Conventional blood tests in predicting influenza A (H1N1) rapidly

Abstract

Purpose. Although real-time reverse transcriptase-polymerase chain reactions (rRT-PCR) are gold standard for the diagnosis of influenza A (H1N1), the results can be delayed up to several days, which is problematic during a pandemic. Because of this limitation of rRT-PCR, clinicians have often had to set a treatment plan that was solely based on clinical suspicion. We investigated the hematological and biochemical factors that are associated with rRT-PCR results, in order to help clinicians deal with acute febrile patients during influenza pandemics. Methods. We conducted a retrospective, cross-sectional study of 465 emergency department patients who underwent both rRT-PCR and blood tests at the same time. Hematological and biochemical findings were compared between the rRT-PCR-positive group and rRT-PCR-negative group. Results. Levels of leukocytes, hemoglobin, platelets, blood urea nitrogen (BUN), total bilirubin, lactate dehydrogenase, serum glucose, C-reactive protein (CRP), and procalcitonin were significantly different between the two groups in the univariate analyses. In the multivariate analyses, leukocyte counts ≤ 10.8 (× 10⁹)/L [odd ratio (OR) = 8.2, sensitivity = 93.7%, NPV = 85.3%], BUN levels ≤ 7.1 μmol/L (OR = 3.0, sensitivity = 93.7%, NPV = 85.3%), and CRP levels ≤ 60 mg/L (OR = 2.4, sensitivity = 93.7%, NPV = 85.3%) were independently associated with positive rRT-PCR results. Conclusions. Leukocyte counts, BUN levels and CRP levels were important predictors of rRT-PCR-positive results for 2009 influenza A (H1N1) in adults.

Key Words::

• Influenza A virus
• diagnosis
• respiratory tract infections
• hematologic tests
• reverse transcriptase polymerase chain reaction

Acknowledgements

The authors thank Dr Dong Hyun Sinn and Ms Mi Yeon Lee for their advice and contribution to this study.

Declaration of interest: The authors have no conflicts of interest. The authors alone are responsible for the content and writing of the paper.