Table 1.
Summary of the variables in the association analysis including the amount of data available for each variable.
| Variable of interest | Definition | Available data for children 0–59 months of age, n = 1,096 | N (%)a |
|---|---|---|---|
| Outcome variable | |||
| Need for respiratory support | Treatment with invasive or non-invasive positive pressure ventilation during RSV hospitalization | 1,075 (98.1%) | Yes = 202(19%) |
| Hospitalization > 72 h | Length of stay measured in hours and dichotomized as stay under 72 h or above 72 h. | 978 (89.2%) | >72 h = 317 (28.9%) |
| Demographic risk factors | |||
| Age | In months, by age group | 1,096 (100%) | <3 m = 301 (27%) 3–5 m = 181 (17%) 6–11 m = 170 (16%) 12–23 m = 297 (27%) 24–59 m = 147 (13%) |
| Sex | Biological sex, male or female | 1,096 (100%) | Male = 615 (56%) |
| Siblings | Children <18 years of age, living in the same household | 1,031 (94%) | Yes = 766 (74%) |
| Pets | Daily contact with pet animals | 1,032 (94%) | Yes = 259 (25%) |
| Day-care attendance | Attending nursery-home etc. | 822 (75%) | Yes = 493 (60%) |
| Gestational risk factors | |||
| Maternal age | Maternal age at time of delivery | 1,091 (99.5%) | Mean = 31.0 (SD 4.90) |
| Smoking during pregnancy | Smoking any time during pregnancy | 974 (88.8%) | Yes = 32(3%) |
| Born before peak season | Being born before peak of first RSV season, applies to children <6 months of age | n.a. | |
| Prematurity | Gestational age <32 weeks | 1,090 (99%) | Yes = 29 (3%) |
| Cesarean delivery | Cesarean delivery, planned or acute | 1,091 (99.5%) | Yes = 222 (20%) |
| Multiple gestation | Twins or triplets | 1,096 (100%) | Yes = 56 (5%) |
| Small for gestational age | Birth weight Z-score < −1.28 SD according to sex and gestational age | 1,090 (99%) | Yes = 87 (8%) |
| Comorbidity and dispositions | |||
| No breastfeeding | Never breastfeed | 739 (67.4%) | Yes = 46 (6%) |
| Family history of atopy | History of asthma or atopic disease in first order relatives | 738 (67.3%) | Yes = 125 (17%) |
| Comorbidity | Including trisomy 21, neuromuscular impairment, congenital heart disease, pulmonary disease, BPD, immunodeficiency, and cancer. Conditions identified by ICD-10 codes provided in supp. data | 1,096 (100%) | Yes = 94 (9%) |
| Respiratory support during neonatal period | Treatment with invasive or non-invasive positive pressure ventilation during neonatal period. Not including treatment for RSV disease | 1,096 (100%) | Yes = 84 (8%) |
| Viral Co-detection | Influenza A and B virus, Parainfluenza virus subtype 1-3 and Human metapneumovirus | 1,019 (93%) | Yes = 76 (7%) |
aNumber of positive outcomes for each variable, and N-positive as percentage of the available data.