Key words: h(a)emorrhoids, anal, core outcome set, guideline

"The Old, the New and the Ever-Changing View of Haemorrhoidal Disease Research"

With the continuous evolution of different treatments for the care of hemorrhoids, it is important that the effectiveness of (surgical) treatments is analysed in a systematic way. Clinical studies on the effectiveness of hemorrhoid interventions have used a wide range of outcomes and outcome measures. Different guidelines indicate the lack of uniformity in the definition, measurement and reporting of outcomes. As a result, optimal evidence synthesis is hampered and high quality guidelines are lacking. A solution to improve the homogeneity of result reporting on hemorrhoids is the development and use of a core outcome set. With this dissertation, we have taken an important step towards improving hemorrhoid research by developing a core outcome set for such research. Furthermore, over the past ten years several national guidelines for the treatment of hemorrhoids have been published. The most recently updated guideline is from the American colorectal surgeons. The methodological quality of these guidelines can be improved by being much more specific about the methods used to formulate their recommendations. Therefore, we have developed an international, multidisciplinary, high-quality guideline in collaboration with the European Society of Coloproctology (ESCP) that addresses both diagnostic and therapeutic modalities for the management of hemorrhoids.