Assessing olfactory function in patients with smell disorders in the South Kivu province of the Democratic Republic of Congo

Objective: Olfactory disorders may be associated with different etiologies, including upper respiratory infections, sinonasal conditions, head injuries, exposure to toxins, and congenital anosmia. This study aimed to evaluate the prevalence of different etiologies for olfactory dysfunction as observed in a sub-Saharan African population. Methods: This descriptive cross-sectional study was conducted in a series of 116 consecutive patients with an olfactory disorder who lived in the city of Bukavu in the South Kivu province of the Democratic Republic of the Congo. The study was conducted from June 1, 2016 to May 30, 2017. We used the Sniffin’ Sticks test, adapting the identification (I) test to our population but retaining the standard threshold (T) and discrimination (D) tests. The patients were classed as anosmic if their composite T + D + I score was 30. Informed consent was obtained in accordance with the Declaration of Helsinki II. We calculated proportions for each olfactory disorder. Results: Median age (minimum–maximum) in our 116 patients was 42.5 (18–83) years. Women made up 60% of our sample. It was observed that 70.7% of patients had anosmia and 29.3% hyposmia. In descending order, the main causes were upper respiratory infections (49.1%), congenital causes (34.5%), nasal polyps (6%), nose and/or sinus surgery (3.4%), head injuries (2.6%), metabolic causes (2.6%), and occupational exposure to toxins (1.7%). Hyposmia predominated when the cause was upper respiratory infection, whereas anosmia did when the cause was congenital and noninfectious. Conclusion: In our study population, upper respiratory infections were the main cause of dysosmia. The anosmic cases we observed tended to be congenital in nature, suggesting that there existed other etiological factors that require further investigation