title: Predictive power of Koplik's spots for the diagnosis of measles.
abstract: BACKGROUND
  Measles is a major cause of mortality globally. In many countries, management of measles is based on clinical suspicion, but the predictive value of clinical diagnosis depends on knowledge and population prevalence of measles. In the pre-vaccine era with high measles incidence, Koplik's spots (KS) were said to be "pathognomonic". This study prospectively evaluated test properties and diagnostic odds ratios (OR) of KS.
  
  
  METHODS
  Data including KS status were prospectively collected for a six-month period on all suspected measles cases reported to the North-West London Health Protection Unit. Saliva test kits were sent to all cases and KS test properties were analysed against measles confirmation by PCR or IgM testing (gold standard).
  
  
  RESULTS
  The positive predictive value (PPV) of clinically suspecting measles was 50%. Using KS as diagnostic tool improved the PPV to 80% and the presence of KS was associated with confirmed measles in the multi-variable analysis (OR 7.2, 95% Confidence Interval 2.1-24.9, p=0.001).
  
  
  CONCLUSIONS
  We found that Koplik's spots were highly predictive of confirmed measles and could be a good clinical tool to enable prompt measles management and control measures, as action often needs to be taken in the absence of laboratory confirmation. We suggest that current clinical case definitions might benefit from the inclusion of KS.
authors.affiliation: Centre for Infection, HPA, London UK. dominik.zenner@hpa.org.uk
authors.forename: Dominik
authors.initials: D
authors.lastname: Zenner
authors.forename: Luis
authors.initials: L
authors.lastname: Nacul
mesh_terms: D005076:Exanthema / Q000473:pathology*; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D008131:London / Q000453:epidemiology; D008457:Measles / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology / Q000821:virology; D008459:Measles virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D009061:Mouth Mucosa / Q000473:pathology*; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D012463:Saliva / Q000821:virology; D012680:Sensitivity and Specificity
chemical_list: D007075:Immunoglobulin M