Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Prattes, J.
Comparison of demographic data, clinical presentation, risk factors and outcome between PCR confirmed H1N1 influenza and PCR negative influenza-like illnesses
[ Diplomarbeit ] Medical University of Graz; 2013. pp. 82
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- Autor*innen der Med Uni Graz:
- Prattes Jürgen
- Betreuer*innen:
- Hönigl Martin
- Krause Robert
- Altmetrics:
- Abstract:
- Aim: One of the major influenza A H1N1 diagnostic problems is the poor sensitivity of currently available rapid influenza antigen tests (RIATs) for H1N1 influenza detection, and the inability to differentiate with RIATs between H1N1 and other influenza A strains. On the other hand, PCR, the gold standard for H1N1 influenza diagnosis and confirmation, has a long turn-around time and is also expensive. Timely diagnosis is important, however, as antiviral therapy - if started within 48 hours after infection - may reduce duration of hospitalization as well as the duration of illness, and lowers the risk of intensive care unit (ICU) admission. For these reasons, it seems to be important to understand the differences in first clinical presentation between PCR confirmed influenza and influenza-like illnesses (ILI), in order to improve the outcome and reduce health care costs. Methods: We included 1681 patients with PCR confirmed H1N1 or influenza-like illness (ILI=suspicions of influenza but negative PCR for H1N1 and other influenza strains) during October 2009 to January 2010. Complete data sets were available for 209/624 (31%) patients with PCR confirmed H1N1 and for 310/1057 (30%) patients with Influenza like illnesses. We compared patients with H1N1 and ILI with respect to demographic data, clinical presentation, treatment, outcome and preexisting underlying illnesses, using Fischer¿s exact test and independent samples t-tes Results: The mean age in the H1N1 influenza group was 23.88 years (95% CI 20.95-26.8) versus 32.88 years in the ILI group (95% CI 29.92-35.85) (p<0.001). The mean time from onset of symptoms to first clinical presentation was lower in the H1N1 influenza group compared to the ILI group [1.78 days (95% CI 1.43-2.13) versus 4.18 days (95% CI 3.59-4.78); p<0.001]. Likewise, the mean time from onset of symptoms until PCR results were available was 3.46 days (95% CI 3-3.92) for H1N1 patients and 6.7 days (95% CI 5.85-7.54) for ILI patients (p<0.001). No significant difference could be observed in either number of patients who needed ICU admission (8% H1N1 influenza versus 5% ILI) nor in the mean age of patients who needed intensified care (44.4 years versus 43.8 years). Rapid influenza antigen tests (BinaxNow, Inverness Medical, Maine, U.S.) turned out to be unreliable because of their low sensitivity. In 89.3% of tests in H1N1 influenza patients, a false negative result was observed. H1N1 influenza patients were more likely to present with fever (92.2% versus 73.9%; p<0.001), cough (72.7% versus 51.5%; p<0.001), rhinitis (23% versus 14.3%; p=0.012), fatigue (59.1% versus 22.5%; p<0.001) and headache (31.6% versus 23.1%; p=0.033) and had a significant higher initial heart rate (107.3 bpm versus 98.2 bpm; p=0.008). However H1N1 influenza patients presented less often with abdominal pain (5.7% versus 10.7%; p=0.048). Furthermore H1N1 influenza patients had significantly fewer underlying co-morbidities (coronary heart disease 4.3% versus 10.2%, p=0.015; cardiac insufficiency 2.9% versus 8.8%, p=0.007; arterial hypertension 12% versus 23.5%, p<0.001; liver disease 2.9% versus 12.7%, p<0.001; chronic renal failure 4.8% versus 12.4%; p=0.003). 1.9% of H1N1 influenza and 3.2% of ILI patients died (p=0,424). Conclusion: Our data has shown that H1N1 influenza patients presented 1.78 days after onset of symptoms, and PCR results needed 1.68 days on average until they were available, after first clinical presentation. Furthermore it was found that the rapid influenza antigen tests were unreliable. In our study, cough, rhinitis, fatigue and fever turned out to be significant clinical predictors for H1N1 influenza. A lack of fever may be used as exclusion criteria for H1N1 influenza. Presented data may help to develop a clinical score for early treatment decisions inH1N1 influenza.