Severe pandemic H1N1 and seasonal influenza in children and young adults with sickle cell disease

Abstract

Influenza causes excess morbidity in sickle cell disease (SCD). H1N1 pandemic influenza has been severe in children. To compare H1N1 with seasonal influenza in SCD (patients younger than 22), we reviewed medical records (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)). We identified 123 cases of laboratory-confirmed influenza (94 seasonal, 29 H1N1). Those with seasonal influenza were younger (median 4.4 vs 8.7 years old, P ‫؍‬ .006) and had less asthma (24% vs 56%, P ‫؍‬ .002). Those with H1N1 influenza more often had acute chest syndrome (ACS; 34% vs 13%, P ‫؍‬ .01) and required intensive care (17% vs 3%, P ‫؍‬ .02), including mechanical ventilation (10% vs 0%, P ‫؍‬ .02). In multivariate analysis, older age (odds ratio [OR] 1.1 per year, P ‫؍‬ .04) and H1N1 influenza (OR 3.0, P ‫؍‬ .04) were associated with ACS, and older age (OR 1.1 per year, P ‫؍‬ .02) and prior ACS (OR 3.3 per episode in last year, P < .006) with intensive care. Influenza, especially H1N1, causes critical illness in SCD and should be prevented. IntroductionInfluenza causes disproportionate morbidity in sickle cell disease (SCD), an inherited hemoglobinopathy affecting 1 in 2500 children in the United States. 1 In one study, SCD was associated with a 56-fold increased risk of influenza-related hospitalization. 2 Yet, despite its effectiveness, 3,4 most children with SCD do not receive the influenza vaccine yearly. 5 Recognition of the influenza A virus of swine origin (H1N1) in March 2009 6 caused heightened concern. Case series of H1N1 influenza in SCD have reported severe illness, with 10 in 21 children and 2 in 2 adults developing acute chest syndrome (ACS). 7,8 To assess the relative severity of pandemic H1N1 versus seasonal influenza in SCD, we performed a comprehensive analysis at our institution. Methods Study populationWe identified patients aged Ͻ 22 years with SCD and influenza by searching for SCD and respiratory virus testing from September 1, 1993, to April 30, 2007, in the discharge and billing databases of Johns Hopkins Hospital (JHH). From May 1, 2007, to December 10, 2009, we also prospectively identified patients with SCD and influenza admitted to the pediatric hematology service or seen in the pediatric emergency department at JHH. We reviewed clinical records to identify influenza vaccination and administrative records to estimate the number of patients aged Ͻ 22 years with SCD seen at JHH. Additional information appears in supplemental data (available on the Blood Web site; see the Supplemental Materials link at the top of the online article). DefinitionsWe defined influenza as laboratory-confirmed influenza A or B and ACS as a new pulmonary infiltrate involving Ն 1 complete lung segment with fever (Ͼ 38.5°C), tachypnea, cough, wheezing, or chest pain. 9 We defined severe pain as pain requiring Ͼ 2 doses of opiates and asthma exacerbation as bronchodilator-treated wheezing. Diagnosis of influenzaInfluenza was detected by rapid antigen-based test (immunochromatograp...

Lung vaso-occlusion in sickle cell disease mediated by arteriolar neutrophil-platelet microemboli

“…This observation is consistent with the clinical presentation in SCD patients. While SCD patients as well as normal healthy humans can develop acute lung injury and pneumonia with severe injury or infection with highly pathogenic bacteria, SCD patients are exquisitely susceptible to acute lung injury when exposed to less severe triggers (5,18,22,36).…”

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

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Wheezing in children with sickle cell disease

“…Retrospective cohorts typically report lower rates of wheezing 4–9 with estimates ranging from 3.6% to 18.7%. Many of the retrospective estimates were based on specialty practices that do not reflect the full spectrum of either asthma or sickle cell disease.…”