled trials. It discusses the importance of measurement instruments like item generation, item reduction and question formatting. The new method uses the example of the Aberdeen Glaucoma Questionnaire (AGQ) and consists of five steps including generation of a pool of items; item de-duplication and item reduction.