Interaction between blood lead level and chronic obstructive pulmonary disease (COPD) on risk of heart attack or stroke: USA NHANES, 2013-2014

Background: Among all risk factors of cardiovascular disease (CVD), lead is associated with cardiovascular mortality. Besides CVD, blood lead level is also related to the chronic obstructive pulmonary disease (COPD). The inter-relationship of CVD, blood lead level and COPD are not yet studied. Objective: The aim of this study is to examine the interaction of COPD and blood lead level on the occurrence of heart attack. Methods: This analyzed data is from the 2013-2014 NHANES. The final analysis included 5736 adults. Survey logistic regression models were built to control confounders. We computed adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). Results: A significant interaction (OR = 0.26, CI = 0.12, 0.56) between COPD and blood lead level on the occurrence of heart attack was observed. Those who had COPD were 4.05 times more likely to have heart attack than those who did not have COPD for 1 mu g/dL increase in blood lead level. Similarly, a significant interaction between COPD and lead was found for the occurrence of stroke (OR = 0.44, CI = 0.19,1.00), leading to 1.15 times likely to have stroke than those who did not have COPD for 1 mu g/dL increase in blood lead level. For the combined outcome, OR = 0.28 with CI = (0.14, 0.57). Conclusions: The low lead level today means more effect of COPD on the occurrence of heart attack and stroke. More studies required to understand the pathways of the association of COPD, CVD and lead due to their shared risk factors.