High prevalence of olfactory impairment among leprosy patients: A cross-sectional study

BackgroundThe effect of leprosy on the sense of smell is not yet fully established. Studies that have relied only on patients' perceptions may have under- or over-estimated the change in smell perception. A validated and psychophysical method is necessary to avoid these errors in assessment. ObjectivesThis study aimed to validate the existence of olfactory involvement in leprosy patients. MethodsA cross-sectional, controlled study was conducted, in which individuals with leprosy (exposed individuals) and individuals without leprosy (control patients) were recruited. For each exposed individual, we selected two control patients. A total of 108 patients (72 control patients and 36 exposed individuals) with no history of infection with the new coronavirus (COVID-19) took the University of Pennsylvania Smell Identification Test (UPSIT). ResultsMost exposed individuals had olfactory dysfunction [n = 33, 91.7% (CI 95%: 77.5%-98.3%)] when compared with the control patients [n = 28, 38.9% (CI 95%: 27.6%-51.1%)], but only two (5.6%) had olfactory complaints. The olfactory function was significantly worse among exposed individuals [UPSIT leprosy = 25.2 (CI 95%: 23.1-27.3) when compared with the UPSIT control patients = 34.1 (CI 95%: 33.0-35.3); p<0.001]. The risk of olfactory loss was higher among the exposed individuals [OR: 19.5 (CI 95%: 5.18-105.70; p < 0.001)]. ConclusionsOlfactory dysfunction was highly prevalent among exposed individuals, although they had little or no self-knowledge of the disorder. The results show that it is important to assess the sense of smell in exposed individuals. Author summaryLeprosy is one of the oldest neurocutaneous diseases in the world. However, it has been neglected by the general population, doctors, and scientists. Transmitted by Mycobacterium leprae and Mycobacterium lepromatosis, leprosy is met with stigma and prejudice. Some patients with leprosy (exposed individuals) keep their diagnosis a secret, fearing a negative impact on their social lives. The disease is characterized by white or red skin lesions associated with local numbness. Few studies have evaluated smell among exposed individuals, but they have not used the University of Pennsylvania Smell Identification Test (UPSIT), which is a validated psychophysical method. The present study found a high prevalence of olfactory impairment (91.7%) among exposed individuals, accompanied by low self-knowledge of the disorder (5.6%). It is thus important to assess the sense of smell in infected individuals, as this sensorineural assessment has not been performed as a routine for patients.