Response to Drs. Patrick and Drossman

TO THE EDITOR: In the presentation of the irritable bowel syndrome (IBS)-36, Grollet al. (1) compare the psychometric performance of their newly developed instrument with the IBS-quality of life (QOL) that we developed (2, 3). They note that both were found to have high responsiveness to treatment, but unlike the IBS-QOL, the IBS-36 was developed using a “physician gold standard” and symptoms evaluated to establish criterion validity. In QOL research, there is no physician gold standard. Accordingly, the IBSQOL was developed using the needs-based model with QOL items that can be known only to the person with the condition. Criterion validity for such types of items does not exist; instead, careful construct validation of expected relationships was used. Furthermore, it was stated that the IBS-QOL is a proprietary instrument. That is not correct. It is jointly copyrighted by the University of Washington, University of North Carolina, and Novartis Pharmaceuticals. Although there is sufficient information in the articles to permit scoring of the instrument, we do prefer to receive written requests for our user manual, which contains a scoring program. We prefer this because it assures the quality of data entry and analysis using the IBS-QOL. Note, however, there are no restrictions with regard to access or use of this instrument. For those interested, the user manual is currently available by e-mailing the principal developers whose addresses are listed below.