Non allergic rhinitis: Prevalence, clinical profile and knowledge gaps in literature

Objectives: Although Nasal symptoms induced by Non-allergic rhinitis' (NAR) are a cause of wide spread morbidity; the disease is trivialized. There is a lack of Epidemiological studies on the prevalence of non-allergic rhinitis. In spite of being one of the commonest conditions presenting to the General practitioner and otolaryngologists, the clinical profile, diagnosis, and management outcomes are unknown. The objectives of the study were to examine the prevalence and clinical profile of non-allergic rhinitis in Oman. Secondary objective was to identify Knowledge gaps in literature with the aim of directing future research. Methods: A cross sectional study of 610 consecutive adult patients presenting to the Ear, Nose and Throat clinic at Sultan Qaboos University Hospital is presented in this paper. The diagnosis of NAR was mainly based on step wise fashion; including a thorough clinical history and exclusion of other causes of rhinitis; all consecutive patients diagnosed with rhinitis (n=113) had a detailed history, nasal endoscopy, nasal smears, CT scans and an antihistamine response trial. The prevalence of NAR with its clinical profile was subsequently determined. Primary research articles and meta-analysis evaluated for the knowledge gap study were identified through MEDLINE search of English language literature published between 2000-2011. Results: A total of 610 consecutive patients were studied. The overall prevalence of rhinitis was 18.5% (n=113). The prevalence of NAR was 7.5% (n=46). Cases of allergic rhinitis (5.7%; n=35), Chronic rhinosinusitis (1.8%; n=11), and miscellaneous causes (3.4%; n=21) were excluded. Among the rhinitis population (n=113), the prevalence of NAR was 57% (n=46). The major presenting symptoms included nasal obstruction (93%; n=43), postnasal drainage (78%; n=36), and rhinorrhea (62%; n=29). For the knowledge gap study; 115 Medline titles were reviewed, four systematic reviews, and 34 research papers were reviewed. The text of two recent otolaryngology text books was also reviewed, and the main results of the study revealed the prevalence of NAR had not previously been studied in Oman. Although the recent text now clearly defines NAR, there is scant literature on the prevalence, diagnosis and management outcomes of NAR in the literature. Conclusion: The study found that more than half of rhinitis patients suffered from NAR. There are no specific diagnostic tests for NAR; a thorough case history is the best diagnostic tool to date. A substantial knowledge gap exists in literature with relations to pathogenesis, clinical and laboratory diagnosis, as well as in reference to medical and surgical outcomes. Larger studies are required and management outcomes need to be studied.