Modification of the association between smoking status and severity of coronary stenosis by vitamin D in patients suspected of coronary heart disease

Abstract

Given both smoking and vitamin D are associated with coronary heart disease (CHD) via inflammation and smoking may interfere with the local antiinflammatory effects of vitamin D. We hypothesized that the relationship between smoking and severity of CHD may be modified by vitamin D.A cross-sectional study was conducted. 25-OH vitamin D values were determined in 348 consecutive patients (mean age 62.4 ± 10.5 years; 56.3% male) undergoing coronary angiography at the Heart Center of Chaoyang Hospital affiliated to Capital Medical University between the period of September 2014 and May 2015. We categorized the patients into 2 groups based on 25-OH vitamin D levels, that is, severe hypovitaminosis D (25-OH vitamin D < 10 ng/mL) and higher vitamin D (25-OH vitamin D > = 10 ng/mL). Multivariable logistic regression models were used to estimate odds ratios (ORs) of severe coronary stenosis or higher Gensini score across three smoking status, that is, never smokers, former smokers, and current smokers in severe hypovitaminosis D and higher vitamin D groups, respectively.Of these patients, we identified 212 (60.9%) cases of severe CHD and 161 (46.3%) cases of severe hypovitaminosis D. Multivariable logistic regression model showed the ORs of severe CHD were 1.94 (95% confidence interval [CI]: 0.47, 7.98) for former smokers and 2.62 (95% CI: 0.83, 8.24) for current smokers, compared with never smokers in group with severe hypovitaminosis D (P-trend = 0.005). In contrast, smoking was not found to be significantly associated with severe CHD in group with higher 25-OH vitamin D (P-trend = 0.115). We found a significant interaction between smoking status and vitamin D on presence of severe CHD (P-interaction = 0.015). In terms of Gensini score as a dependent variable, similar results were identified.Our finding indicated the association between smoking and severity of CHD appeared to be substantially stronger among patients with severe hypovitaminosis D as compared with those with higher vitamin D levels. This suggests vitamin D sufficiency may have a protective effect against the damaging effects of smoking on coronary artery. Future cohort studies are warranted to confirm this finding.

Figure 1

ORs and 95% CIs (T-shaped bars) of smokers versus never smokers, for the presence of severe coronary heart disease (white columns) and higher Gensini score (dark columns) according to 25-OH vitamin D levels. Results were adjusted for age, sex, hypertension, diabetes, and HDL cholesterol. Smokers refer to former smokers or current smokers. P_{effectmodification} = 0.045 for severe CHD and = 0.023 for higher Gensini score. CHD = coronary heart disease, CI = confidence interval, HDL = high-density lipoprotein, OR = odds ratio.

Figure 2

ORs and 95% CIs (T-shaped bars) for presence of severe CHD (A) and higher Gensini score (B) according to smoking status and 25-OH vitamin D levels. Dark columns, 25-OH vitamin D > =  10 ng/mL; white columns, 25-OH vitamin D < 10 ng/mL. Results were adjusted for age, sex, hypertension, diabetes, and HDL cholesterol. Nonsmokers with a higher 25-OH vitamin D level had the lowest probability of severe CHD or higher Gensini score and therefore were used as the reference group. Among the other 3 groups, smokers with lower 25-OH vitamin D level had a greatest and significantly risk of severe CHD or higher Gensini score (P < 0.01). Smokers refer to former smokers or current smokers. CHD = coronary heart disease, CI = confidence interval, HDL = high-density lipoprotein, OR = odds ratio.