Validation of the utility of the Brief Smell Identification Test in Chinese patients with Parkinson’s disease

Hyposmia is a common non-motor symptom occurring in Parkinson's disease (PD), and has been included in the diagnostic criteria. Although a version of the Brief Smell Identification Test (B-SIT) has been developed specifically for Chinese populations, there have been no reports of the utility of this test in the diagnosis of PD in China.Considering the influence of cultural factors on olfactory test findings, we sought to investigate the utility and efficiency of the B-SIT in Chinese PD patients.PD patients were recruited from the Movement Disorder Clinic of Xuanwu Hospital, and healthy controls were recruited from the Beijing Longitudinal Study on Aging Cohort II, between 2015 and 2016. The B-SIT was used for olfactory function testing in all subjects, and the familiarity of 59 odors questionnaire was performed for the investigation of familiarity of odors.A sample of 275 subjects participated in the study, including 112 healthy controls and 163 PD patients. The sensitivity (64.1%), specificity (83.9%), positive predictive value (83.5%) and negative predictive value (64.8%) for identifying PD were measured with the B-SIT. The consistency values between the results of self-reported smell loss and hyposmia identified by B-SIT in control and PD groups were 74.8% and 64.2%, respectively. Most of the odors in the B-SIT were familiar to people in the Chinese population, based on a survey of 3356 subjects using a familiarity questionnaire.It is recommended to use the B-SIT olfactory test instead of self-reported smell loss for PD diagnosis for Chinese.