Low Levels of RSV Testing Among Adults Hospitalized for Lower Respiratory Tract Infection in the United States

Introduction Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection (LRTI)-related hospitalizations in older adults. Without RSV-specific treatment for adults, testing is uncommon, leading to potential underestimation of RSV incidence in real-world data studies. This study aimed to quantify the frequency of RSV testing during LRTI-related hospitalizations of older adults to inform interpretation of incidence estimates. Methods Administrative and billing data for hospitalizations of adults aged ≥ 65 years with a primary or secondary diagnosis of LRTI during the 2016–2019 RSV seasons (October–April) were extracted from the US all-payer Premier Healthcare Database (PHD). Billing codes identified RSV tests administered during eligible hospitalizations. The proportion of LRTI-related hospitalizations with a billed RSV test was calculated for each hospital in PHD, and summarized descriptively by hospital bed size, teaching status, and population served. Results Most of the 937 study hospitals performed RSV testing infrequently during LRTI hospitalization; median percentage of LRTI hospitalizations with RSV testing was 4.3%, and 78.4% of hospitals performed RSV testing in less than 25% of LRTI-related hospitalizations. RSV testing varied extensively by hospital type. Median percentage tested was significantly higher for hospitals with ≥ 200 beds (9.1%) versus < 200 beds (1.6%), for teaching (11.0%) versus non-teaching (2.5%) hospitals, and in urban (7.4%) versus rural (0.7%) settings. The median percentage of RSV testing increased over time, from 0.8% to 6.3% between the 2016/17 and 2018/19 seasons. Conclusion A small proportion of older adults hospitalized with LRTI are tested for RSV in US hospitals. Large variability occurs across hospital types. Consequently, retrospective database analyses likely result in a substantial underestimation of the true RSV-related hospitalization incidence. RSV incidence studies using real-world data need to assess for RSV testing frequency and adjust their results for under ascertainment associated with limited testing.