Older adults and infants were found to have the highest mortality and hospitalization rates of respiratory syncytial virus (RSV).
Acute lower respiratory infection (ALRI) has been mostly caused by RSV in young children and older adults. The mortality burden of the infection is high especially in low- and middle-income countries. RSV is tested in different ways across different ages, and young children are more likely to be tested for RSV compared with adults. This poses a challenge in estimating the disease burden of RSV in older adults.
The review aimed to report hospitalization and mortality burdens in RSV for all ages.
The systematic review started with a database search of Medline, Embase, and Global Health for studies that were published between January 1, 1995, and December 31, 2021. Studies that reported hospitalizations and mortality that were associated with RSV were searched with the search being limited to primary literature published in the English language.
Studies that reported data for those infected with RSV and reported rates for mortality and/or hospitalization were included. Studies were excluded if they investigated RSV as a co-infection instead of main outcome, did not clearly and consistently define RSV cases, were case reports or reviews, or focused on subjects with special medical conditions.
All results were split into age groups of aged less than 1 year, 1 to 4 years, 5 to 17 years, aged 18 to 49 years, 50 to 64 years, 65 to 74 years, and 75 years or more; a binary grouping of 0 to 4 years and 65 years or more was also used. All results had their median and IQR calculated.
There were 32 studies included overall and 17 studies included in the meta-analysis. There were 19 studies that reported hospitalization rate, of which 14 had a case definition of acute respiratory infection (ARI). There were 17 studies that reported mortality estimates, including 13 that had all-cause mortality; 4 studies had both hospitalization and mortality estimates. Studies from high-income countries made up the majority of the included studies (26 of 32). There were 3 “high quality” studies, 18 of “moderate quality,” and 11 of “low quality.”
The highest rate of hospitalization in high-income countries was found in infants less than 1 year old, with a median of 2227.7 per 100,000 (IQR, 2029.5-2640.4) for circulatory and respiratory diseases, a median of 2235.7 (IQR, 1779.1-3552.5) for ARI, a median of 3560.0 (IQR, 3012.5-6626.1) for ALRI, and a median of 157.5 (IQR, 68.5-199.5) for pneumonia and influenza (P&I). The lowest rate of hospitalization was found in those aged 18 to 49 years for P&I and ALRI and in 5 to 17 years for ARI.
The hospitalization rates for those aged less than 1 year, 1 to 4 years, and 5 to 17 years were higher in upper middle-income countries compared with high-income countries. Recorded hospitalization rates saw a decreasing trend as the patient increased in age.
The rates of mortality for RSV had a U-shape age pattern that was similar to that of the hospitalization rates. The highest mortality was found to be in older adults aged 65 years and older, specifically in those aged 75 years and older, and followed by infants who were less than 1 year old. All-cause and P&I mortality associated with RSV for adults aged 65 years and older had a median rate of 70.1 per 100,000 (IQR, 46.5-221.5) and a median of 36.6 (IQR, 21.9-51.3) respectively. The lowest mortality rate was found in those aged 5 to 17 years and 18 to 49 years.
Heterogeneities in the studies could not be accounted for. Finer age bands with the first year of life were not reported in many studies. The majority of the studies were conducted in high-income countries, which left low- and middle-income countries underrepresented. Age-specific RSV activity data was not included in many studies. All included studies only covered RSV infections from prior to the COVID-19 pandemic.
The researchers concluded that their review provided an analysis of the evidence on mortality and hospitalizations associated with RSV. Older adults and infant children were at most risk of both hospitalization and mortality due to RSV.
Cong B, Dighero I, Zhang T, Chung A, Nair H, Li Y. Understanding the age spectrum of respiratory syncytial virus associated hospitalization and mortality burden based on statistical modelling methods: a systematic analysis. BMC Med. 2023;21:224. doi:10.1186/s12916-023-02932-5