Table 3.

Poisson regression model used to assess the effect of variables on the risk for paediatric fractures. The variables were selected by a stepwise (forward and backward) variable selection procedure

Variable	Incident rate ratio	95% confidence interval	p-value
Univariate Poisson regression model for all-year weather
Gender-female (categorical)	0.51	0.47 to 0.56	< 0.001
Maximal temperature (°C)	1.01	1.00 to 1.02	0.031
Minimal temperature (°C)	1	1 to 1.012	0.18
Mean temperature (°C)	1.01	1 to 1.014	0.064
Rain level (mm/day)	1	0.99 to 1.01	0.48
Summer vacation (categorical)	0.8	0.69 to 0.93	< 0.01
Multivariate Poisson regression model for all-year weather
Gender-female (categorical)	0.51	0.47 to 0.56	< 0.001
Mean temperature (°C)	1.02	1.01 to 1.02	< 0.001
Summer vacation (categorical)	0.71	0.61 to 0.82	< 0.001
Multivariate Poisson regression model only for days with maximal temperature above 28°C
Gender-female (categorical)	0.51	0.45 to 0.57	< 0.001
Mean temperature (°C)	0.97	0.95 to 0.99	0.02
Summer vacation (categorical)	0.84	0.71 to 0.99	0.03
Poisson regression model only for days with maximal temperature below 28°C
Gender-female (categorical)	0.52	0.47 to 0.58	< 0.001
Mean temperature (°C)	1.04	1.03 to 1.06	< 0.001
Summer vacation (categorical)	-	-	-