Anna M. Bramley

Hospitalized Patients with 2009 H1N1 Influenza in the United States, April–June 2009

BACKGROUND During the spring of 2009, a pandemic influenza A (H1N1) virus emerged and spread globally. We describe the clinical characteristics of patients who were hospitalized with 2009 H1N1 influenza in the United States from April 2009 to mid-June 2009. METHODS Using medical charts, we collected data on 272 patients who were hospitalized for at least 24 hours for influenza-like illness and who tested positive for the 2009 H1N1 virus with the use of a real-time reverse-transcriptase-polymerase-chain-reaction assay. RESULTS Of the 272 patients we studied, 25% were admitted to an intensive care unit and 7% died. Forty-five percent of the patients were children under the age of 18 years, and 5% were 65 years of age or older. Seventy-three percent of the patients had at least one underlying medical condition; these conditions included asthma; diabetes; heart, lung, and neurologic diseases; and pregnancy. Of the 249 patients who underwent chest radiography on admission, 100 (40%) had findings consistent with pneumonia. Of the 268 patients for whom data were available regarding the use of antiviral drugs, such therapy was initiated in 200 patients (75%) at a median of 3 days after the onset of illness. Data suggest that the use of antiviral drugs was beneficial in hospitalized patients, especially when such therapy was initiated early. CONCLUSIONS During the evaluation period, 2009 H1N1 influenza caused severe illness requiring hospitalization, including pneumonia and death. Nearly three quarters of the patients had one or more underlying medical conditions. Few severe illnesses were reported among persons 65 years of age or older. Patients seemed to benefit from antiviral therapy.

Community-Acquired Pneumonia Requiring Hospitalization among U.S. Adults

BACKGROUND Community-acquired pneumonia is a leading infectious cause of hospitalization and death among U.S. adults. Incidence estimates of pneumonia confirmed radiographically and with the use of current laboratory diagnostic tests are needed. METHODS We conducted active population-based surveillance for community-acquired pneumonia requiring hospitalization among adults 18 years of age or older in five hospitals in Chicago and Nashville. Patients with recent hospitalization or severe immunosuppression were excluded. Blood, urine, and respiratory specimens were systematically collected for culture, serologic testing, antigen detection, and molecular diagnostic testing. Study radiologists independently reviewed chest radiographs. We calculated population-based incidence rates of community-acquired pneumonia requiring hospitalization according to age and pathogen. RESULTS From January 2010 through June 2012, we enrolled 2488 of 3634 eligible adults (68%). Among 2320 adults with radiographic evidence of pneumonia (93%), the median age of the patients was 57 years (interquartile range, 46 to 71); 498 patients (21%) required intensive care, and 52 (2%) died. Among 2259 patients who had radiographic evidence of pneumonia and specimens available for both bacterial and viral testing, a pathogen was detected in 853 (38%): one or more viruses in 530 (23%), bacteria in 247 (11%), bacterial and viral pathogens in 59 (3%), and a fungal or mycobacterial pathogen in 17 (1%). The most common pathogens were human rhinovirus (in 9% of patients), influenza virus (in 6%), and Streptococcus pneumoniae (in 5%). The annual incidence of pneumonia was 24.8 cases (95% confidence interval, 23.5 to 26.1) per 10,000 adults, with the highest rates among adults 65 to 79 years of age (63.0 cases per 10,000 adults) and those 80 years of age or older (164.3 cases per 10,000 adults). For each pathogen, the incidence increased with age. CONCLUSIONS The incidence of community-acquired pneumonia requiring hospitalization was highest among the oldest adults. Despite current diagnostic tests, no pathogen was detected in the majority of patients. Respiratory viruses were detected more frequently than bacteria. (Funded by the Influenza Division of the National Center for Immunizations and Respiratory Diseases.).

Morbid Obesity as a Risk Factor for Hospitalization and Death Due to 2009 Pandemic Influenza A(H1N1) Disease

Background Severe illness due to 2009 pandemic A(H1N1) infection has been reported among persons who are obese or morbidly obese. We assessed whether obesity is a risk factor for hospitalization and death due to 2009 pandemic influenza A(H1N1), independent of chronic medical conditions considered by the Advisory Committee on Immunization Practices (ACIP) to increase the risk of influenza-related complications. Methodology/Principal Findings We used a case-cohort design to compare cases of hospitalizations and deaths from 2009 pandemic A(H1N1) influenza occurring between April–July, 2009, with a cohort of the U.S. population estimated from the 2003–2006 National Health and Nutrition Examination Survey (NHANES); pregnant women and children <2 years old were excluded. For hospitalizations, we defined categories of relative weight by body mass index (BMI, kg/m2); for deaths, obesity or morbid obesity was recorded on medical charts, and death certificates. Odds ratio (OR) of being in each BMI category was determined; normal weight was the reference category. Overall, 361 hospitalizations and 233 deaths included information to determine BMI category and presence of ACIP-recognized medical conditions. Among ≥20 year olds, hospitalization was associated with being morbidly obese (BMI≥40) for individuals with ACIP-recognized chronic conditions (OR = 4.9, 95% CI 2.4–9.9) and without ACIP-recognized chronic conditions (OR = 4.7, 95%CI 1.3–17.2). Among 2–19 year olds, hospitalization was associated with being underweight (BMI≤5th percentile) among those with (OR = 12.5, 95%CI 3.4–45.5) and without (OR = 5.5, 95%CI 1.3–22.5) ACIP-recognized chronic conditions. Death was not associated with BMI category among individuals 2–19 years old. Among individuals aged ≥20 years without ACIP-recognized chronic medical conditions death was associated with obesity (OR = 3.1, 95%CI: 1.5–6.6) and morbid obesity (OR = 7.6, 95%CI 2.1–27.9). Conclusions/Significance Our findings support observations that morbid obesity may be associated with hospitalization and possibly death due to 2009 pandemic H1N1 infection. These complications could be prevented by early antiviral therapy and vaccination.

