Evaluation of Diagnostic Performance of a Polymerase Chain Reaction for Detection of Canine Dirofilaria immitis

초록

Diagnostic performance of polymerase chain reaction (PCR) for detecting Dirofilaria immitis in dogs wasevaluated when no gold standard test was employed. An enzyme-linked immunosorbent assay test kit (SnapTM, IDEXX,USA) with unknown parameters was also employed. The sensitivity and specificity of the PCR from two-populationmodel were estimated by using both maximum likelihood using expectation-maximization (EM) algorithm and Bayesianmethod, assuming conditional independence between the two tests. A total of 266 samples, 133 samples in each trial,were randomly retrieved from the heartworm database records during the year 2002-2004 in a university animal hospital.for heartworm infection. When combined 2 trials, sensitivity and specificity of the PCR was 96.4-96.7% and 97.6-98.8%in EM and 94.4-94.8% and 97.1-98% in Bayesian. There were no statistical diferences between estimates. This findingindicates that the PCR assay could be useful screening tool for detecting heartworm antigen in dogs. This study wasprovided further evidences that Bayesian approach is an alternative approach to draw better inference about theperformance of a new diagnostic test in case when either gold test is not available.

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