Table 1.

Characteristics of the Rural Population Included in Analyses by Low/Medium/High Nitrate-Nitrogen Levels^a in the Beaver Dam Eye Study

	Nitrate-Nitrogen Levels
	Low N=299	Medium N=287		High N=82
Characteristic	Crude %	Crude %	P valueb	Crude %	P valueb
Age, years
43–54	51.51	41.11	0.07	35.37	0.01
55–64	27.42	36.93		34.15
65–74	17.06	16.03		24.39
≥75	4.01	5.92		6.10
Cancer self-report
No	90.64	91.99	0.44	89.02	0.98
Yes	9.36	8.01		10.98
History of CVDc
No	90.20	89.32	0.93	87.50	0.81
Yes	9.80	10.68		12.50
History of diabetesd
No	94.61	94.06	0.88	90.12	0.27
Yes	5.39	5.94		9.88
Comorbidities of cancer/CVD/diabetes
No	76.43	74.47	0.85	69.23	0.47
Yes	23.57	25.53		30.77
Sunlight exposuree
<1.01 WISY	75.76	78.6	0.38	82.93	0.24
≥1.01 WISY	24.24	21.4		17.07
Ever heavy drinker (≥ 28 drinks/week)
No	86.91	81.82	0.06	75.61	0.002
Yes	13.09	18.18		24.39
Hypertensionf
No	62.54	57.14	0.35	52.44	0.42
Yes	37.46	42.86		47.56
Education status
Not a high school graduate	21.74	21.25	0.43	37.80	<.001
High school graduate or GED	44.15	51.57		52.44
Some college but not including baccalaureate degree	19.40	15.33		6.10
Baccalaureate degree or beyond	14.72	11.85		3.66
Sex
Women	49.50	50.87	0.72	57.32	0.18
Men	50.50	49.13		42.68
Smoking statusg
Never	51.51	45.30	0.09	40.24	0.003
Past	32.11	36.24		31.71
Current	16.39	18.47		28.05

Abbreviations: CVD, cardiovascular disease; GED, general education diploma; WISY, Wisconsin sun years.

^aLow (0–4 ppm), medium (5–9 ppm), and high (≥10 ppm).

^bCompared to low nitrate group; age adjusted for sex, sex adjusted for age, all others adjusted for age and sex.

^cAngina, myocardial infarction, or stroke.

^dSelf report confirmed with treatment, elevated glucose or elevated glycosylated hemoglobin.^14,15

^eEstimated from residential history permitting calculation of WISY at the baseline examination.¹³

^fBlood pressure ≥140/90 mmHg or on antihypertensive medication.

^gNever smoker: <100 cigarettes in his/her lifetime; Past smoker: ≥100 cigarettes in his/her lifetime but not currently smoking; Current smoker: ≥100 cigarettes in lifetime and currently smoking.