Burden of seasonal influenza hospitalization in children, United States, 2003 to 2008.

OBJECTIVES To estimate the rates of hospitalization with seasonal influenza in children aged <18 years from a large, diverse surveillance area during 2003 to 2008. STUDY DESIGN Through the Emerging Infections Program Network, population-based surveillance for laboratory-confirmed influenza was conducted in 10 states, including 5.3 million children. Hospitalized children were identified retrospectively; clinicians made influenza testing decisions. Data collected from the hospital record included demographics, medical history, and clinical course. Incidence rates were calculated with census data. RESULTS The highest hospitalization rates occurred in children aged <6 months (seasonal range, 9-30/10 000 children), and the lowest rates occurred in children aged 5 to 17 years (0.3-0.8/10 000). Overall, 4015 children were hospitalized, 58% of whom were identified with rapid diagnostic tests alone. Forty percent of the children who were hospitalized had underlying medical conditions; asthma (18%), prematurity (15% of children aged <2 years), and developmental delay (7%) were the most common. Severe outcomes included intensive care unit admission (12%), respiratory failure (5%), bacterial coinfection (2%), and death (0.5%). CONCLUSIONS Influenza-associated hospitalization rates varied by season and age and likely underestimate true rates because many hospitalized children are not tested for influenza. The proportion of children with severe outcomes was substantial across seasons. Quantifying incidence of influenza hospitalization and severe outcomes is critical to defining disease burden.

Respiratory Viral Detection in Children and Adults: Comparing Asymptomatic Controls and Patients With Community-Acquired Pneumonia

Abstract Background. The clinical significance of viruses detected in patients with community-acquired pneumonia (CAP) is often unclear. Methods. We conducted a prospective study to identify the prevalence of 13 viruses in the upper respiratory tract of patients with CAP and concurrently enrolled asymptomatic controls with real-time reverse-transcriptase polymerase chain reaction. We compared age-stratified prevalence of each virus between patients with CAP and controls and used multivariable logistic regression to calculate attributable fractions (AFs). Results. We enrolled 1024 patients with CAP and 759 controls. Detections of influenza, respiratory syncytial virus, and human metapneumovirus were substantially more common in patients with CAP of all ages than in controls (AFs near 1.0). Parainfluenza and coronaviruses were also more common among patients with CAP (AF, 0.5–0.75). Rhinovirus was associated with CAP among adults (AF, 0.93) but not children (AF, 0.02). Adenovirus was associated with CAP only among children <2 years old (AF, 0.77). Conclusions. The probability that a virus detected with real-time reverse-transcriptase polymerase chain reaction in patients with CAP contributed to symptomatic disease varied by age group and specific virus. Detections of influenza, respiratory syncytial virus, and human metapneumovirus among patients with CAP of all ages probably indicate an etiologic role, whereas detections of parainfluenza, coronaviruses, rhinovirus, and adenovirus, especially in children, require further scrutiny.

Association Between Hospitalization With Community-Acquired Laboratory-Confirmed Influenza Pneumonia and Prior Receipt of Influenza Vaccination

IMPORTANCE Few studies have evaluated the relationship between influenza vaccination and pneumonia, a serious complication of influenza infection. OBJECTIVE To assess the association between influenza vaccination status and hospitalization for community-acquired laboratory-confirmed influenza pneumonia. DESIGN, SETTING, AND PARTICIPANTS The Etiology of Pneumonia in the Community (EPIC) study was a prospective observational multicenter study of hospitalizations for community-acquired pneumonia conducted from January 2010 through June 2012 at 4 US sites. In this case-control study, we used EPIC data from patients 6 months or older with laboratory-confirmed influenza infection and verified vaccination status during the influenza seasons and excluded patients with recent hospitalization, from chronic care residential facilities, and with severe immunosuppression. Logistic regression was used to calculate odds ratios, comparing the odds of vaccination between influenza-positive (case) and influenza-negative (control) patients with pneumonia, controlling for demographics, comorbidities, season, study site, and timing of disease onset. Vaccine effectiveness was estimated as (1 - adjusted odds ratio) × 100%. EXPOSURE Influenza vaccination, verified through record review. MAIN OUTCOMES AND MEASURES Influenza pneumonia, confirmed by real-time reverse-transcription polymerase chain reaction performed on nasal/oropharyngeal swabs. RESULTS Overall, 2767 patients hospitalized for pneumonia were eligible for the study; 162 (5.9%) had laboratory-confirmed influenza. Twenty-eight of 162 cases (17%) with influenza-associated pneumonia and 766 of 2605 controls (29%) with influenza-negative pneumonia had been vaccinated. The adjusted odds ratio of prior influenza vaccination between cases and controls was 0.43 (95% CI, 0.28-0.68; estimated vaccine effectiveness, 56.7%; 95% CI, 31.9%-72.5%). CONCLUSIONS AND RELEVANCE Among children and adults hospitalized with community-acquired pneumonia, those with laboratory-confirmed influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received influenza vaccination.

