Validation of a new olfactory test for Chinese Parkinson's disease patients

Hyposmia is a common non-motor symptom in Parkinson's disease (PD) and has been used to assist PD diagnosis and early screening of prodromal patients. Although the Brief Smell Identification Test (B-SIT) is the most commonly used olfactory test, its utility was limited by the culture difference in recognition of the smells included in the test. We have developed a new modified B-SIT test for Chinese (B-SITC), and validated and compare it with B-SIT in Chinese PD patients.

From 2015 to 2018, 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. The two olfactory tests were used in healthy volunteers and PD patients.

A total of 428 subjects participated in the study: 211 healthy controls and 217 PD patients. The average B-SIT and B-SITC scores were significantly different between control and PD groups (B-SIT, 9.18 ± 1.94 vs. 6.90 ± 2.44, P = 0.0001; B-SITC, 8.60 ± 1.93 vs. 5.91 ± 2.21, P = 0.0001). The B-SITC had good sensitivity (73.1%), specificity (76.8%), positive predictive value (76.8%), and negative predictive value (73.1%) for the diagnosis of Chinese PD, and the area under the curve (AUC) value was greater for the B-SITC than for the B-SIT (0.838 vs. 0.761).

The B-SITC is useful for the clinical assessment of olfactory function in Chinese PD patients.