A comparison of international clinical practice guidelines on adult chronic rhinosinusitis shows considerable variability of recommendations for diagnosis and treatment.

OBJECTIVES: To compare international clinical practice guidelines on adult chronic rhinosinusitis (CRS).
DESIGN: Extensive literature search in Embase, PubMed and the internet (Google, websites of well-known guideline organizations) on November 21st 2018. MAIN OUTCOME MEASURES: Guidelines' quality was measured by the AGREE II instrument. A summary and comparison of recommendations on diagnosis and treatment with harmonized levels of evidence (LoE) and grade of recommendations (GoR) is given.
RESULTS: We selected ten guidelines on CRS. Five guidelines were of sufficient to high quality according to AGREE II, the remaining guidelines predominantly did not meet AGREE II criteria. We harmonized all guideline recommendations so we could compare them, although three guidelines did not provide a LoE. Five guidelines provided recommendations on diagnosis, all of them recommended performing nasal endoscopy, CT scan and allergy testing (with varying GoRs). All ten guidelines provided recommendations on therapy, one treatment, i.e., the use of intranasal steroids, was recommended by all guidelines (with varying GoRs). Recommendations for surgical treatment of CRS were provided by five guidelines.
CONCLUSION: We performed an extensive search and included ten (inter)national guidelines on CRS for adults. According to AGREE II, five were of good or sufficient quality. Overall, there was much variation between guidelines in recommended diagnostic test or treatment, direction of evidence and GoR. We found consensus for nasal endoscopy, CT scan, allergy testing and intranasal steroids. We argue for standardization of guideline development, to increase their quality and improve comparability.