Agreement of Rapid Test Screening and RT-PCR for Influenza in Suspected Cases of Avian Influenza
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Date
2007-02-02
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Buddhachinaraj Medical Journal
Abstract
PROBLEM/BACKGROUND: The avian influenza (H5N1) virus is an emerging virus that causes many human fatalities and poses an increasing pandemic threat. A surveillance system is an important part of the disease control of the pandemic influenza strategy. The initial screening guideline includes clinical manifestations, history of exposure and rapid test.OBJECTIVE: To determine the agreement of rapid test and RT-PCR for influenza in suspected cases of avian influenza, and final diagnosis of these cases.RESEARCH DESIGN: Diagnostic test study.SETTING: Budhacinnaraj Phitsanulok Hospital.MATERIALS and METHODS: A retrospective study of medical records of 137 consecutive patients presented to Budhachinnaraj Hospital screening scheme for avian influenza from Jan, 2005 to Dec, 2006. The rapid test was chosen to be the screening test. RT-PCR for influenza was performed as a confirmatory test. Statistical analysis was done using Kappa test, chi-square test, and Fisherís exact test; presented by sensitivity, specificity, positive predictive value and Kappa coefficient.RESULTS: The most common final diagnosis of suspected cases were non-specific URI (47.8%), followed by human influenza A (22.6%). With respect to clinical manifestations, history of fever and upper respiratory tract symptoms were the most common findings (92 % and 91.2 % respectively). The rapid test was performed in all suspected cases. RT-PCR for influenza was pursued in cases with high index of suspicious (72.3%), with 31.3% positive result. Sensitivity of rapid test compared to RT-PCR was unacceptable low (41.9%). Kappa coefficient was 0.476 (p \< 0.001).CONCLUSIONS: There is no avian influenza identified in our hospital during the study period. Human influenza were identified 22.6% of the suspected cases of avian influenza. Accuracy of rapid test from nasopharyngeal swab was found to be very low which raise awareness of interpretation of the test. The efficacy of the agreement of these two tests is medium.
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Buddhachinaraj Medical Journal; Vol.24 No.2 May-August 2007; 165-174