Guideline Assessment Project II: statistical calibration informed the development of an AGREE II extension for surgical guidelines

Objective To inform the development of an AGREE II extension specifically tailored for surgical guidelines. Summary background data AGREE II was designed to inform the development, reporting, and appraisal of clinical practice guidelines. Previous research has suggested substantial room for improvement of the quality of surgical guidelines. Methods A previously published search in MEDLINE for clinical practice guidelines published by surgical scientific organizations with an international scope between 2008 and 2017, resulted in a total of 67 guidelines. The quality of these guidelines was assessed using AGREE II. We performed a series of statistical analyses (reliability, correlation and Factor Analysis, Item Response Theory) with the objective to calibrate AGREE II for use specifically in surgical guidelines. Results Reliability/correlation/factor analysis and Item Response Theory produced similar results and suggested that a structure of 5 domains, instead of 6 domains of the original instrument, might be more appropriate. Furthermore, exclusion and re-arrangement of items to other domains was found to increase the reliability of AGREE II when applied in surgical guidelines. Conclusions The findings of this study suggest that statistical calibration of AGREE II might improve the development, reporting, and appraisal of surgical guidelines.