Table 5.

Summary of final multivariable Cox regression analyses relating risk of death and illness features

	Variable	Hazard Ratio [95% confidence interval]	P
Initial Cox regression model with backwards-stepwise selection*	Clinical subgroup (JDM vs. JPM/JCTM)	4.8 [1.2, 19.6]	0.03
	Illness severity at onset	5.1 [1.4, 17.9]	0.01
	Age at diagnosis	1.1 [0.98, 1.3]	0.09
Final Cox regression model	Clinical subgroup (JDM vs. JPM/JCTM)	8.6 [2.5, 30.2]	0.001
	Illness severity at onset	5.7 [1.6, 19.5]	0.006

Abbreviations. JDM = juvenile dermatomyositis; JPM = juvenile polymyositis; JCTM = juvenile myositis associated with an underlying connective tissue disease.

^*Multivariable Cox regression model began with clinical subgroup (JDM vs. JPM/JCTM), illness severity at onset, age at diagnosis, weight loss and delay to diagnosis before backwards-stepwise selection; 308 patients were included in the model.