. 2017 Sep 27;125(9):097023. doi: 10.1289/EHP1115

Table 1.

Demographic and clinical characteristics of participants.

Characteristics	ALS patients ( $n = 917$ )	Controls ( $n = 2,662$ )	p-Value^a
Male, $n$ (%)	560 (61.1)	1,633 (61.3)	0.88
Age, y, median (IQR)^b	63.5 (57.0, 70.1)	63.5 (57.5, 69.7)	0.81
Bulbar site of onset, $n$ (%)	321 (35.0)	—	—
El Escorial classification, $n$ (%)
Definite	166 (18.1)	—	—
Probable	377 (41.1)	—	—
Probable lab supported	215 (23.4)	—	—
Possible	144 (15.7)	—	—
Education, $n$ (%)
Elementary school	74 (8.1)	190 (7.1)	—
Secondary school/high school	603 (65.8)	1,702 (63.9)	0.23
College/university	240 (26.2)	770 (28.9)	—
Premorbid BMI, ${kg / m}^{2}$ , $n$ (%)^c
Underweight ( $< 18.5$ )	30 (3.3)	23 (0.9)	—
Normal weight ( $18.5 - < 25.0$ )	512 (55.8)	1,143 (42.9)	$< 0.001$
Overweight ( $25.0 - < 30.0$ )	300 (32.7)	1,239 (46.5)	—
Obese ( $\geq 30.0$ )	75 (8.2)	257 (9.7)	—
Current smoking, $n$ (%)^d	154 (16.8)	346 (13.0)	0.004
Current alcohol consumption, $n$ (%)^d	699 (76.2)	2,283 (85.8)	$< 0.001$
Area SES, median (IQR)^e	20.0 (18.0, 23.0)	20.6 (18.0, 24.0)	0.03
Urbanization degree, addresses/ ${km}^{2}$ , $n$ (%)^f
Very high ( $\geq 2,500$ )	121 (13.2)	243 (9.1)	—
High ( $1,500 - < 2,500$ )	244 (26.6)	683 (25.7)	—
Moderately ( $1,000 - < 1,500$ )	235 (25.6)	659 (24.8)	$< 0.001$
Low ( $500 - < 1,000$ )	245 (26.7)	755 (28.4)	—
Very low ( $< 500$ )	72 (7.9)	322 (12.1)	—

Note: —, data not available; ALS, amyotrophic lateral sclerosis; BMI, body mass index; SES, socioeconomic status.

^{^a}

p-Values were calculated using chi-square test for categorical variables and the Mann-Whitney U-test for continuous variables.

^{^b}

Age at onset in patients, and age at which questionnaire was completed by controls.

^{^c}

Premorbid, meaning before symptom onset in cases, and at inclusion for controls.

^{^d}

Current, meaning before symptom onset in cases and at study inclusion for controls.

^{^e}

Socioeconomic status is based on area level percentage of high income.

^{^f}

Urbanization degree is based on area level, divided into five categories according to Statistics Netherlands (www.cbs.nl).