Multivariable negative binomial regression model for respiratory tract infection hospitalisations
| Characteristic | ARR (95% CI) | p-value |
| Time (per year) | 1.031 (1.028–1.033) | |
| Smoke-free legislation | 0.965 (0.953–0.977) | <0.001 |
| Time since smoke-free legislation (per year) | 0.995 (0.991–0.999) | 0.017 |
| Month | ||
| January | Ref. | |
| February | 0.917 (0.904–0.930) | |
| March | 0.899 (0.887–0.912) | |
| April | 0.682 (0.672–0.693) | |
| May | 0.664 (0.654–0.674) | |
| June | 0.549 (0.540–0.557) | |
| July | 0.579 (0.571–0.588) | |
| August | 0.370 (0.364–0.377) | |
| September | 0.493 (0.486–0.501) | |
| October | 0.777 (0.766–0.789) | |
| November | 1.055 (1.040–1.070) | |
| December | 1.471 (1.451–1.492) | |
| Sex | ||
| Female | Ref. | |
| Male | 1.265 (1.257–1.273) | |
| Age | ||
| 0–4 years | Ref. | |
| 5–9 years | 0.129 (0.127–0.130) | |
| 10–14 years | 0.055 (0.054–0.055) | |
| Region | ||
| Greater London | Ref. | |
| East Midlands | 1.798 (1.772–1.825) | |
| East of England | 1.462 (1.441–1.484) | |
| North East | 2.459 (2.422–2.497) | |
| North West | 2.288 (2.256–2.321) | |
| South East | 1.729 (1.705–1.754) | |
| South West | 1.682 (1.658–1.707) | |
| West Midlands | 1.955 (1.926–1.983) | |
| Yorkshire and the Humber | 2.032 (2.003–2.061) | |
| Urbanisation level | ||
| Rural | Ref. | |
| Urban | 1.008 (1.000–1.016) | |
| Index of Multiple Deprivation | ||
| Quintile 1# | Ref. | |
| Quintile 2 | 1.082 (1.071–1.092) | |
| Quintile 3 | 1.202 (1.191–1.214) | |
| Quintile 4 | 1.336 (1.322–1.349) | |
| Quintile 5¶ | 1.497 (1.481–1.514) |
ARR: admission rate ratio. #: least deprived; ¶: most deprived.