Characteristics of Smell Identification Test in Patients With Parkinson Disease

OBJECTIVES

Parkinson disease (PD) is frequently associated with olfactory disorder at early stage, which is caused by deposition of Lewy bodies emerging from the olfactory bulb to higher olfactory centers. Early detection of olfactory disorder in the patients with PD may lead to the early diagnosis and treatment for this refractory disease.

METHODS

Visual analog scale (VAS), Jet Stream Olfactometry, and Japanese smell identification test, Open Essence (OE), were carried out on 39 patients with PD. Thirty-one patients with postviral olfactory disorder (PVOD), which was caused by the olfactory mucosal dysfunction, were also enrolled in this study as control.

RESULTS

There were no significant differences in detection thresholds (2.2 vs. 1.4, P=0.13), recognition thresholds (3.9 vs. 3.5, P=0.39) and OE (4.8 vs. 4.2, P=0.47) between PVOD and PD, while VAS scores of PVOD and PD were significantly different (2.0 and 6.2, P<0.01). In OE, significant differences were observed in the accuracy rates of menthol (68% vs. 44%, P=0.04) and Indian ink (42% vs. 15%, P=0.01) between PVOD and PD. Of particular interest, patients with PVOD tended to select "no detectable," while patients with PD tended to select wrong alternative other than "no smell detected."

CONCLUSION

Discrepancy between VAS and OE, and high selected rates of wrong alternative other than "undetectable" in OE might be significant signs of olfactory dysfunction associated with PD.

Sensitivity analysis and diagnostic accuracy of the Brief Smell Identification Test in patients with chronic rhinosinusitis

BACKGROUND

The Brief Smell Identification Test (BSIT) is an abbreviated version of the Smell Identification Test (SIT) used to assess olfactory function. Although the BSIT can be efficiently administered in under 5 minutes, the accuracy of the BSIT in relation to the SIT in patients with chronic rhinosinusitis (CRS) is unknown.

METHODS

Patients with CRS were recruited as part of an ongoing multi-institutional observational cohort study. A total of 183 participants provided both BSIT and SIT olfactory function scores during initial enrollment. Linear associations between BSIT and SIT scores were evaluated using Pearson's correlation coefficients (rp ). The sensitivity, specificity, and accuracy of BSIT scores were determined using SIT scores as the "gold standard."

RESULTS

A strong bivariate linear association was found between BSIT and SIT scores (rp = 0.893; p < 0.001) for all participants. A significantly lower proportion of patients were identified as having abnormal olfaction using the BSIT compared to the SIT (47% vs 68%, respectively; p < 0.001). Using the currently defined score of ≤8 as a cut-point for abnormal olfactory function, the BSIT demonstrated a sensitivity of 63% and specificity of 88% with an overall accuracy of 71%. Increasing the cut-point to ≤9 resulted in an increased sensitivity of 86%, a specificity of 76%, and an improved overall accuracy of 83%.

CONCLUSION

In patients with CRS, BSIT scores strongly correlate with SIT scores; however, the BSIT underestimates olfactory dysfunction as defined by the suggested cut-point of ≤8. Increasing the cut-point to ≤9 increased the sensitivity and accuracy of the BSIT.