Influenza-Associated Pneumonia Among Hospitalized Patients With 2009 Pandemic Influenza A (H1N1) Virus—United States, 2009

BACKGROUND Pneumonia was a common complication among hospitalized patients with 2009 pandemic influenza A H1N1 [pH1N1] in the United States in 2009. METHODS Through 2 national case series conducted during spring and fall of 2009, medical records were reviewed. A pneumonia case was defined as a hospitalized person with laboratory-confirmed pH1N1 virus and a chest radiographic report consistent with pneumonia based on agreement among 3 physicians. RESULTS Of 451 patients with chest radiographs performed, 195 (43%) had pneumonia (spring, 106 of 237 [45%]; fall, 89 of 214 [42%]). Compared with 256 patients without pneumonia, these 195 patients with pneumonia were more likely to be admitted to the intensive care unit (52% vs 16%), have acute respiratory distress syndrome (ARDS; 26% vs 2%), have sepsis (18% vs 3%), and die (17% vs 2%; P < .0001). One hundred eighteen (61%) of the patients with pneumonia had ≥1 underlying condition. Bacterial infections were reported in 13 patients with pneumonia and 2 patients without pneumonia. Patients with pneumonia, when compared with patients without pneumonia, were equally likely to receive influenza antiviral agents (78% vs 79%) but less likely to receive antiviral agents within ≤2 days of illness onset (28% vs 50%; P < .0001). CONCLUSIONS Hospitalized patients with pH1N1 and pneumonia were at risk for severe outcomes including ARDS, sepsis, and death; antiviral treatment was often delayed. In the absence of accurate pneumonia diagnostics, patients hospitalized with suspected influenza and lung infiltrates on chest radiography should receive early and aggressive treatment with antibiotics and influenza antiviral agents.

Staphylococcus aureus Community-acquired Pneumonia: Prevalence, Clinical Characteristics, and Outcomes

Despite low prevalence of methicillin-resistant Staphylococcus aureus (MRSA; 0.7%), nearly one-third of adults hospitalized with community-acquired pneumonia (CAP) received anti-MRSA antibiotics. Characteristics of MRSA and pneumococcal CAP overlapped substantially, highlighting the challenge of accurately targeting anti-MRSA antibiotics using clinical criteria.

Intensive care unit patients with 2009 pandemic influenza A (H1N1pdm09) virus infection - United States, 2009.

Please cite this paper as: Bramley et al. Intensive care unit patients with 2009 pandemic influenza A (H1N1pdm09) virus infection – United States, 2009. Influenza and Other Respiratory Viruses 6(601), e134–e142.

Asthma in patients hospitalized with pandemic influenza A(H1N1)pdm09 virus infection-United States, 2009

BackgroundAsthma was the most common co-morbidity among patients hospitalized with pandemic influenza A(H1N1)pdm09 [pH1N1] infection. The objective was to compare characteristics of hospitalized pH1N1 patients with and without asthma and assess factors associated with severity among asthma patients.MethodsPatient data were derived from two 2009 pandemic case-series of U.S. pH1N1 hospitalizations. A case was defined as a person ≥ 2 years old hospitalized with laboratory-confirmed pH1N1. Asthma status was determined through chart review.ResultsAmong 473 cases, 29% had asthma. Persons with asthma were more likely to be 2–17 years old (39% vs. 30%, p = 0.04) and black (29% vs. 18%, p < 0.01), and have chronic obstructive pulmonary disease (13% vs. 9%, p = 0.04) but less likely to have pneumonia (37% vs. 47%, p = 0.05), need mechanical ventilation (13% vs. 23%, p = 0.02), and die (4% vs. 10%, p = 0.04) than those without asthma. Among patients with asthma, those admitted to an intensive care unit (ICU) or who died (n = 38) compared with survivors not admitted to an ICU (n = 99) were more likely to have pneumonia on admission (60% vs. 27%, p < 0.01) or acute respiratory distress syndrome (24% vs. 0%, p < 0.01) and less likely to receive influenza antiviral agents ≤ 2 days of admission (73% vs. 92%, p = 0.02).ConclusionsThe majority of persons with asthma had an uncomplicated course; however, severe disease, including ICU admission and death, occurred in asthma patients who presented with pneumonia. Influenza antiviral agents should be started early in hospitalized patients with suspected influenza, including those with asthma.