International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 32181451 EPOS2020 and beyond 81 81 EN P.W. Hellings Leuven, Belgium 2366 10.4193/Rhin20.402

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 32226949 Executive summary of EPOS 2020 including integrated care pathways 82 111 EN W.J. Fokkens Department of Otorhinolaryngology, Amsterdam University Medical Centres, location AMC, Amsterdam, The Netherlands V.J. Lund Royal National Throat, Nose and Ear Hospital, UCLH, London, United Kingdom C. Hopkins Ear, Nose and Throat Department, Guys and St. Thomas’ Hospital, London, United Kingdom P.W. Hellings Department of Otorhinolaryngology, Head and Neck Surgery, University Hospitals Leuven, KU Leuven, Belgium R. Kern Department of Otorhinolaryngology - Head and Neck Surgery, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA S. Reitsma Department of Otorhinolaryngology, Amsterdam University Medical Centres, location AMC, Amsterdam, The Netherlands S. Toppila-Salmi Skin and Allergy Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland M. Bernal-Sprekelsen Department Hospital Quironsalud, University of Valencia, Valencia, Spain J. Mullol Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, IDIBAPS, Universitat de Barcelona, CIBERES, Barcelona, Catalonia, Spain 2447 10.4193/Rhin20.601 The European Position Paper on Rhinosinusitis and Nasal Polyps 2020 is the update of similar evidence based position papers published in 2005 and 2007 and 2012(1-3). The core objective of the EPOS2020 guideline is to provide revised, up-to-date and clear evidence-based recommendations and integrated care pathways in ARS and CRS. EPOS2020 provides an update on the literature published and studies undertaken in the eight years since the EPOS2012 position paper was published and addresses areas not extensively covered in EPOS2012 such as paediatric CRS and sinus surgery. EPOS2020 also involves new stakeholders, including pharmacists and patients, and addresses new target users who have become more involved in the management and treatment of rhinosinusitis since the publication of the last EPOS document, including pharmacists, nurses, specialised care givers and indeed patients themselves, who employ increasing self-management of their condition using over the counter treatments. The document provides suggestions for future research in this area and offers updated guidance for definitions and outcome measurements in research in different settings.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 Executive summary of EPOS 2020 including integrated care pathways 82 111 EN W.J. Fokkens Department of Otorhinolaryngology, Amsterdam University Medical Centres, location AMC, Amsterdam, The Netherlands V.J. Lund Royal National Throat, Nose and Ear Hospital, UCLH, London, United Kingdom C. Hopkins Ear, Nose and Throat Department, Guys and St. Thomas’ Hospital, London, United Kingdom P.W. Hellings Department of Otorhinolaryngology, Head and Neck Surgery, University Hospitals Leuven, KU Leuven, Belgium R. Kern Department of Otorhinolaryngology - Head and Neck Surgery, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA S. Reitzma Department of Otorhinolaryngology, Amsterdam University Medical Centres, location AMC, Amsterdam, The Netherlands S. Toppila-Salmi Skin and Allergy Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland M. Bernal-Sprekelsen Department Hospital Quironsalud, University of Valencia, Valencia, Spain J. Mullol Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, IDIBAPS, Universitat de Barcelona, CIBERES, Barcelona, Catalonia, Spain 2516 10.4193/Rhin The European Position Paper on Rhinosinusitis and Nasal Polyps 2020 is the update of similar evidence based position papers published in 2005 and 2007 and 2012(1-3). The core objective of the EPOS2020 guideline is to provide revised, up-to-date and clear evidence-based recommendations and integrated care pathways in ARS and CRS. EPOS2020 provides an update on the literature published and studies undertaken in the eight years since the EPOS2012 position paper was published and addresses areas not extensively covered in EPOS2012 such as paediatric CRS and sinus surgery. EPOS2020 also involves new stakeholders, including pharmacists and patients, and addresses new target users who have become more involved in the management and treatment of rhinosinusitis since the publication of the last EPOS document, including pharmacists, nurses, specialised care givers and indeed patients themselves, who employ increasing self-management of their condition using over the counter treatments. The document provides suggestions for future research in this area and offers updated guidance for definitions and outcome measurements in research in different settings.