Background: Respiratory syncytial virus (RSV) is becoming increasingly recognized as a serious threat to vulnerable population subgroups. The Epidemiology, Burden, and Cost (EBC) of RSV Infection Study is a retrospective cohort study of adults hospitalized for acute respiratory infection (ARI) designed to estimate the population burden of RSV especially for specific groups such as the elderly, pregnant women and solid organ transplant patients. This paper describes the design and statistical analysis plan for the study. Methods: The study population will consist of residents of Allegheny County, Pennsylvania ≥18 years of age who were hospitalized in Pennsylvania during the period September 1, 2015 to August 31, 2018. Several data sources will be used including U.S. Census, Pennsylvania Health Care Cost Containment Council (PHC4), and the electronic medical record for the health system to which the hospitals belong. The algorithm involves: 1) ARI-associated hospitalizations in PHC4 data; 2) adjustment for ARI hospitalizations among county residents but admitted to hospitals outside the county, and 3) RSV detections from respiratory viral panels (RVPs). Key sensitivity analyses will adjust for undertesting for viruses in the fall and spring quarters. The results will be population-based estimates, stratified by age and risk groups. Conclusion: Adjusting hospitalization data using a multiplier method is a relatively simple means to estimate the impact of RSV in a given area. This algorithm can be applied to other health systems and localities to estimate burden of RSV in adults, as well as burden of other respiratory pathogens.

Background: Acute respiratory infections (ARIs) result in millions of illnesses and hundreds of thousands of hospitalizations annually in the US. The responsible viruses include influenza, parainfluenza, human metapneumovirus, coronaviruses, respiratory syncytial virus (RSV), and human rhinoviruses. This study estimated the population-based hospitalization burden of 18 respiratory viruses (RV) over 4 years, from 7/1/2015 to 6/30/2019 among adults ≥18 years of age for Allegheny County (Pittsburgh), Pennsylvania. Methods: We used population-based statewide hospital discharge data, health system electronic medical record (EMR) data for RV tests, census data, and a published method to calculate burden. Results: Among 26,211 eligible RV tests, 67.6% were negative for any virus. The viruses detected were rhinovirus/enterovirus (2,552; 30.1%), influenza A (2,299; 27.1%), RSV (1,082; 12.7%), human metapneumovirus (832; 9.8%), parainfluenza (601; 7.1%), influenza B (565; 6.7%), non-SARS-CoV-2 coronavirus (420; 4.9% 1.5 years of data available), and adenovirus (136; 1.6%). Most tests were among female (58%) and white (71%) patients with 60% of patients ≥65 years, 24% 50-64 years and 16% 18-49 years. The annual burden, ranged from 137-174/100,000 population for rhinovirus/enterovirus; 99-182/100,000 for influenza A; 56-81/100,000 for RSV. Among adults <65 years, rhinovirus/enterovirus hospitalization burden was higher than influenza A; whereas the reverse was true for adults ≥65 years. RV hospitalization burden increased with increasing age. Conclusions: These virus-specific ARI population-based hospital burden estimates showed significant non-influenza burden. These estimates can serve as the basis for several areas of research that are essential for setting funding priorities and guiding public health policy.