Table 1. Distribution of respiratory syncytial virus hospital admissions, and median and interquartile range of length of stay in hospital according to risk factor, birth cohort study, Scotland, 2009–2015 (n = 5,185 admissions).
| Risk factor | Number of RSV hospital admissions | % of RSV hospital admissions | Median length of stay (IQR) in days | Kruskal-wallis test with ties p-value for difference in median length of stay | Number of bed daysa | % of bed days |
|---|---|---|---|---|---|---|
| Gestational age | ||||||
| < 34 weeks | 268 | 5.2 | 3 (1–6.5) | 0.0001 | 1,640.5 | 10.7 |
| 34–36 weeks | 335 | 6.5 | 3 (1–5) | 1,470.5 | 9.6 | |
| 37–40 weeks | 3,431 | 66.2 | 2 (1–4) | 9,306 | 60.6 | |
| ≥ 41 weeks | 932 | 18.0 | 2 (1–4) | 2,212 | 14.4 | |
| Missing | 219 | 4.2 | 2 (1–4) | 734.5 | 4.8 | |
| Sex | ||||||
| Boys | 2,876 | 55.5 | 2 (1–4) | 0.0628 | 8,580.5 | 55.8 |
| Girls | 2,309 | 44.5 | 2 (1–4) | 6,783 | 44.2 | |
| Chronic condition recorded before 6 months | ||||||
| No | 4,611 | 88.9 | 2 (1–4) | 0.0001 | 12,235 | 79.6 |
| Yes | 574 | 11.1 | 3 (1–6) | 3,128.5 | 20.4 | |
| Postnatal stay in hospital | ||||||
| ≤ 14 days | 4,833 | 93.2 | 2 (1–4) | 0.0001 | 13,553 | 88.2 |
| > 14 days | 215 | 4.2 | 4 (1–7) | 1,458 | 9.5 | |
| Missing | 137 | 2.6 | 2 (0–3) | 352.5 | 2.3 | |
| Season of birth | ||||||
| January–March | 990 | 19.1 | 2 (1–4) | 0.0001 | 3,192 | 20.8 |
| April–June | 977 | 18.8 | 1 (0–3) | 2,394 | 15.6 | |
| July–September | 1,453 | 28.0 | 2 (1–3) | 3,934 | 25.6 | |
| October–December | 1,765 | 34.0 | 2 (1–4) | 5,843.5 | 38.0 | |
| Apgar score at 5 min | ||||||
| 0–7 | 195 | 3.8 | 2 (1–5) | 0.0002 | 995.5 | 6.5 |
| 8–10 | 4,766 | 91.9 | 2 (1–4) | 13,596.5 | 88.5 | |
| Missing | 224 | 4.3 | 2 (1–4) | 771.5 | 5.0 | |
| Birthweight by gestational age | ||||||
| Small for gestational age | 486 | 9.4 | 2 (1–4) | 0.7877 | 1,665.5 | 10.8 |
| Right for gestational age | 3,957 | 76.3 | 2 (1–4) | 11,501 | 74.9 | |
| Big for gestational age | 484 | 9.3 | 2 (1–4) | 1,377.5 | 9.0 | |
| Missing | 258 | 5.0 | 2 (1–4) | 819.5 | 5.3 | |
| Number of siblings (parity) | ||||||
| None | 1,547 | 29.8 | 2 (0–3) | 0.0001 | 4200 | 27.3 |
| 1 | 1,995 | 38.5 | 2 (1–4) | 5,703.5 | 37.1 | |
| ≥ 2 | 1,435 | 27.7 | 2 (1–4) | 4,900 | 31.9 | |
| Missing | 208 | 4.0 | 1 (0–3) | 560 | 3.6 | |
| Maternal smoking during pregnancy | ||||||
| No | 3,471 | 66.9 | 2 (1–4) | 0.0021 | 9862 | 64.2 |
| Yes | 1,246 | 24.0 | 2 (1–4) | 4,201.5 | 27.3 | |
| Missing | 468 | 9.0 | 2 (0–3) | 1,300 | 8.5 | |
| Maternal age | ||||||
| < 20 years | 313 | 6.0 | 2 (1–4) | 0.1589 | 981.5 | 6.4 |
| 20–29 years | 2,478 | 47.8 | 2 (1–4) | 6,995.5 | 45.5 | |
| 30–39 years | 2,076 | 40.0 | 2 (1–4) | 6,280.5 | 40.9 | |
| ≥ 40 years | 150 | 2.9 | 2 (1–5) | 631.5 | 4.1 | |
| Missing | 168 | 3.2 | 2 (0–3.5) | 474.5 | 3.1 | |
| SIMD quintile | ||||||
| 1 Most deprived | 1,485 | 28.6 | 2 (1–4) | 0.3251 | 4,820.5 | 31.4 |
| 2 | 1,117 | 21.5 | 2 (1–4) | 3,416 | 22.2 | |
| 3 | 945 | 18.2 | 2 (1–4) | 2,679.5 | 17.4 | |
| 4 | 888 | 17.1 | 2 (1–4) | 2,501 | 16.3 | |
| 5 Least deprived or missingb | 750 | 14.5 | 2 (1–5) | 1,946.5 | 12.7 | |
| Incomplete infant vaccination at 6 monthsc | ||||||
| No | 2,125 | 80.3 | 1 (0–3) | 0.005 | 5,053.5 | 77.4 |
| Yes or missingb | 520 | 19.7 | 2 (0–4) | 1,475 | 22.6 | |
IQR: interquartile range; RSV: respiratory syncytial virus; SIMD: Scottish Index of Multiple Deprivation.
a To calculate bed days, children with a length of stay of 0 days were allocated 0.5 bed days.
b Fewer than five children had a missing value.
c Including RSV admissions occurring after 6 months of age only. Total number of admissions: 2,645. Total bed days: 6,528.5.
The 5,185 admissions were in 169,726 children, with total of 15,363.5 bed days.