Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX6-131
Table AX6-5.1 (cont’d). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period Study Description Pb Measurement Findings, Interpretation
United States
Cheng et al. (2001)
U.S.-Boston,
Normative Aging
Study (VA)
1991-1997
833 males (~97% white), avg age
(SD):
65.5 (7.2) Normotensive subjects,
N = 337
68.3 (7.8) Borderline hypertensive
subjects, N = 181
67.9 (6.8) Definite hypertensive
subjects, N = 314
474 males with no history of
hypertension at first measurement,
returning up to 6 yrs later for
hypertension study.
Linear multiple regression models of
blood pressure and Cox proportional
hazard models of new cases of
hypertension after up to 7 yrs, with
one group of covariates forced into
models based on biological
plausibility and another group
forced based on significant
univariate or bivariate results or
>20% effect modification of Pb
variable coefficient in multiple
models. Linear blood Pb, tibia Pb,
and patella Pb forced in separate
models.
Arithmetic mean (SD) blood
Pb:
5.9-6.4 µg/dL (3.7-4.2),
depending on hypertension
group (only data shown).
Multiple regression models of blood pressure always included age, agesquared,
BMI, family history of hypertension, daily alcohol consumption,
and daily calcium consumption. Increasing tibia Pb concentration was
associated with increased systolic blood pressure (diastolic not addressed) in
baseline measurements in subjects (n = 519) free from definite hypertension
(systolic >160 mm Hg, diastolic >95 mm Hg, or taking daily antihypertensive
medication). Each increase of 10 µg/g tibia Pb concentration was associated
with an increase in systolic blood pressure of 1.0 mm Hg (95% CI: 0.01,
1.99). Patella and linear blood Pb were not significant.
Cox proportional hazard models always included age, age-squared, BMI, and
family history of hypertension. In follow up (n = 474), only increasing
patella Pb predicted increasing risk of definite hypertension in those
classified as normotensive at baseline. For every 10 µg/g increase in patella
Pb risk ratio increased 1.14 (95% CI: 1.02, 1.28). Combining borderline
hypertension (systolic 141-160 mm Hg or diastolic 91-95 mm Hg) with
definite hypertension (n = 306), the relative risk ratio of becoming a
combined hypertensive associated with a 10 µg/g increase in patella Pb was
1.23 (95% CI: 1.03, 1.48). Linear blood Pb and tibia Pb were not
significant.
Linear blood Pb is not indicated for blood pressure models due to strong
likelihood of significant residual heteroscedasticity and non-normality.
Relatively small sample size may have prevented tibia blood Pb significance
in the Cox proportional hazard models.