Table 2.

Associations Between Log₂-Transformed Blood Lead Level and ALS Risk, Veterans With ALS and Lead Exposure Study, United States, 2003–2007

	No. of Controls	%	All Cases (n = 184)						ALS Cases (n = 151)
			No. of Cases	%	ORa	95% CI	ORb	95% CI	No. of Cases	%	ORa	95% CI	ORb	95% CI
Overall	194	100	184	100	2.6	1.9, 3.7	1.9	1.3, 2.7	151	82	2.5	1.8, 3.4	1.8	1.2, 2.5
Stratified by PINPc
PINP ≤34.45 μg/L	97	50	90	49	2.4	1.5, 3.7	1.5	0.9, 2.6	76	41	2.2	1.4, 3.5	1.4	0.8, 2.3
PINP >34.45 μg/L	97	50	90	49	2.9	1.8, 4.8	2.3	1.4, 3.9	72	39	2.7	1.6, 4.5	2.2	1.3, 3.8
Stratified by CTXc
CTX ≤0.32 ng/mL	95	49	31	17	3.0	1.5, 5.8	2.8	1.4, 5.5	28	15	2.8	1.4, 5.5	2.6	1.3, 5.3
CTX >0.32 ng/mL	99	51	149	81	2.0	1.3, 2.9	1.6	1.1, 2.4	120	65	1.9	1.3, 2.8	1.5	1.0, 2.3
Stratified by ALAD genotyped
ALAD1	156	80	157	85	2.7	1.9, 3.8	2.0	1.3, 2.9	127	69	2.5	1.7, 3.6	1.8	1.2, 2.7
ALAD2	32	16	25	14	1.9	0.8, 4.5	1.2	0.4, 3.1	23	12	1.9	0.8, 4.6	1.1	0.4, 3.1

Abbreviations: ALAD, δ-aminolevulinic acid dehydratase gene; ALS, amyotrophic lateral sclerosis; CI, confidence interval; CTX, C-terminal telopeptides of type 1 collagen; OR, odds ratio; PINP, procollagen type 1 amino-terminal peptide.

^aAdjusted for age (continuous; age at diagnosis for cases and age at interview for controls); in analyses stratified by PINP and CTX, 4 cases (3 with ALS) were excluded because of missing PINP/CTX level.

^bAdjusted for age and log₂-transformed CTX level; 4 cases (3 with ALS) were excluded because of missing CTX level.

^cCategorizations were made at the medians of PINP/CTX among the controls; 4 cases (3 with ALS) were excluded because of missing PINP/CTX level.

^dTwo cases and 6 controls were excluded because of missing ALAD data.