Table 2.
Incidence and incidence rates of RSV-associated ARI, medically attended ARI, and hospitalised ARI in the first year of life
| RSV incidence after imputation*† | RSV incidence before imputation‡ | Cohort size or person-time | Number of hospitalisations or number of ARI episodes | Number of RSV-positive (observed) | |
|---|---|---|---|---|---|
| RSV-associated hospitalisation in total cohort | |||||
| Incidence§ | 1·8% (1·6–2·1) | 1·6% (1·3–1·8) | 9154 infants | 341 infants hospitalised | 143 infants with RSV-associated hospitalisation |
| Incidence rate¶ per 1000 infant-months | 1·6 (1·3–1·8) | 1·3 (1·1–1·6) | 109 507 infant-months | 388 hospitalisations | 145 RSV-associated hospitalisations |
| Medically attended RSV-positive ARI in active surveillance cohort | |||||
| Incidence§ | 14·1% (12·3–16·0) | 13·0% (11·0–15·2) | 993 infants | 683 infants with ARI | 129 infants with medically attended RSV-associated ARI |
| Incidence rate¶ per 1000 infant-months | 12·1 (10·2–14·3) | 11·2 (9·3–13·3) | 11 728 infant-months | 1520 ARI | 131 medically attended RSV-associated ARI |
| RSV-positive ARI in active surveillance cohort | |||||
| Incidence§ | 26·2% (24·0–28·6) | 25·1% (22·4–27·9) | 993 infants | 683 infants with ARI | 249 infants with RSV-associated ARI |
| Incidence rate¶ per 1000 infant-months | 23·7 (21·0–26·7) | 22·3 (19·7–25·2) | 11 728 infant-months | 1520 ARI | 262 RSV-associated ARI |
ARI=acute respiratory infection. RSV=respiratory syncytial virus.
Missing RSV status imputed using multiple imputation based on site, sex, age, and meteorological season at time of hospitalisation or ARI, and missing medical attendance imputed using site, sex, age, meteorological season at time of hospitalisation or ARI and RSV status (observed or imputed).
Outcomes that required imputations included: 50 hospitalisations with missing RSV status, 166 ARI episodes with missing RSV status or missing medical attendance status, and 101 ARI episodes with missing RSV status.
Assuming all missing outcomes were negative.
Incidence as proportion of infants experiencing the event at least once during their first year of life.
Incidence rate as number of events per 1000 infant-months of follow-up.