The predictive value of SS-16 in clinically diagnosed Parkinson’s disease patients:comparison with ^(99m)Tc-TRODAT-1 SPECT scans

Background:Dopamine transporter based imaging has high diagnostic performance in distinguishing patients with Parkinson’s disease(PD)from patients with non-Parkinsonian syndromes.Our previous study indicated that the“Sniffin’Sticks”odor identification test(SS-16)acts as a valid instrument for olfactory assessment in Chinese PD patients.The aim of the study was to compare the efficacy of the two methods in diagnosing PD.Methods:Fifty-two PD patients were involved in this study and underwent single photon emission computed tomography(SPECT)imaging using the labeled dopamine transporter radiotracer ^(99)mTc-TRODAT-1 to assess nigrostriatal dopaminergic function.Olfactory function was assessed with the“Sniffin’Sticks”odor identification test(SS-16)in all patients who received DAT-SPECT scanning.Statistical analysis(SPSS version 21)was carried out to determine the diagnostic accuracy of SS-16 as well as its correlation with ^(99)mTc-TRODAT-1 SPECT,its positive predictive value(PPV),and negative predictive value(NPV).Results:We identified a negative correlation between SS-16 and DAT SPECT(Kappa=0.269,p=0.004).By using the ^(99)mTc-TRODAT-1 uptake results as the gold standard,the sensitivity and specificity of SS-16 was 56.8 and 37.5%,respectively.Furthermore,the negative and positive predictive values were calculated as 13.6 and 83.3%,respectively.Conclusions:SS-16 would not be used as a diagnostic tool for early stage PD patients.Negative results of SS-16 would not exclude the diagnosis of PD.Further tests are needed for validation.