Table 2.

Multivariate analysis results: factors associated with CPAP failure

	aRR for CPAP failure (95%CI)	p
1st model
Gestational age	0.62 (0.51–0.76)	< 0.0001
Incomplete or no prenatal steroids	3.2 (1.07–9.6)	0.037
Pre-eclampsia	3 (0.7–12.2)	0.123
LBC	0.99 (0.9–1.004)	0.218
2nd model (with interaction term)
LBC*Gestational age	1.001 (0.99–1.003)	0.213

Two models are presented: a first model including covariates with p < 0.20 at the univariate analysis and a second one also including an interaction term “LBC^*Gestational age”. Goodness-of-fit is good for both models (p < 0.001, Omnibus test)