Table II.
Multivariate analysis of characteristics associated with home oxygen use.
| Factor | Level | Adjusted relative risk (95% confidence interval) | p value |
|---|---|---|---|
| Antenatal steroids | No | Reference | 0.0294 |
| Yes | 1.11 (1.01, 1.21) | ||
| Maternal hypertension | No | Reference | 0.0007 |
| Yes | 1.13 (1.05, 1.2) | ||
| Gestational age in weeks | 31 | Reference | <0.0001 |
| 30 | 1.13 (1.09, 1.21) | ||
| 29 | 1.07 (1.02, 1.17) | ||
| 28 | 1.18 (1.10,1.32) | ||
| 27 | 1.15 (1.06, 1.28) | ||
| 26 | 1.39 (1.25,1.60) | ||
| 25 | 1.43 (1.27, 1.66) | ||
| 24 or less | 1.49 (1.23, 1.89) | ||
| Sex | Female | Reference | 0.004 |
| Male | 1.09 (1.03,1.16) | ||
| PDA ligation | No | Reference | <0.0001 |
| Yes | 1.23 (1.14, 1.32) | ||
| Total days on ventilator (quartiles) | 4 or less | Reference | <0.0001 |
| 5 – 16 | 1.38 (1.26,1.5) | ||
| 17 – 35 | 1.48 (1.35, 1.62) | ||
| 36 + | 2.02 (1.87,2.15) | ||
| Nitric oxide use | No | Reference | <0.0001 |
| Yes | 1.3 (1.17, 1.42) | ||
| PMA at discharge in weeks | 38 or less | Reference | <0.0001 |
| 39 – 40 | 0.88 (0.88, 0.89) | ||
| 41 – 42 | 0.88 (0.88, 0.89) | ||
| 43 + | 1.05 (0.97, 1.15) | ||
| Discharging NICU CCS level | Community | Reference | <0.0001 |
| Non CCS or | |||
| Intermediate | 1.46 (1.17, 1.65) | ||
| Regional | 1.92 (2.44, 1.52) | ||
| Birth Year | 2008 | Reference | 0.0072 |
| 2009 | 0.95 (0.83, 1.08) | ||
| 2010 | 1 (0.87, 1.12) | ||
| 2011 | 0.86 (0.73, 0.99) | ||
| 2012 | 0.88 (0.75, 1.01) | ||
| 2013 | 0.9 (0.76, 1.03) | ||
| 2014 | 1.05 (0.91, 1.18) | ||
| 2015 | 1.11 (0.97, 1.25) | ||
| 2016 | 0.97 (0.82, 1.12) | ||
| No | Reference | <0.0001 | |
Adjusted relative risk was calculated from odds ratios from mixed logistic regression based on proportion, using the method of Zhang J, Yu KF. What’s the relative risk? A method of correcting odds ratio in cohort studies of common outcomes. JAMA 1998. Abbreviations: PDA, patent ductus arteriosus; PMA, post-menstrual age; BPD, bronchopulmonary dysplasia.