The Association of Agent Orange Exposure with the progression of monoclonal gammopathy of undetermined significance to multiple myeloma: a population-based study of Vietnam War Era Veterans

Table 1 Baseline characteristics of the analytic cohort of MGUS patients stratified by AO exposure status

	Exposure status^†				Total	P-value^‡
	High	Medium	Low	Unexposed	Total	P-value^‡
N	292	2314	245	7996	10,847
%	2.7	21.3	2.3	73.7	100.0
Gender (%)						< .0001
F	0.0	0.04	0.0	2.3	1.7
M	100.0	99.96	100.0	97.7	98.3
Race (%)						< .0001
Black	33.6	30.3	26.5	38.7	36.5
White	66.4	69.7	73.5	61.3	63.5
BMI at MGUS (%)						< .0001
Underweight	1.0	1.0	0.0	1.7	1.5
Normal weight	19.5	16.9	19.6	21.4	20.4
Overweight	34.9	36.4	31.0	33.7	34.3
Obese	44.5	45.6	49.4	43.2	43.9
M-spike (%)						0.088
< 1.5 g/dL	73.6	74.6	74.7	71.8	72.5
> = 1.5 g/dL	4.1	5.1	4.9	6.3	6.0
Missing	21.7	19.3	20.6	21.9	21.5
Ig subtype (%)						0.844
A	14.7	13.7	12.2	14.0	13.9
G	85.3	86.3	87.8	86.0	86.1
Age at MGUS Diagnosis (year)						< .0001
Median	71.7	68.6	66.9	68.7	68.7
IQR (Q1–Q3)	67.2–74.9	64.6–71.6	63.3–69.2	64.3–73.0	64.4–72.6
Charlson Comorbidity score						0.004
Mean	2.4	1.8	2.0	2.0	2.0
Std	3.0	2.6	2.9	2.8	2.8
Ever served in Army during Vietnam Era (%)						< .0001
No	52.1	33.4	39.6	44.5	42.2	52.1
Yes	48.0	66.6	60.4	55.5	57.8	48.0
Ever served in Marine Corps during Vietnam Era (%)						< .0001
No	81.5	84.8	84.1	90.2	88.6
Yes	18.5	15.2	15.9	9.9	11.4
Ever served in Air Force during Vietnam Era (%)						< .0001
No	86.0	91.4	85.3	82.8	84.8
Yes	14.0	8.6	14.7	17.3	15.3
Ever served in Navy during Vietnam Era (%)						< .0001
No	79.8	90.0	88.6	83.0	84.5
Yes	20.2	10.0	11.4	17.0	15.5
Outcome (%)						< .0001
Progression	9.6	7.3	6.1	7.4	7.4
Death without progression	41.1	31.2	35.5	41.9	39.4
Censored	49.3	61.5	58.4	50.7	53.1

^†High exposure was during 1/9/1962–11/30/1965, medium exposure was during 12/1/1965–12/31/1970, and low exposure was during 1/1/1971–5/7/1975. The reasoning for this stratification was that the herbicidal agents used in the first time period had the highest levels of TCDD, followed by the second time period. The last time period was when the herbicidal agents were no longer used, but the toxicity may linger [3, 4]
^‡Chi-square tests were conducted to compare percentages for categorical variables, t-tests were used to compare means for continuous variables, and Kruskal–Wallis test was used to compare medians
Ig immunoglobulin, IQR interquartile range, MGUS monoclonal gammopathy of undetermined significance, BMI body mass index, M-spike monoclonal spike

ISSN: 1756-8722