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 32172284 The socioeconomic cost of chronic rhinosinusitis study 112 125 EN N.W. Wahid Norwich Medical School, University of East Anglia, Norfolk, United Kingdom R. Smith Norwich Medical School, University of East Anglia, Norfolk, United Kingdom A. Clark Norwich Medical School, University of East Anglia, Norfolk, United Kingdom M. Salam The Ipswich Hospital, Ipswich, United Kingdom C.M. Philpott Norwich Medical School, University of East Anglia, Norfolk, United Kingdom 2361 10.4193/Rhin19.424 Introduction: Chronic rhinosinusitis (CRS) is highly prevalent, affecting 11% of the population. Studies evaluating the socio-economic impact of CRS are mostly limited to the US population. Currently there is no study that has evaluated the socio-economic costs of CRS in the UK. Methods: A case-control study of patients with CRS and healthy controls was conducted to investigate the wider socio-economic impact of the disease. Data on demographic and socioeconomic characteristics, out-of-pocket expenditure (OOPE), health resource utilisation, productivity losses and health-related quality of life (HRQoL) via the EQ-5D and SNOT-22 instruments, were collected from questionnaires. Results: A total of 139 CRS participants and 67 control participants completed the questionnaires. The average total OOPE per patient extrapolated to a 12-month period was £304.84. Other important findings include significantly higher reported primary care interactions (4.14 vs. 1.16) as well as secondary care interactions (2.61 vs 0.4) in CRS group as compared to controls over three-months. The average total missed workdays was estimated to be 18.7 per patient per year. The estimated incremental healthcare cost of CRS per year is £ 16.8 billion or £2.8 billion per million inhabitants. Factors predictive of a higher OOPE include higher household occupancy and income and these accounted for only 9.7% of the total variance in total OOPEs. Other socioeconomic, demographic and HRQoL variables were not found to be predictive factors of OOPE. Conclusions: This study showed that CRS has a significant wider economic burden beyond the immediate direct healthcare costs. CRS participants had a high level of healthcare service use, OOPE and productivity loss. Results from this study will add to the existing limited data both for the UK and abroad and emphasises the need for effective treatments for these patients to reduce the disease impact.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 31904028 Long-term outcomes of different endoscopic sinus surgery in recurrent chronic rhinosinusitis with nasal polyps and asthma 126 135 EN L. Zhang Department of Otolaryngology Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, China; Beijing Key Laboratory of Nasal Diseases, Beijing Institute of Otolaryngology, Beijing, China; Department of Allergy, Beijing TongRen Hospital, Capital Medical University, Beijing, China Y. Zhang Department of Otolaryngology Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, China; Beijing Key Laboratory of Nasal Diseases, Beijing Institute of Otolaryngology, Beijing, China; Department of Allergy, Beijing TongRen Hospital, Capital Medical University, Beijing, China Y. Gao Department of Otolaryngology Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, China K. Wang Department of Otolaryngology Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, China H. Lou Department of Otolaryngology Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, China Y. Meng Department of Otolaryngology Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, China C. Wang Department of Otolaryngology Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, China 2232 10.4193/Rhin19.184 BACKGROUND: Patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and asthma have poorer outcomes after functional endoscopic sinus surgery (FESS) and higher recurrence rate. The aim of present study was to investigate the long-term clinical outcomes of extended surgical strategies for patients with recurrent CRSwNP and asthma. METHODS: Eighty-one patients with CRSwNP and asthma were enrolled in this 5-year prospective study. They were randomly assigned to undergo FESS, radical endoscopic sinus surgery (RESS), or RESS+Draf 3 surgery. Disease severity and clinical outcomes were evaluated using symptoms scoring, endoscopic scoring system, computed tomography staging system, sinus-specific quality of life scores, tissue and peripheral blood eosinophil percentage, and pulmonary function tests. Baseline, 1-year, 3-year, and 5-year follow-up data were compared among the groups. RESULTS: RESS and RESS+Draf 3 strategies yielded better short-term (1 year) outcomes than did FESS. FESS had a higher short-term recurrence rate, although recurrence rates were similarly high (95.6â€"96.1%) in all the groups at 5 years postoperatively. RESS and RESS+Draf 3 yielded a lower long-term revision surgery rate and a longer time to recurrence post-surgery than FESS, which was negatively correlated with tissue and peripheral blood eosinophil percentage. CONCLUSIONS: CRSwNP with asthma is a systemic disease that inevitably recurs. Radical surgery prolongs recurrence time and improves olfaction, rhinorrhea, and quality of life in the short-term. Combining Draf 3 with RESS did not yield better clinical outcomes than RESS alone; thus, although RESS alone appears to be the best option, these findings need to be confirmed in further studies involving more patients, longer follow-up duration and stricter standardized medication use especially the adequate steroid irrigations.