Differences in clinical outcomes after 2009 influenza A/H1N1 and seasonal influenza among hematopoietic cell transplant recipients

Abstract

It is not known whether pandemic 2009 influenza A/H1N1 (2009 H1N1) leads to more serious disease than seasonal influenza in hematopoietic cell transplant (HCT) recipients. In a retrospective study in HCT recipients with virologically proven influenza virus infection, a total of 161 HCT recipients (18 2009 H1N1, 103 seasonal influenza A, and 40 seasonal influenza B) were analyzed. In multivariable analyses, more patients with 2009 H1N1 had lower respiratory tract disease (LRD), hypoxemia, and prolonged viral shedding compared with seasonal influenza A. Seasonal influenza A and B outcomes were similar. There was no difference in overall and influenza-associated mortality among influenza virus types. Both early and delayed administration of antiviral therapy was shown to be beneficial in terms of decreased rates of development of LRD, although earlier intervention appeared to be more effective. Profound lymphopenia and lack of early antiviral therapy were associated significantly with LRD, hypoxemia, and death. High-dose corticosteroid treatment (≥ 1 mg/kg) given at the time of influenza diagnosis was associated with a reduced risk for mechanical ventilation. Thus, our data suggest that infection with 2009 influenza A/H1N1 resulted in more severe respiratory disease in HCT recipients compared with seasonal influenza.

Pandemic 2009 Influenza A (H1N1) virus infection in cancer and hematopoietic stem cell transplant recipients; a multicenter observational study.

“…These data explain our high mortality rate observed among the 17 patients who were admitted to ICU (11/17; 65%) or among the 12 patients who developed respiratory failure (11/12; 92%). These values are comparable to those reported in the same type of population 1, 8, 12, 22 , but are higher than those reported in other populations, which ranged from 0–24% 21, 26– 29 . Indeed, the overall mortality rate observed among Argentinean patients admitted to ICU and requiring mechanical ventilation was 46% 25 .…”

“…The incidence of pneumonia we found is higher than the one reported with seasonal influenza in cancer patients (5–44%) 3, 18– 20 and it is also higher than the incidence of lower respiratory tract infections (LRTI) caused by the 2009 pandemic Influenza A H1N1 in the hospitalized general population (40–44%) 21 , in solid organ transplant recipients (23%) 16 , in HCT recipients (21–56%) 1, 6, 8, 12– 14, 22 and in patients with hematological malignancies (48%) 23 . Only one small study that includes 15 confirmed cases of 2009 pandemic Influenza A H1N1 infection in onco-hematological patients reports a higher incidence of pneumonia (87%) 15 .…”

“…The pandemic Influenza A H1N1 virus is an independent risk factor for progression to LRTI (OR 5.64; 95% CI 1.3-25) and hypoxemia (OR 5.91; 95% 1.4–24) compared with seasonal influenza virus in HCT recipients 1 . In addition, immunosuppression was a main risk factor for early mortality among 337 Argentinean patients admitted to ICU with influenza like illness and respiratory failure that required mechanical ventilation.…”

“…During influenza season, 20 to 30% of stem cell transplant SCT recipients with respiratory symptoms can test positive for Influenza with a mortality rate of up to 28% 1 . Non-transplant cancer patients can also have a high mortality rate of up to 38% 2 , being higher in patients with lung, hematological and colorectal cancer, in patients that develop lower respiratory tract infections, and in patients with other co-morbid conditions.…”

“…Many studies from different countries were reported 1, 6– 16 . In these studies, the incidence of pneumonia ranges from 20 11 to 52% 8 , while the reported mortality rate ranges from 0–10% 6, 11, 12, 14, 16 to as high as 21–31% 7– 10, 15 .…”