xRead - Olfactory Disorders (September 2023)

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PATEL et al.

there were 13,618 publications, with 2325 in the year 2020 alone. Although basic science research is integral to our under standing of the system and invaluable in creating the foun dation for any translational or clinical study, with the vast amount of literature to evaluate, we decided to limit this document to the existing clinical knowledge in the field of olfaction. Similar to other International Consensus in Allergy and Rhinology (ICAR) documents on chronic rhi nosinusitis (CRS) and allergic rhinitis (AR), 4–6 our goal with producing this document is to summarize the best external evidence to provide practitioners the means to practice evidence-based medicine when diagnosing and treating these patients. As is the case among many fields of medicine, especially those that affect patients less com monly, the quality of the existing clinical literature pub lished on olfactory loss and dysfunction is highly variable, with studies ranging from well-designed randomized con trolled clinical trials to summaries of expert opinion and conjecture. The goal of this International Consensus of Allergy and Rhinology: Olfaction (ICAR:O) was to criti cally review the literature for olfaction-related epidemi ology, psychological and social burden, pathophysiology, evaluation and diagnosis, and management. With the management of olfactory loss or dysfunction being an inherently multidisciplinary field, we endeavored to include authors from a wide array of expertise to ensure the highest and most insightful coverage of the subject. More than 50 international authors undertook a structured review of the literature in nearly 100 topic areas related to olfaction. Although highly dependent on the quality of the existing literature, wherever possible recommen dations based on the evidence were made, with benefit, harm, and cost considerations reported. However, as noted in prior ICAR documents, this document is not a clin ical practice guideline and not a meta-analysis. In fact, because of the wide heterogeneity of the data and report ing measures found in the literature in this field, a meta analysis would not be appropriate or possible. Many of our current treatment paradigms are based on relatively weak external evidence, illustrated by the wide variation in treatment methodology that exists around the globe for these patients. When we do not have high-level evidence on which to base our practice decisions, it is in our best interest as clinicians and scientists to identify the gaps in our current knowledge and attempt to design and perform studies that can help fill those gaps and therefore better help our patients. As stated in all prior ICAR documents, this document should not be considered as determining a standard of care or medical necessity and cannot be thought of as dictating care for any individual patient. Each patient has their own

unique history, background, demographic, and clinical cir cumstances that may affect the evaluation and treatment of their specific olfactory loss or dysfunction. Finally, the idea of creating a document such as this, which strives to gather and review all of the existing clinical evidence on olfactory loss and dysfunction, is that by identifying the areas that need more research, more research will then be performed, and thus the evidence and recommendations made herein will change over time and revisions will be made to them appropriately.

II METHODS A Topic Development

All ICAR documents follow the formula of literature review described in 2011 by Rudmik and Smith, 7 utiliz ing their method of iterative evidence-based review (EBR) with recommendations (EBRRs). The literature was ana lyzed, assessed for level of evidence (LOE), and, when appropriate, recommendations were given. The subject matter of clinical olfaction was divided into 75 topics. Each topic area was assigned a senior author, rec ognized as an expert in the field. Authors were selected based on prior authorship of significant contributions to the olfactory literature and were selected from the fields of rhinology, neurology, and chemosensory science. Depend ing on the type of topic and the quality of evidence avail able in each topic, the section author was assigned either a simple literature review, an EBR, or an EBRR. To provide the content for each topic, a systematic review of the literature for each topic using Ovid MED LINE (1947 to July 2020), Embase (1974 to July 2020), and Cochrane Library databases was performed using the Pre ferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) standardized guidelines. The search began by identifying any previously published systematic reviews or guidelines pertaining to the assigned topic. Because clinical recommendations are best supported by randomized controlled trials (RCTs), the search focused on identifying these studies to provide the strongest LOE. When these did not exist, observational studies were then identified. Reference lists of all identified studies were examined to ensure that all relevant studies were captured. If the authors felt as though a non–English language study should be included in the review, the article was appropri ately translated to minimize the risk of missing important data during the development of recommendations. 8 One major exception to the search window was made for the section on COVID-19–related olfactory dysfunction (OD). The evidence for this topic was rapidly evolving during the