Table 4.

Adjusted odds ratios (95% CI) for incident CHD according to the combined categories of plasma metal levels.

Metals	$n$ (case/control)	Odds ratio (95% CI)a	p-Interactionb
Selenium-Arsenic
$\text{Low}\mathrm{Se}+\text{Low}\mathrm{As}$	369/426	1.00	0.52
$\text{Low}\mathrm{Se}+\text{High}\mathrm{As}$	506/384	1.37 (1.10, 1.69)
$\text{High}\mathrm{Se}+\text{Low}\mathrm{As}$	311/384	0.86 (0.68, 1.08)
$\text{High}\mathrm{Se}+\text{High}\mathrm{As}$	435/427	1.05 (0.85, 1.32)
Selenium-Titanium
$\text{Low}\mathrm{Se}+\text{Low}\mathrm{Ti}$	435/474	1.00	0.29
$\text{Low}\mathrm{Se}+\text{High}\mathrm{Ti}$	440/336	1.33 (1.07, 1.66)
$\text{High}\mathrm{Se}+\text{Low}\mathrm{Ti}$	280/336	0.87 (0.69, 1.11)
$\text{High}\mathrm{Se}+\text{High}\mathrm{Ti}$	466/475	0.98 (0.79, 1.22)

Note: Metals that were significant in the multiple-metal model ($p<0.05$) were included in the combined effect analysis. As, Arsenic; Se, Selenium; Ti, Titanium.

^aThe multivariable-adjusted model included the combined categories of metals levels [Low Se $\le 67.48\mathrm{\mu }\mathrm{g}/\mathrm{L}$ ($\mathrm{Q}1+\mathrm{Q}2$), high Se $\ge 67.48\mathrm{\mu }\mathrm{g}/\mathrm{L}$ ($\mathrm{Q}3+\mathrm{Q}4$). Low As $\le 1.96\mathrm{\mu }\mathrm{g}/\mathrm{L}$ ($\mathrm{Q}1+\mathrm{Q}2$), high As $\ge 1.96\mathrm{\mu }\mathrm{g}/\mathrm{L}$ ($\mathrm{Q}3+\mathrm{Q}4$). Low Ti $\le 29.14\mathrm{\mu }\mathrm{g}/\mathrm{L}$ ($\mathrm{Q}1+\mathrm{Q}2$), high Ti $\ge 29.14\mathrm{\mu }\mathrm{g}/\mathrm{L}$ ($\mathrm{Q}3+\mathrm{Q}4$)], BMI, smoking status, pack year, alcohol intake status, education, physical activity, hypertension, hyperlipidemia, family history of coronary heart disease, diabetes, and eGFR.

^bp-Interaction was the likelihood ratio test p-values comparing the fit of models with jointly categorized exposures to corresponding models with lower-order terms for each metal only.