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 31904030 Local fungus-specific Immunoglobulin E production in chronic rhinosinusitis with nasal polyps 136 144 EN Y. Ohki Department of Otolaryngology, Head and Neck Surgery, Chiba University Graduate School of Medicine, Chiba, Japan Y. Okamoto Department of Otolaryngology, Head and Neck Surgery, Chiba University Graduate School of Medicine, Chiba, Japan T. Iinuma Department of Otolaryngology, Head and Neck Surgery, Chiba University Graduate School of Medicine, Chiba, Japan H. Yamamoto Division of Otolaryngology, Kimitsu Central Hospital, Kimitsu, Japan T. Toyotome Diagnostic Center for Animal Health and Food Safety, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan M. Yahiro Division of Clinical Research, Medical Mycology Research Center, Chiba University, Chiba, Japan S. Yonekura Department of Otolaryngology, Head and Neck Surgery, Chiba University Graduate School of Medicine, Chiba, Japan D. Sakurai Department of Otolaryngology, Head and Neck Surgery, Chiba University Graduate School of Medicine, Chiba, Japan K. Kamei Division of Clinical Research, Medical Mycology Research Center, Chiba University, Chiba, Japan 2229 10.4193/Rhin18.225 BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a heterogeneous disease, and its pathogenesis remains controversial. This study aimed to examine the involvement of fungi in CRSwNP pathogenesis. METHODS: We enrolled 29 controls and 111 CRSwNP patients. We analyzed fungi in the nasal secretions, serum fungus-specific immunoglobulin E (IgE) levels, and nasal polyp (NP) IgE levels. Moreover, we evaluated the correlation between patients’ IgE levels and computed tomography (CT) scores. RESULTS: There was no difference in fungal detection rate between CRSwNP patients with and without asthma. Specific IgEs against various antigens were highly detectable in NPs of CRSwNP patients. In CRSwNP patients, fungus-specific IgE levels in NPs were correlated with CT scores. Serum fungus-specific IgEs became undetectable after operation in more than half of the CRSwNP patients without asthma but not in those with asthma. Other serum airborne antigen-specific IgEs did not become undetectable after operation. CONCLUSIONS: Fungus-specific IgEs were highly detectable in NPs of CRSwNP patients, and NPs comprised a major region of specific IgE production. Fungi may therefore play an important role in CRSwNP pathogenesis by inducing Th2 immune responses, including IgE synthesis.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 32441707 Role of physical exercise type in olfactory deterioration in ageing 145 150 EN C. Zhang Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, P.R. China D. Li Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, P.R. China X. Wang Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, P.R. China 2358 10.4193/Rhin19.274 BACKGROUND: Although ageing and neurodegenerative diseases, including Alzheimer disease, have been associated with olfaction impairment, studies exploring how to ameliorate this impairment are limited. The aim of the present study was to determine the effect of various types of physical exercise on olfaction decline in ageing. METHODOLOGY: 99 healthy community-dwelling participants (85 women; mean (SD) age, 62.5 (5.7) years) were included. All the participants were required to complete the tests consisting of a questionnaire, cognitive test and olfaction test. RESULTS: Odor identification scores for participants who exercised regularly for more than 1 year (more than 3 times/wk; more than 30 min each time) were significantly higher than those for non-exercisers, and odor detection threshold scores were significantly higher in the exercisers. Both odor threshold and odor identification scores for those who exercised by practicing taiji (tai chi), dancing, or running were significantly better than those for participants who exercised by walking or who did not exercise. CONCLUSION: Compared with those among older people who did not exercise, measures of olfaction among older adults who exercised were better, and the type of physical exercise mattered. Therefore, if physical exercise intervention is suggested to prevent or delay olfactory deterioration in older adults, the type of physical exercise should be considered.