title: Influence of random answers on interpretation of the Sniffin' Stick identification test in nasal polyposis.
abstract: OBJECTIVE
  The Sniffin' Stick identification subtest, a validated tool to evaluate the sense of smell, is based on the recognition of 16 different odours. The patient is required to choose an answer from among four proposed odours, which introduces the possibility of obtaining random correct answers, especially in patients with an altered sense of smell. This study was designed to evaluate the influence of these random correct answers on interpretation of the simplified version of the Sniffin' Stick test comprising threshold and identification tests in patients with nasal polyposis.
  
  
  METHODS
  Forty-two consecutive patients with nasal polyposis operated according to the nasalization procedure were enrolled in this prospective study. Odour threshold and identification tests of the Sniffin' Stick kit were performed before and 1 month after surgery. Random correct answers on the identification (I) test (IH) were subtracted from the global number of correct answers (IG) to calculate a real identification score (IR), corresponding to the number of correct answers unrelated to chance.
  
  
  RESULTS
  Two groups of patients were identified: one group with no random correct answers (IH0) (n=17) and another group giving 1 to 7 random correct answers (IH1-7) (n=25). In the IH1-7 group, significantly more patients had an immeasurable threshold (T=0) than a measurable threshold (21 versus 4, P=0.0001). In this subgroup of 21 patients [IH1-7, T=0], the mean IR score was significantly lower than the mean IG score (P<0.0001) and 13 patients were classified as [IR=0; T=0]. Among these 13 patients classified as severe anosmia [IR=0; T=0] preoperatively, only 3 remained severe anosmic [IR=0; T=0] postoperatively.
  
  
  CONCLUSIONS
  Random answers to the I identification test were more numerous among patients unable to detect n-Butanol on the T threshold test than among patients able to detect n-butanol. Calculation of the IR identification score allows more precise interpretation of the results of the identification test in patients with severe anosmia.
authors.affiliation: Service d'ORL et de chirurgie cervico-faciale, hôpital central, CHU de Nancy, 29, avenue du Maréchal-de-Lattre-de-Tassigny, 54000 Nancy, France. Electronic address: helene.eluecque@yahoo.fr.
authors.forename: H
authors.initials: H
authors.lastname: Eluecque
authors.affiliation: Service d'ORL et de chirurgie cervico-faciale, hôpital central, CHU de Nancy, 29, avenue du Maréchal-de-Lattre-de-Tassigny, 54000 Nancy, France; Inserm CIC-EC CIE6, 9, avenue de la Forêt-de-Haye, 54505 Vandœuvre-Lès-Nancy, France.
authors.forename: D T
authors.initials: DT
authors.lastname: Nguyen
authors.affiliation: Service d'ORL et de chirurgie cervico-faciale, hôpital central, CHU de Nancy, 29, avenue du Maréchal-de-Lattre-de-Tassigny, 54000 Nancy, France.
authors.forename: R
authors.initials: R
authors.lastname: Jankowski
mesh_terms: D000328:Adult; D000368:Aged; D003955:Diagnostic Tests, Routine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009298:Nasal Polyps / Q000150:complications*; D000857:Olfaction Disorders / Q000175:diagnosis* / Q000209:etiology*; D011446:Prospective Studies; D012684:Sensory Thresholds; D012903:Smell
keywords: Chance; Identification test; Nasal polyposis; Sniffin Stick; Threshold test