title: A comparison of Bayesian and maximum likelihood methods to determine the performance of a point of care test for Helicobacter pylori in the office setting.
abstract: OBJECTIVE
  Evaluations of point of care tests (PCT) are often hampered by a lack of appropriate gold standards. This study aimed to compare the results of a Bayesian statistical analysis and a maximum likelihood method to evaluate the performance of a PCT for Helicobacter pylori in primary care.
  
  
  METHODS
  The Helisal Rapid Blood Test (Cortecs Diagnostics) was performed in 311 patients from 6 primary care centers, and a concurrent venous sample was taken for 2 enzyme-linked immunosorbent assays (ELISA) performed at the laboratory, blind to the PCT result. The Bayesian analysis was conducted using Markov Chain Monte Carlo methods (WinBUGS). The performance characteristics of the PCT and the 2 ELISA tests were estimated together with 95% credible intervals (95% CIs).
  
  
  RESULTS
  The estimate of prevalence of H. pylori in this population was 64% (95% CI, 59% to 70%), the sensitivity and specificity of the PCT were 89% (84% to 94%) and 84% (77% to 91%), respectively (likelihood ratios positive 5.6, negative 0.13). The equivalent maximum likelihood results were prevalence, 65%; sensitivity, 90%; and specificity, 83%.
  
  
  CONCLUSIONS
  The Helisal Rapid Blood Test performed as well as laboratory-based ELISA tests in this cohort of patients. The Bayesian analysis and the maximum likelihood method gave similar results, the Bayesian method also simultaneously estimating 95% CIs.
authors.affiliation: Department of Primary Care and General Practice, Medical School, University of Birmingham, Edgbaston, United Kingdom. b.c.delaney@bham.ac.uk
authors.forename: Brendan C
authors.initials: BC
authors.lastname: Delaney
authors.forename: Roger L
authors.initials: RL
authors.lastname: Holder
authors.forename: Teresa F
authors.initials: TF
authors.lastname: Allan
authors.forename: Joyce E
authors.initials: JE
authors.lastname: Kenkre
authors.forename: F D Richard
authors.initials: FD
authors.lastname: Hobbs
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001499:Bayes Theorem; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016481:Helicobacter Infections / Q000097:blood / Q000175:diagnosis*; D016480:Helicobacter pylori / Q000276:immunology / Q000302:isolation & purification; D006403:Hematologic Tests; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems / Q000592:standards* / Q000706:statistics & numerical data; D011320:Primary Health Care / Q000379:methods / Q000592:standards*; D012015:Reference Standards; D012680:Sensitivity and Specificity