A0341 Association of office and ambulatory blood pressure with blood lead in workers prior to occupational exposure

Abstract

Objectives: In view of decreasing lead exposure and guidelines endorsing ambulatory above office BP measurement, we re-assessed association of ambulaotry BP with blood lead (BL). Methods: In 236 newly employed men (mean age, 28.6 years) without previous lead exposure not treated for hypertension, office BP was the mean of five auscultatory readings at one visit; 24-h BP was recorded at 15- and 30-minute intervals during wakefulness and sleep; BL was determined by inductively coupled plasma mass spectrometry. Results: Systolic/diastolic office BP averaged 120.0/80.7 mm Hg and the 24 h, awake and asleep BP 125.5/73.6, 129.3/77.9 and 117.6/65.0 mm Hg, respectively. BL averaged 4.5 mcg/dL (IQR, 2.60–9.15 mcg/dL). In multivariable-adjusted analyses, effect sizes associated with BL doubling were 0.79/0.87 mm Hg (P = 0.11/0.043) for office BP and 0.29/ 0.25, 0.60/ 0.10 and 0.40/ 0.43 mm Hg for 24-h, awake and asleep BP (P ≥ 0.33). Neither office nor 24-h ambulatory hypertension were related to BL (P ≥ 0.14). A clinically relevant white-coat effect (WCE; office minus awake BP, ≥20/≥10 mm Hg) was attributable to exceeding the systolic or diastolic threshold in 1 and 45 workers, respectively. With BL doubling, the systolic/diastolic WCE increased by 0.20/0.97 mm Hg (P = 0.57/0.046). Accounting for the presence of a diastolic WCE, reduced the association size of office diastolic BP with BPb to 0.39 mm Hg (95% confidence interval, 0.20 to 1.33; P = 0.15). Conclusion: In conclusion, a cross-sectional analysis of newly hired workers prior to lead exposure identified the WCE as confounder of the association between office BP and BL and did not reveal any association between ambulatory BP and BL.