Low specificity and sensitivity of smell identification testing for the diagnosis of Parkinson?s disease

Abstract

Objective: The aim of this study is to determine if the University of Pennsylvania's Smell Identification Test (UPSIT) is an accurate diagnostic tool for olfactory dysfunction in Parkinson's disease (PD). Method: We included 138 non-demented PD subjects and 175 control subjects matched by gender. Smell identification was tested using UPSIT. Results: The mean number of UPSIT items correctly identified by controls was 27.52±5.88; the mean score for PD subjects was 19.66±6.08 (p=<0.001). UPSIT sensitivity was 79.7% with a specificity of 68.5% using a cut-off score of ≤25. The overall accuracy for the diagnosis of PD was of 75.3%. Conclusion: UPSIT accuracy and specificity were lower than what has been previously reported. Our data demonstrates that 17.5% of items of the UPSIT were not well identified by healthy controls. Further research of the identification of a truly cross-cultural test is warranted.Keywords: Parkinson's disease, University of Pennsylvania Smell Identification Test, olfaction, diagnostic test. resumo Objetivo: O objetivo deste estudo é determinar se o University of Pennsylvania Smell Identification Test (UPSIT) é uma ferramenta diagnóstica útil para a caracterizar disfunção olfativa na doença de Parkinson (DP). Método: Foram incluídos 138 indivíduos não dementes assuntos PD e 175 indivíduos controle pareados por sexo. Identificação cheiro foi testada usando UPSIT. Resultados: O número médio de itens UPSIT corretamente identificados pelos controles foi de 27,52±5,88; para sujeitos com DP foi de 19,66±6,08 (p=<0,001). A sensibilidade do UPSIT foi de 79,7%, com especificidade de 68,5%, utilizando um ponto de corte de ≤25. A exatidão global para o diagnóstico de DP foi de 75,3%. Conclusão: A precisão e a especificidade do UPSIT foram menores do que o que foi relatado anteriormente. Nossos dados demonstram que 17,5% dos itens da UPSIT não foram adequadamente identificados pelos controles saudáveis. São necessárias outras pesquisas para a identificação de um teste verdadeiramente cross-cultural nessa área.Palavras-chave: doença de Parkinson, University of Pennsylvania Smell Identification Test, olfato, teste de diagnostic.

Diagnostic Accuracy, Item Analysis and Age Effects of the UPSIT Spanish Version in Parkinson’s Disease

“…In our sample, the optimal cut-off score was identified as ≤25, with a diagnostic accuracy of 82.7%, a sensitivity of 81.4%, and a specificity of 84.6%. This observed sensitivity is similar to that found in a Mexican population using the same cut-off score (Rodriguez-Violante, Gonzalez-Latapi, Camacho-Ordonez, et al, 2014a, 2014b. In an Italian study, the cut-off score of ≤21 differentiated PD and HC with similar sensitivity (82.0%) and specificity (88.2%) (Picillo et al, 2014).…”

“…We performed an item analysis similar to previous works (Kondo, Matsuda, Hashiba, 1998;Picillo et al, 2014;Rodriguez-Violante, Gonzalez-Latapi, Camacho-Ordonez, et al, 2014b;Silveira-Moriyama et al, 2008). Our results showed that some items had a rate of correct answers of less than 50.0% in HC (cedar, lemon, cherry, dill pickle and walnut), specifically, the three age groups coincided on dill pickle and walnut.…”

“…Furthermore, previous works found a decreased identification of some UPSIT items in healthy populations (Picillo et al, 2014;Silveira-Moriyama et al, 2008;Rodriguez-Violante, Gonzalez-Latapi, Camacho-Ordonez, et al, 2014b;Kondo, Matsuda, Hashiba, 1998). In this sense, the analysis of individual smell scores of UPSIT Spanish version may allow identifying items with greater accuracy in PD diagnosis, and items that are culturally unsuitable.…”

Diagnosis and Management of Parkinson's Disease

“…47,48 Its utility as a diagnostic tool, however, is limited due to the low sensitivity and specificity of testing. 49 Pain is a frequent complaint among patients with PD, with one study estimating the prevalence at 83%. 28,50 Rapid eye-movement (REM) sleep behavior disorder, manifested by acting out dreams with a loss of normal atonia during REM sleep, can also predate the onset of motor symptoms by many years, or occur at any point during the disease.…”

Improved diagnosis of Parkinson's disease from a detailed olfactory phenotype

“…Such testing is critical for assessing olfactory dysfunction, since self‐report can be unreliable 10. However, the only information typically retained from an UPSIT test – the total score – may be a crude measure for guiding diagnosis; while the mean total score of the PD subpopulation is lower than in healthy subjects,9 the sensitivity and specificity of the total score in distinguishing PD from non‐PD‐related olfactory deficits may not be high enough, or early enough in disease progression, to be clinically valuable 11. But what if the pattern of olfactory decline due to PD differs from that due to other age‐related pathologies or to normal aging?…”