Allostatic load amplifies the effect of blood lead levels on elevated blood pressure among middle-aged U.S. adults: a cross-sectional study

Table 3 Adjusted difference in systolic and diastolic blood pressure by quintiles of blood lead exposure among adults aged 40 to 65 years in the national health and nutritional examination survey, United States, 1999-2008 ^a

	All participants (N = 8,194)		Low allostatic load^b(N = 4,069)		High allostatic load^b(N = 4,125)
	Difference	95% CI	Difference	95% CI	Difference	95% CI
Systolic blood pressure (mm Hg)^c
Pb Exposure
Quintile 1	0	Reference	0	Reference	0	Reference
Quintile 2	−0.79	−2.07, 0.49	−1.08	−2.40, 0.25	0.13	−2.17, 2.44
Quintile 3	0.24	−1.22, 1.71	−0.27	−2.09, 1.55	1.68	−0.65, 4.02
Quintile 4	0.20	−1.26, 1.67	0.20	−1.59, 1.98	0.97	−1.50, 3.44
Quintile 5	0.63	−1.07, 2.33	0.67	−1.24, 2.58	1.60	−0.62, 3.82
Test for trend	P = 0.24		P = 0.21		P = 0.14
Diastolic blood pressure (mm Hg)^d
Pb Exposure
Quintile 1	0	Reference	0	Reference	0	Reference
Quintile 2	0.08	−0.80, 0.97	−0.30	−1.60, 1.01	0.80	−0.51, 2.11
Quintile 3	0.99	0.16, 1.82	1.06	0.03, 2.09	1.23	−0.11, 2.57
Quintile 4	1.17	0.25, 2.08	1.36	0.11, 2.60	1.21	−0.21, 2.63
Quintile 5	1.76	0.75, 2.78	1.79	0.62, 2.95	2.01	0.24, 3.79
Test for trend	P = 0.0001		P = 0.0002		P = 0.02

Abbreviations: CI confidence interval.
^aAdjusted for age, sex, race/ethnicity, education, marital status, smoking status, alcohol consumption, and antihypertensive medication use.
^bLow allostatic load is equal to a score between 7 and 20. High allostatic load is equal to a score between 21 and 35.
^cPb and AL test of interaction for systolic blood pressure: P = 0.75.
^dPb and AL test of interaction for diastolic blood pressure: P = 0.77.

ISSN: 1476-069X