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 31799517 A data science-based analysis of seasonal patterns in outpatient presentations due to olfactory dysfunction 151 157 EN J. Lotsch Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany; Fraunhofer Institute of Molecular Biology and Applied Ecology - Project Group Translational Medicine and Pharmacology (IME TMP), Frankfurt am Main, Germany T. Hummel Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany 2196 10.4193/Rhin19.099 BACKGROUND: Changes in human olfactory function throughout the year appear to be a common perception due to the seasonal oscillations in some etiologies associated with olfactory loss. However, longitudinal data from large cohorts were rarely analysed for temporal patterns of human olfaction apart from oscillations in specific etiologies of olfactory loss. METHODS: Temporal patterns in the presentation of patients with olfactory disorders to a single centre were investigated as part of a cohort study. The time series analysis performed utilized a power spectrum analysis and an autoregressive integrated moving average (ARIMA) model in order to demonstrate repetitive fluctuations or trends in the monthly number of patients reporting from January 1999 to December 2017. The analyses additionally addressed temporal changes in the causes to which the olfactory disorder was attributed and in the degree of olfactory loss. RESULTS: A cohort of 7,014 patients was included. Descriptive analysis showed that the presentation of olfactory disorders had seasonal variation, high in March, without a trend. Power spectrum analysis showed a general seasonality of the numbers of patients, without further pattern in the causes or the degree of olfactory dysfunction. CONCLUSIONS: The yearly periodicity in patient presentations at a specialized smell and taste clinic, was not readily attributable to seasonally changing medical causes of olfactory loss such as viral infections. This suggests that in addition to exploring the seasonality of olfactory etiologies, the changes in human olfactory acuity merit further assessments in longitudinal studies.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 31886475 Optimizing DyNaChron instrument for assessing chronic nasal dysfunction symptoms by Rasch analysis 158 165 EN C. Rotonda Universite de Lorraine, APEMAC, equipe MICS, Nancy, F-54000, France M. Soudant CHRU-Nancy, INSERM, Universite de Lorraine, CIC, Epidemiologie Clinique, Nancy, F-54000, France J. Epstein Universite de Lorraine, APEMAC, equipe MICS, Nancy, F-54000, France; CHRU-Nancy, INSERM, Universite de Lorraine, CIC, Epidemiologie Clinique, Nancy, F-54000, France C. Goetz Clinical Research Support Unit, Metz-Thionville Regional Hospital, Metz, F-57000, France R. Jankowski CHRU Nancy, Departement d’Oto-rhino-laryngologie, Nancy, F-54000, France F. Guillemin Universite de Lorraine, APEMAC, equipe MICS, Nancy, F-54000, France; CHRU-Nancy, INSERM, Universite de Lorraine, CIC, Epidemiologie Clinique, Nancy, F-54000, France 2228 10.4193/Rhin19.201 BACKGROUND: The DyNaChron (Dysfonctionnement Nasal Chronique) questionnaire is a self-reporting 78-item instrument assessing six symptoms and their consequences of chronic nasal dysfunction. Patients complete items of a symptom domain only when it is present but in case the patient presents several or all symptoms, its length can limit its use. Here, we aimed to optimize, or shorten, the DyNaChron for clinical use. METHODS: A total of 640 patients in 14 rhinology outpatient clinics all over France completed the original DyNaChron questionnaire before the first rhinologic clinic and 15 days later. The optimization process involved Rasch analysis and then qualitative content analyses. Rasch analysis flagged items with a floor/ceiling effect or with important differential item functioning and an expert committee decided whether to retain the flagged items on the basis of clinical importance and statistical characteristics. The psychometric properties of the optimized version were studied according to classical test theory and Rasch analysis. RESULTS: Rasch analysis revealed 4 items with underfit, 6 with an extreme score, 2 that were highly locally dependent and 16 with differential item functioning which 5 of these 16 items were retained after content analysis. In total, 19 flagged items were removed. Factorial analysis confirmed the preservation of the initial instrument structure in the optimized scale; psychometrics properties and scale calibration were the same as or better than the original version. CONCLUSION: The shortened DyNaChron optimizes the quality of assessment by deleting redundant items and reduces the burden on respondents; the structure is preserved and the psychometrics properties are improved.