May 9, 2013

Thrombocytopenia as a mortality risk factor in acute respiratory failure in H1N1 influenza


Original article | Published 18 April 2013, doi:10.4414/smw.2013.13788
Cite this as: Swiss Med Wkly. 2013;143:w13788

Thrombocytopenia as a mortality risk factor in acute respiratory failure in H1N1 influenza

Juan Carlos Lopez-Delgadoa, Assumpta Rovirab, Francisco Estevea, Nicolás Ricob, Rafael Mañez Mendiluce, Josep Ballús Nogueraa, Julián Berradeb
Hospital Universitari de Bellvitge, Intensive Care Department, IDIBELL (Institut d’Investigació Biomèdica Bellvitge; Biomedical Investigation Institute of Bellvitge), L’Hospitalet de Llobregat, Barcelona, Spain
b Hospital General de L’Hospitalet, Intensive Care Department, CSI (Consorci Sanitari Integral), L’Hospitalet de Llobregat, Barcelona, Spain

Summary

BACKGROUND: A small proportion of patients with influenza H1N1 rapidly develop acute respiratory failure and are a problem for intensive care units (ICUs). Although certain clinical risk factors have been identified, few measurable biochemical/haematological markers able to predict poor outcome have been reported. The aims of the present report are to show which variables on and during admission are associated with increased in-hospital mortality in patients admitted to the ICU with acute respiratory failure due to H1N1 influenza.
METHODS: A prospective observational study at two ICUs was carried out between August 2009 and March 2011. The study period covered two waves of pandemic influenza A H1N1 in Spain. Clinical and laboratory data on and during ICU admission were recorded for the purpose of analysis.
RESULTS: Sixty patients with acute respiratory failure due to H1N1 influenza were admitted during the period described above; 63.3% (n = 38) were male and the mean age was 49.2 ± 14 years. Regarding comorbidities, 46.7% (n = 28) were smokers, 38% (n = 23) had hypertension, 30% (n = 18) had a body mass index (BMI) >30 kg/m2, 30% (n = 18) had chronic obstructive pulmonary disease and 26% (n = 16) had cardiac insufficiency; 16.6% (n = 10) had bacterial co-infection, 70% (n = 42) required invasive mechanical ventilation and 48.3% (n = 29) non-invasive mechanical ventilation. Mortality was 20% (n = 12). Comparing survivors with non-survivors, univariate analysis revealed significant differences in BMI, creatinine, haemoglobin, platelets, arterial pH, pCO2, and the rate of bacterial co-infection. In the multivariate analysis, only the presence of lower platelet count was statistically significant (214 ± 101 vs 113 ± 82 ×109/L; = 0.009). Patients with thrombocytopenia showed a lower in-hospital survival rate (55%vs92.5%; Log Rank = 0.008).
CONCLUSIONS: Thrombocytopenia could be valuable marker of in-hospital mortality in patients with respiratory failure due to H1N1 influenza in the ICU scenario.
Key words: thrombocytopenia; influenza H1N1; acute respiratory failure; Intensive Care Units; in-hospital mortality; risk factors

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