Table 2.

Median age (years) and interquartile range (IQR) at various diagnostic steps for term and preterm males with Duchenne muscular dystrophy and no family history of dystrophinopathy at birth, MD STARnet

	Preterm births		Term births		P value*
	N	Median age (IQR)	N	Median age (IQR)
Earliest mobility signs/symptoms	30	2.00 (2.16)	294	2.01 (2.67)	0.84
Initial medical evaluation	30	2.59 (2.83)	293	4.01 (3.08)	0.07
First neuromuscular visit	30	4.25 (2.80)	295	5.00 (3.00)	0.23
First abnormal CK test	25	4.17 (2.42)	275	4.92 (3.08)	0.19
DNA test	29	4.87 (3.28)	276	5.65 (3.47)	0.23
Muscle biopsy test	12	3.79 (1.99)	136	5.23 (3.24)	0.18
Definitive diagnosis**	30	4.25 (3.42)	295	4.92 (3.00)	0.26

^*Wilcoxon rank-sum test; IQR = interquartile range; MD STARnet = Muscular Dystrophy Surveillance Tracking and Research Network;

CK = creatine kinase

^**We determined the age at definitive diagnosis to be the minimum value among the age at first abnormal CK, age at MB and age at DNA test