title: Predictors for benign paroxysmal positional vertigo with positive Dix-Hallpike test.
abstract: OBJECTIVE
  Patient medical history is important for making a diagnosis of causes of dizziness, but there have been no studies on the diagnostic value of individual items in the history. This study was performed to identify and validate useful questions for suspecting a diagnosis of benign paroxysmal positional vertigo (BPPV).
  
  
  METHODS
  Construction and validation of a disease prediction model was performed at the outpatient clinic in the Department of General Medicine of Chiba University Hospital. Patients with dizziness were enrolled (145 patients for construction of the disease prediction model and 61 patients for its validation). This study targeted BPPV of the posterior semicircular canals only with a positive Dix-Hallpike test (DHT + BPPV) to avoid diagnostic ambiguity. Binomial logistic regression analysis was performed to identify the items that were useful for diagnosis or exclusion of DHT + BPPV.
  
  
  RESULTS
  Twelve patients from the derivation set and six patients from the validation set had DHT + BPPV. Binomial logistic regression analysis selected a "duration of dizziness ≤15 seconds" and "onset when turning over in bed" as independent predictors of DHT + BPPV with an odds ratio (95% confidence interval) of 4.36 (1.18-16.19) and 10.17 (2.49-41.63), respectively. Affirmative answers to both questions yielded a likelihood ratio of 6.81 (5.11-9.10) for diagnosis of DHT + BPPV, while negative answers to both had a likelihood ratio of 0.19 (0.08-0.47).
  
  
  CONCLUSIONS
  A "duration of dizziness ≤15 seconds" and "onset when turning over in bed" were the two most important questions among various historical features of BPPV.
authors.affiliation: Department of General Medicine, Chiba University Hospital, Chiba, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Noda
authors.forename: Masatomi
authors.initials: M
authors.lastname: Ikusaka
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ohira
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Takada
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tsukamoto