Risk Factors for Severe Respiratory Syncytial Virus Lower Respiratory Tract Infection

Abstract

RSV infection is a leading cause of lower respiratory tract infection, especially in High-risk infants with a history of prematurity, bronchopulmonary dysplasia (BPD), congenital heart disease (CHD), neuromusculair impairment, immunodeficiency, and Down syndrome. Host related risk factors that have been identified to be associated with severe RSV related lower respiratory tract infection include young age below 6 months at the beginning of RSV season, multiple birth, male sex, low socioeconomic status and parental education, crowded living conditions, young siblings, maternal smoking and indoor smoke pollution, malnutrition/small for gestational age, family history of atopy or asthma, low cord serum RSV antibody titers, and living at altitude.Risk factors increasing the risk of acquisition of RSV have been identified to be birth before and/or during RSV season, day care attendance, presence of older siblings in school or day-care, and lack of breast feeding. Some of these risk factors are discussed controversially and some of them are found continuously throughout the literature.Given the high cost of RSV prophylaxis, especially for the large population of late preterm infants, algorithms and risk score systems have been published that could identify high-risk infants for treatment with palivizumab out of this gestational age group. Several models reported on an average sensitivity and specificity of 70 percent and, thus, are helpful to identify infants at high risk for severe RSV infection and need for prophylaxis with palivizumab.

Respiratory Syncytial Virus–Associated Hospitalizations Among Children Less Than 24 Months of Age

“…Although recent studies, most of which were retrospective assessments, have consistently shown RSV hospitalizations to be the highest in the first year of life, very few have dissected the exact age of RSV-specific hospitalizations more precisely. [4][5][6][13][14][15][16][17][18][19][20] For example, a retrospective, population-based study from Spain found that among children ,24 months old hospitalized with laboratory-identified RSV, 9% were ,1 month of age, similar to our findings; however, their rate of RSV hospitalizations among infants ,1 month of age was more than twice ours (31 per 1000 vs 13.5 per 1000, respectively). 19 Another study estimated a notably high annual rate of RSV-associated hospitalizations among infants #3 months old, 48.9 per 1000 children, which is more than twice the rate we found.…”

“…27 However, the effect varied according to age and multiple factors associated with crowding. 14,17,29 In our study, the proportion of hospitalized children residing in homes with other children ,5 years old was more than twice that of children living with older children.…”

“…14,15,17,25 Of our children hospitalized with RSV, 10% were preterm, but their risk of hospitalization was not significantly different from that for term infants. We did find lower rates of hospitalization among late-preterm infants, and higher rates among very premature infants, in contrast to other studies.…”

“…7,22 The reported proportions of children with chronic conditions hospitalized with RSV have ranged widely, possibly reflecting the variable underlying populations and study designs. 6,15,17,24 Stockman et al 6 recently found that 12% of RSV-hospitalized children ,12 months old and 2.4% of those 12 to 23 months old had heart disease, chronic neonatal respiratory distress, or prematurity, as determined by RSV ICD-9-CMcoded discharge diagnoses. In comparison, we found that 21% of RSV-hospitalized children ,12 months old and 53% of children 12 to 23 months old had chronic conditions, as determined by medical chart review.…”

“…26 Many studies have examined environmental factors associated with an increased risk of children acquiring RSV disease, especially contact with other children. 12,14,16,17,27,28 A recent review examining the effect of residential crowding on RSV-associated hospitalizations among young children found significant correlations existed with severe disease in studies reporting laboratory-confirmed RSV infections. 27 However, the effect varied according to age and multiple factors associated with crowding.…”