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 31884512 Predictive significance of Charcot-Leyden Crystal mRNA levels in nasal brushing for nasal polyp recurrence 166 174 EN S. Qi Department of Otolaryngology, Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, P.R. China; Beijing Key Laboratory of Nasal Diseases, Beijing Institute of Otolaryngology, Beijing, P.R. China B. Yan Department of Otolaryngology, Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, P.R. China; Beijing Key Laboratory of Nasal Diseases, Beijing Institute of Otolaryngology, Beijing, P.R. China C. Liu Department of Otolaryngology, Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, P.R. China; Beijing Key Laboratory of Nasal Diseases, Beijing Institute of Otolaryngology, Beijing, P.R. China C. Wang Department of Otolaryngology, Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, P.R. China; Beijing Key Laboratory of Nasal Diseases, Beijing Institute of Otolaryngology, Beijing, P.R. China L. Zhang Department of Otolaryngology, Head and Neck Surgery, Beijing TongRen Hospital, Capital Medical University, Beijing, P.R. China; Beijing Key Laboratory of Nasal Diseases, Beijing Institute of Otolaryngology, Beijing, P.R. China; Department of Allergy, Beijing TongRen Hospital, Capital Medical University, Beijing, P.R. China 2227 10.4193/Rhin19.296 BACKGROUND: Tissue eosinophils have been shown to be associated with polyp recurrence in chronic rhinosinusitis with nasal polyps (CRSwNP). We addressed whether the mRNA levels of Charcot-Leyden Crystal (CLC) in nasal brushing samples, a molecule mainly released from activated eosinophils, could serve as an effective non-invasive biomarker to predict polyp recurrence. METHODS: A total of 51 patients with CRSwNP completing the postoperative follow-up over a period of 12-18 months were enrolled. Baseline CLC mRNA levels of the nasal brushings collected prior to endoscopic sinus surgery were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). Polyp specimens were collected during surgery and were evaluated for inflammatory cells by histopathologic staining. The patients’ baseline characteristics were reviewed and analyzed for associations with recurrence. Logistic regression analysis was performed to determine the predictive factors for polyp recurrence, and receiver operating characteristic (ROC) curves were performed to determine their predictive values. RESULTS: Overall, 25/51(49.02%) patients experienced polyp recurrence during the 12-18 months follow-up. The baseline relative CLC mRNA level in nasal brushing samples was significantly increased in patients with recurrence compared to those without recurrence (p

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 31813944 Deposition of drugs in the nose and sinuses with an exhalation delivery system vs conventional nasal spray or high-volume irrigation in Draf II/III post-surgical anatomy 175 183 EN P.G. Djupesland OptiNose AS, Oslo, Norway J.C. Messina OptiNose US, Inc., Yardley, PA, USA J.N. Palmer University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA 2197 10.4193/Rhin18.304 BACKGROUND: Endoscopic sinus surgery is often performed to improve delivery of topical medication into sinus cavities. Intranasal steroids are guideline recommended in post-surgical patients, and experiments with cadavers suggest that surgery improves delivery of drug into sinuses. Exhalation delivery systems (EDS) use a new mechanism for intranasal delivery and have been shown to reach superior/posterior regions of the nasal cavity better than nasal sprays in unoperated patients. METHODS: Silicone casts of the nasal cavity and sinuses from a patient after Draf II, and then Draf III, were made from high-resolution computed tomography (CT) data using 3D printing. Internal surfaces were coated with liquid-sensitive, color-changing gel. Color changes were evaluated following conventional nasal spray delivery (0.1 mL × 2) (Nasonex®), EDS delivery (0.1 mL × 2) (XHANCE™), and high-volume, low-flow (HVLF) delivery (≈80 mL) with head tilted either 45° or 90°. RESULTS: Conventional nasal spray deposited liquid only in anterior nasal segments. EDS deposited liquid throughout the nasal cavity, in surgically opened ethmoid and maxillary spaces, at entrances of the frontal sinuses in Draf II geometry, and into frontal sinuses in Draf III. Tilted 45°, HVLF delivery enters the maxillary sinuses but not the frontal sinuses or the ethmoid region. At full 90° inclination, HVLF delivery reaches most of the frontal and maxillary sinuses but not the roof and posterior wall of the ethmoid region. CONCLUSIONS: HVLF and EDS produced a deep intranasal/intrasinal deposition in the silicone cast compared with conventional nasal spray delivery; both deposited liquid inside the surgically opened sinuses. HVLF offers the benefit of lavage, whereas EDS may be more efficient and convenient.

