At-Risk Populations

^*An observational, retrospective, cohort study conducted at an integrated healthcare system evaluated adults aged ≥60 years hospitalized with RSV infection (N=645) or influenza A/B infection (N=1,878) over 5 consecutive seasons between January 2011 and June 2015 to compare demographics, prehospitalization characteristics, hospital utilization, and clinical outcomes.³

^†The objective of the study was to evaluate patterns of hospital readmissions for adults with pneumonia within 30 days after discharge, stratified by age (18 to 44, 45 to 64, and ≥65 years; mean=69 years, distributed roughly equally by gender). Data came from the Nationwide Readmissions Database of the Agency of Healthcare Research and Quality, a nationally representative, all-payer database captured from 12 geographically dispersed states. Adults aged ≥18 years with a diagnosis of pneumonia, hospitalized and discharged between 2013 and 2014, were followed for readmission for pneumonia within 30 days after discharge. Pneumonia discharges were identified in nearly 630,000 patients from a weighted estimate of nearly 1.5 million discharges nationally. All demographic characteristics and comorbidities were assessed for all patients as possible predictors of readmission. Cardiovascular comorbidities, including coronary artery disease, history of CABG, arrhythmia, valvular heart disease, acute myocardial infarction (AMI), COPD, tobacco smoking, malignancy, malnutrition, and anemia were significantly more frequent in older adults (≥65 years) entering the study. The unadjusted all-cause readmission rate was highest in adults aged ≥65 years (16.7%; P<0.001). When risk-adjusted for comorbidities, end stage renal disease or dialysis were associated with the highest odds of readmission for pneumonia at 30 days (OR 1.88; 95% CI, 1.79, 1.96). Other significant comorbidities predictive of readmission for pneumonia included metastatic malignancy or leukemia, chronic skin ulcer, congestive heart failure, and anemia. Among comorbidities not included in the CMS comorbidity model but contained in another comorbidity model (Elixhauser et al), collagen vascular diseases, hepatic and pulmonary circulatory diseases, obesity, and weight loss were significant predictors of readmission. Males in both the CMS and Elixhauser models, aged ≥45 years and ≥65 years, respectively, had higher odds ratios compared to females for readmission. Comparing the 45 to 64 and the ≥65 year age groups, the odds of readmission were higher in the younger group with respect to those with various solid and liquid tumors and renal failure. Hypertension was independently associated with significantly higher odds of readmission in the younger age group compared with the older group (P<0.001).⁴

^‡The design of the study was a cross-sectional analysis of RSV Hospitalization Surveillance Network (RSV-NET) data and used detailed medical record abstraction of 6,248 hospitalized patients with RSV. Data was from a random sample of patients aged 50 years and older from 12 different US states over 5 RSV seasons from 2014 to 2015 through 2017 to 2018, in addition to 2022 to 2023. The prevalence of one or more discharge-coded acute cardiac events was reported as acute heart failure, acute ischemic heart disease, hypertensive crisis, ventricular tachycardia, cardiogenic shock, or other acute cardiac event (cardiomyopathy, viral cardiomyopathy, myocarditis, pericarditis, and endocarditis). The reference group was patients who experienced no acute cardiac event.⁶

^§Based on a 2018 summary of the current medical literature for new/worsening heart failure, new/worsening arrhythmias, myocardial infarctions, and/or strokes in adult patients hospitalized with CAP.⁷

^¶Self-controlled case series analysis using Canadian insurance claims data, which evaluated the association between laboratory-confirmed influenza or other respiratory pathogens, and AMI. A "risk interval" for the association between laboratory-confirmed influenza and hospitalization for AMI was defined as 7 days after respiratory specimen collection and the "control interval" defined as 1 year before and 1 year after the positive influenza test. Patients (median age: 77 years [IQR: 65-86]) underwent testing for one or more respiratory viruses between 2009 and 2014, including 148,307 influenza testing episodes with all respiratory pathogens tested the same day per patient. Patients were positive for influenza in 19,729 tests. The primary analysis consisted of 364 patients hospitalized for AMI among 332 patients with laboratory-confirmed influenza. The rate for previous hospitalizations for AMI was 24%. Diabetes was an established risk factor in 49% of patients. Thirty-eight percent of patients had dyslipidemia, and 85% had hypertension. Among flu infections, influenza type A viruses were the predominant type. Only 31% of patients had been vaccinated against influenza. The incidence ratio of an admission for AMI after laboratory-confirmed influenza during the 7-day risk interval (20 admissions per week) compared with the control interval (344 admissions [3.3 admissions per week]) was 6.05 (95% CI, 3.86, 9.50).⁸

^#The composite vaccination measure includes vaccines that are routinely recommended for all adults (influenza and tetanus toxoid-containing vaccines) or indicated based on age (pneumococcal and herpes zoster). Adults who received all age-appropriate vaccines were included in the measure. Question asked of respondents for: influenza vaccination, if they had received an influenza shot or nasal spray during the preceding 12 months and, if so, in which month and year; pneumococcal vaccination, if they had ever had a pneumonia shot; herpes zoster vaccination, if they had ever received a shingles vaccine and, if yes, if they ever had RZV, number of vaccine doses received, and timing of vaccine receipt; tetanus-containing vaccine, if they had received a tetanus shot in the past 10 years, and, if yes, if their most recent shot included Tdap.⁹

^||Data collected from 2009 to 2010 through 2013 to 2014 seasons in FluSurv-NET. Data presented represents adjusted odds ratios based on 33,515 laboratory-confirmed influenza-associated hospitalizations using a population-based surveillance system at 14 sites across the US.¹⁰

AMI=acute myocardial infarction; CABG=coronary artery bypass grafting; CAP=community-acquired pneumonia; CI=confidence interval; CMS=Centers for Medicare and Medicaid Services; COPD=chronic obstructive pulmonary disease; IQR=interquartile range; OR=odds ratio; RSV=respiratory syncytial virus.