Association between MR imaging clusters and clinical features in patients with ALS^a

	ALS Population (n = 90)	Cluster 1 (n = 28)	Cluster 2 (n = 51)	Cluster 3 (n = 11)	P Value
Age at onset (median) (IQR) (yr)	57 (50–65)	67 (62–70)	41 (44–54)	46 (45–54)	P = .045^b
					P = .001^c
					P = ns^d
Sex (No. of patients) (male/female)	47:43	9:19	29:22	9:2	P = .035^b
					P = .005^c
					P = ns^d
Site of onset (spinal/bulbar) (No. of patients)	67/23	20/8	36/15	11/0	P = ns^b
					P = .047^c
					P = .039^d
ALS phenotypes: classic/bulbar/flail arm/flail leg/pyramidal/respiratory/PLMN/PUMN (No. of patients)	68/7/0/0/0/0/15/0	25/2/0/0/0/0/1/0	34/5//0/0/0/0/12/0	9/0//0/0/0/0/2/0	P = ns^b
					P = ns^c
					P = ns^d
El Escorial-revised, categories: definite/probable/possible (No. of patients)	22/36/32	12/14/2	8/18/25	2/4/5	P < .001^b
					P = .017^c
					P = ns^d
ODI (median) (IQR) (mo)	10.07 (6.08–19.27)	9.18 (6.08–14.32)	11.73 (6.23–19.53)	8.97 (4.07–19.27)	P = ns^b
					P = ns^c
					P = ns^d
ALSFRS-r (median score) (IQR)	38 (34–42)	34 (31–37)	40 (35–43)	40 (38–43)	P = .001^b
					P < .001^c
					P = ns^d
Progression rate (median) (IQR)	0.83 (0.45–1.38)	1.26 (0.68–2.84)	0.70 (0.29–1,20)	0.80 (0.45–1.12)	P = .002^b
					P = .022^c
					P = ns^d
Long/short survivors (No. of patients)	26/64	3/25	17/34	6/5	P = .032^b
					P = .008^c
					P = ns^d
Survival time from symptom onset to composite outcome (median) (estimated median) (95% CI) (mo)	46.63 (37.95–55.31)	34.5 (22.39 −46.6)	46.63 (35.4–57.87)	72.73 (42.98–102.47)	P = .043^b
					P = .004^c
					P = ns^d

Note:—ns indicates not significant; PLMN, prevalent lower motor neuron; PUMN, prevalent upper motor neuron.
↵a Group differences in the demographic and clinical variables were evaluated using a Mann-Whitney U test for continuous variables and χ² tests for discrete variables. Log-rank tests were used to test for differences in survival between different radiologic clusters.
↵b Cluster 1 versus cluster 2.
↵c Cluster 1 versus cluster 3.
↵d Cluster 2 versus cluster 3.