Characteristics and outcome of critically ill patients with 2009 H1N1 influenza infection in Syria

Abstract

Objectives:To describe the epidemiologic characteristics, clinical features, and outcome of severe cases of 2009 H1N1 influenza A infections who were admitted to the intensive care units (ICUs) in Damascus, Syria.Materials and Methods:Retrospectively, we collected clinical data on all patients who were admitted to the ICU with confirmed or suspected diagnosis of severe 2009 H1N1 influenza A with respiratory failure at 4 major tertiary care hospitals in Damascus, Syria. Acute Physiology and Chronic Health Evaluation (APACHE) II system was used to assess the severity of illness within the first 24 h after admission. The outcome was overall hospital mortality.Results:Eighty patients were admitted to the ICU with severe 2009 H1N1 infection. The mean age was 40.7 years; 69.8% of patients had ≥1 of the risk factors: asthmatics 20%, obesity 23.8%, and pregnancy 5%; and 72.5% had acute lung injury or adult respiratory distress syndrome, 12.5% had viral pneumonia, 42.5% had secondary bacterial pneumonia, and 15% had exacerbation of airflow disease. Mechanical ventilation was required in 73.7% of cases. The mean hospital length of stay was 11.7 days (median 8 days, range 0–77 days, IQR: 5–14 days). The overall mortality rate was 51% for a mean APACHE II score of 15.2 with a predicted mortality of 21% (standardized mortality ratio of 2.4, 95% confidence interval: 1.7–3.2, P value < 0.001).Conclusion:Critically ill patients with severe 2009 H1N1 infection in this limited resource country had a much higher mortality rate than the predicted APACHE II mortality rate or when compared with the reported mortality rates for severe cases in other countries during 2009 H1N1 pandemic.

Global Burden of Influenza as a Cause of Cardiopulmonary Morbidity and Mortality

“…As suggested by the data in Syria and India, despite markedly lower SOFA and APACHE II scores in resource-limited countries, there is higher mortality in these settings (Table 3) (42, 67). Further, mortality rates from ICUs in upper-middle income countries, including Mexico and Tunisia, suggest that resource-availability is linked to outcomes in severe disease there as well.…”

“…Further, mortality rates from ICUs in upper-middle income countries, including Mexico and Tunisia, suggest that resource-availability is linked to outcomes in severe disease there as well. Mortality rates in both countries were in-between those from lower- and higher- income countries (Table 3) (11, 42, 57, 58, 67–72). Disparities in access to critical care resources may partly explain some of the pandemic influenza mortality differences reported among high and low-income countries.…”

“…Autopsy reports suggest that close to 95% of severe illness and death were associated with bacterial co-infection (73). Infection with the 2009 H1N1 pandemic strain was also associated with secondary bacterial infection in approximately 20–40% of ICU patients in most studies (Table 3) (57, 58, 67). The pathogenesis underlying influenza-bacterial co-infection is likely multifactorial and involves changes to both the airway defense including decreased mechanical clearance of invading bacteria through deficient ciliary movement and breakdown of the airway epithelium.…”

“…The pathogenesis of influenza-induced ARDS has been reviewed previously (66). The 2009 pandemic H1N1 virus led to ARDS in 30–80% of patients admitted to an intensive care unit with increased percentages associated with lower-income countries (Table 3) (11, 42, 57, 58, 67–72). …”

“…In a retrospective review of 80 patients admitted to four ICUs in Damascus, Syria, 58 (72.5%) had acute lung injury or ARDS and 59 (73.7%) were mechanically ventilated (67). APACHE II and SOFA scores reported in Syria were similar to those in South India (15.2 and 5 respectively) and ICU mortality was similarly elevated at 51% (42).…”