Table 3.
Unadjusted and adjusted Cox PH models for RTI-related mortality at 1–4 years in England relative to Sweden in 2003–2012
| Model 1 | Model 2 | Model 3 | |
| Country | |||
| England | 1.58 (1.30 to 1.92) | 1.32 (1.09 to 1.61) | 1.30 (1.07 to 1.59) |
| Sweden (baseline) | 1 | 1 | 1 |
| Birth weight (g) | |||
| 500–1499 | 3.12 (2.02 to 4.83) | 2.99 (1.93 to 4.63) | |
| 1500–2499 | 3.67 (2.78 to 4.84) | 3.50 (2.65 to 4.62) | |
| 2500–3499 | 1.70 (1.43 to 2.02) | 1.66 (1.39 to 1.97) | |
| ≥3500 (baseline) | 1 | 1 | |
| Gestational age (weeks) | |||
| <37 | 0.85 (0.64 to 1.13) | 0.86 (0.65 to 1.15) | |
| 37–38 | 1.18 (1.00 to 1.41) | 1.20 (1.01 to 1.42) | |
| ≥39 (baseline) | 1 | 1 | |
| Sex | |||
| Boy | 0.99 (0.86 to 1.13) | 0.98 (0.85 to 1.13) | |
| Girl (baseline) | 1 | 1 | |
| Congenital anomaly | |||
| Yes | 28.42 (24.58 to 32.86) | 28.39 (24.55 to 32.82) | |
| No (baseline) | 1 | 1 | |
| Maternal age (years) | |||
| <25 | 1.04 (0.86 to 1.25) | ||
| 25–29 | 0.92 (0.76 to 1.11) | ||
| 30–34 (baseline) | 1 | ||
| ≥35 | 0.81 (0.66 to 1.00) | ||
| Quintile of socioeconomic status | |||
| Q1: most deprived | 1.28 (1.02 to 1.60) | ||
| Q2 | 1.08 (0.85 to 1.36) | ||
| Q3 | 1.07 (0.84 to 1.35) | ||
| Q4 | 0.93 (0.73 to 1.19) | ||
| Q5: least deprived (baseline) | 1 | ||
Data are adjusted HR with 95% CI. Each column represents a separate Cox PH model: model 1 was only adjusted for indicator of country with Sweden as baseline, model 2 was additionally adjusted for birth characteristics (birth weight, gestational age and presence of congenital anomalies), and model 3 was further adjusted for socioeconomic factors (socioeconomic status and maternal age).
PH, proportional hazards; RTI, respiratory tract infection.