International Rhinologic Society Rhinology 0300-0729 58 2 2020 4 1 31693018 Prevalence and risk factors of smell dysfunction - a comparison between five German population-based studies 184 191 EN J. Stogbauer Institute of Epidemiology and Social Medicine, University of Muenster, Germany K. Wirkner LIFE - Leipzig Research Centre for Civilization Diseases, University of Leipzig, Germany C. Engel LIFE - Leipzig Research Centre for Civilization Diseases, University of Leipzig, Germany; Institute for Medical Informatics, Statistics, and Epidemiology (IMISE),University of Leipzig, Germany S. Moebus Centre for Urban Epidemiology, Institute of Medical Informatics, Biometry and Epidemiology, University Hospitals Essen, Germany N. Pundt Centre for Urban Epidemiology, Institute of Medical Informatics, Biometry and Epidemiology, University Hospitals Essen, Germany H. Teismann Institute of Epidemiology and Social Medicine, University of Muenster, Germany M. Loffler LIFE - Leipzig Research Centre for Civilization Diseases, University of Leipzig, Germany; Institute for Medical Informatics, Statistics, and Epidemiology (IMISE),University of Leipzig, Germany T. Hummel Clinic of Otorhinolaryngology, University Hospital Dresden, University of Dresden, Germany A.G. Beule Clinic of Otorhinolaryngology, University Hospital Muenster, University of Muenster, Germany; Department of Otorhinolaryngology, University Clinic Greifswald, University of Greifswald, Germany K. Berger Institute of Epidemiology and Social Medicine, University of Muenster, Germany 2194 10.4193/Rhin19.181 BACKGROUND: The prevalence of olfactory impairment increases with age and is known to be an early sign of different neurodegenerative diseases. Only few population-based studies examined the prevalence of olfactory impairment and comparisons across studies are scarce. Aim of this analysis was to compare the prevalence and determinants of normosmia across five population based studies in Germany. METHODOLOGY: Data from five population-based, cross-sectional studies were included. They were independently conducted and used the same test system (Sniffin’ Sticks Screening 12) to measure olfactory function. This system consists of 12 odor-dispensing felt-tip pens; the task is a forced-choice selection among four alternative odors per pen. Sociodemographic information and comorbidities were assessed in face-to-face interviews. Univariate, descriptive statistics and multivariable logistic regression models stratified by study, were performed to determine risks, i.e. prevalence odds ratios, associated with olfactory function. RESULTS: The prevalence of normosmic participants varied considerably across studies. Olfactory function was lower in men, decreased with age, and increased with higher education. Several individual comorbidities and a comorbidity index were associated with olfactory dysfunction. Recognition performance for three of the 12 pens was especially low in all studies. CONCLUSION: Four factors, well known to describe population composition, contribute to explain differences in the prevalence of olfactory function between studies when the same test system is used. Our results indicate that comorbidities and educational level should always be considered when test systems based on smell recognition are used in population-based studies.