Figure 5.
Forest plot of annual respiratory syncytial virus (RSV)–associated hospitalization rates per 1000 among US infants by study type and age group (n = 31). The x-axis represents the annual rates of RSV-associated hospitalization per 1000. Inverse-variance weighting, which weights each study on the inverse of the variance of each study effect estimate (ie, larger weights for studies with smaller standard errors), was used to combine individual study estimates. Active surveillance studies were prospective and required etiologic testing and confirmation of RSV. All active prospective surveillance study estimates came from the Centers for Disease Control and Prevention New Vaccines Surveillance Network program and identified RSV via culture and reverse-transcription polymerase-chain reaction of nasal and throat swab samples taken from children hospitalized with acute respiratory infection in 1 of the study catchment sites. Retrospective medical record review (MRR) studies were based on passive surveillance of available standard-of-care medical and laboratory records. Two retrospective MRR studies [17, 18] adjusted their estimated RSV incidence rates upward to account for the estimated number of cases that were missed based on standard-of-care diagnostic and testing practices (ie, missed case ascertainment in passive surveillance). International Classification of Diseases, Ninth Revision (ICD-9) code studies were retrospective analyses of administrative claims data based on RSV-specific ICD-9 codes (466.11, 480.1, and 079.6). Model-based estimates supplemented RSV-specific ICD-9 claims data with etiologic surveillance data. Abbreviation: CI, confidence interval.