Background:The body of knowledge regarding rhinosinusitis (RS) continues to expand, with rapid growth in number of publications, yet substantial variability in the quality of those presentations. In an effort to both consolidate and critically appraise this information, rhinologic experts from around the world have produced the International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR:RS). Methods:Evidence-based reviews with recommendations (EBRRs) were developed for scores of topics, using previously reported methodology. Where existing evidence was insufficient for an EBRR, an evidence-based review (EBR) was produced. The sections were then synthesized and the entire manuscript was then reviewed by all authors for consensus. Results:The resulting ICAR:RS document addresses multiple topics in RS, including acute RS (ARS), chronic RS (CRS) with and without nasal polyps (CRSwNP and CRSsNP), recurrent acute RS (RARS), acute exacerbation of CRS (AE-CRS), and pediatric RS. Conclusion:As a critical review of the RS literature, ICAR:RS provides a thorough review of pathophysiology and evidence-based recommendations for medical and surgical treatment. It also demonstrates the significant gaps in our understanding of the pathophysiology and optimal management of RS. Too o en the foundation upon which these recommendations are based is comprised of lowerlevel evidence. It is our hope that this summary of the evidence in RS will point out where additional research efforts may be directed. C 2016 ARS-AAOA, LLC. Key Words:rhinosinusitis; chronic rhinosinusitis; acute rhinosinusitis; recurrent acute rhinosinusitis; evidence-based medicine; systematic review; endoscopic sinus surgery List of Abbreviations Used

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

I. Executive Summary Background The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS.

Objective Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a disease process that is driven, in part, by intrinsic mucosal inflammation. Surgery plus continued medical therapy is commonly elected by medically recalcitrant, symptomatic patients. The objective was to evaluate the prevalence of nasal polyp recurrence up to 18-months after endoscopic sinus surgery (ESS) with congruent continuing medical management. Study Design Prospective, multi-center cohort of adult patients undergoing ESS for medically recalcitrant CRSwNP performed between August, 2004 and February, 2015. Methods All patients received baseline nasal endoscopy quantified using Lund-Kennedy grading. All patients included for final analysis provided at least 6-month postoperative endoscopy examinations. Multivariate analysis was used to identify risk factors for polyp recurrence. Results 363 CRSwNP patients having undergone ESS involving polypectomy were enrolled. A total of 244 (67%) participants had graded postoperative endoscopies with average of follow-up of 14.3[±7.0] months. Surgery plus postoperative medical management significantly improved endoscopy total scores at 6-months (p<0.001). The recurrence of nasal polyposis 6-months after ESS was 35% (68/197), compared to 38% (48/125) after 12-months, and 40% (52/129) after 18-months. Multivariate analysis identified both prior ESS (OR=2.6, 95% CI: 1.5–4.6; p=0.001) and worse preoperative polyposis severity (OR=1.4, 95% CI: 1.1–1.8; p=0.016) as risk factors for recurrent polyposis. Conclusions Polyp recurrence is common after ESS with control of polyps up to 18-months found in approximately 60–70% of patients. Investigation into both surgical and medical management strategies is warranted to improve upon the observed prevalence of recurrence.

Despite relatively low levels of evidence, recommendations for the diagnosis and management of CSF rhinorrhea can be made based on the current literature. Higher-level studies are needed to better determine optimal diagnostic and clinical management approaches.