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During the 24,394.21 person-years of follow-up, 889 deaths, including 192 (21.60%) CHD deaths, were recorded. The adjusted death rate was 3,644 per 100,000 person-years over an observed mean person-years of 19.24. At baseline, the subjects in this cohort study were all older than 50 years, with a mean age of 62.55 ± 5.19 years. In addition, 363 alive and 16 lost-to-follow-up participants were registered.
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As shown in Table 1, using a Cox proportional hazard model, the results showed that in the univariate analysis, age, BMI, systolic blood pressure, diastolic blood pressure, triglyceride, duration of smoking year, history of hypertension, and diabetes were associated with CHD death. The HR (95% CI) for these factors were 1.122 (1.092–1.152), 1.096 (1.045–1.150), 1.022 (1.015–1.030), 1.020 (1.007–1.033), 1.002 (1.000–1.004), 1.010 (1.001–1.018), 2.664 (1.988–3.570), and 2.736 (1.701–4.403), respectively. After adjusting for age (years), systolic blood pressure, diastolic blood pressure, total cholesterol, triglyceride, alcohol intake, exercise, negative affairs, and past medical history (of CHD, hypertension, cerebral vascular sclerosis, and DM), the HR (95% CI) for BMI and duration of smoking in years were 1.051 (1.000–1.104) and 1.009 (1.000–1.017), respectively.
Variables Univariate analysis Multivariate analysis HR (95% CI) P value aHR (95% CI) P value Age (years) 1.122 (1.092–1.152) < 0.0001 1.108 (1.076–1.142) < 0.0001 Body mass index (kg/m2) 1.096 (1.045–1.150) 0.0002 1.051 (1.000–1.104) 0.0491 Systolic pressure (mmHg) 1.022 (1.015–1.030) < 0.0001 1.012 (1.000–1.024) 0.0472 Diastolic pressure (mmHg) 1.020 (1.007–1.033) 0.0028 0.997 (0.978–1.017) 0.7812 Total cholesterol (mg/dL) 1.002 (0.999–1.005) 0.1925 1.001 (0.997–1.004) 0.7140 Triglyceride (mg/dL) 1.002 (1.000–1.004) 0.0412 1.001 (0.999–1.003) 0.3739 Alcohol intake 1.005 (0.746–1.355) 0.9718 0.902 (0.661–1.231) 0.5157 Exercise 0.756 (0.535–1.068) 0.1125 0.811 (0.570–1.154) 0.2441 Negative affairs 1.312 (0.894–1.926) 0.1655 0.981 (0.661–1.458) 0.9262 Smoking related factors Duration of smoking (years) 1.010 (1.001–1.018) 0.0285 1.009 (1.000–1.017) 0.0574 Duration of quitting smoking (years) 0.998 (0.995–1.001) 0.2024 Cigarettes per day 1.006 (0.991–1.021) 0.4378 Smoking Index 1.000 (1.000–1.001) 0.0862 Family history (Yes/No) Hypertension 1.202 (0.764–1.892) 0.4254 Stroke 1.202 (0.764–1.892) 0.4254 CHD 1.410 (0.904–2.199) 0.1294 Past medical history (Yes/No) CHD 1.857 (1.386–2.488) < 0.0001 1.071 (0.771–1.487) 0.6818 Stroke 1.671 (0.533–5.235) 0.3783 Hypertension 2.664 (1.988–3.570) < 0.0001 1.711 (1.192–2.456) 0.0036 Cerebral vascular sclerosis (CVS) 2.114 (1.481–3.018) < 0.0001 1.314 (0.891–1.937) 0.1677 Hyperlipidemia (HLP) 0.864 (0.356–2.101) 0.7475 Diabetes Mellitus (DM) 2.736 (1.701–4.403) < 0.0001 2.126 (1.301–3.475) 0.0026 Note. Adjusted for age (years), body mass index, systolic pressure, diastolic pressure, total cholesterol, triglyceride, alcohol intake, exercise, negative affairs, duration of smoking years, and past medical history (of coronary heart disease [CHD], hypertension, cerebral vascular sclerosis [CVS], diabetes mellitus [DM]). HR, hazard ratio; CI, confidence interval; aHR, adjusted hazard ratio. Table 1. Risk factors for CHD-related deaths at baseline
Table 2 shows the multivariate results of the categorical variables. Individuals aged ≥ 60 years had a significantly increased risk of mortality compared to those aged ≤ 59 years at baseline (60–64 years, adjusted HR [aHR]: 2.072, 95% CI: 1.393–3.082; 65–69 years, aHR: 3.627, 95% CI: 2.338–5.628; and ≥ 70 years, aHR: 5.787, 95% CI: 3.312–10.111). In addition, risk factors associated with CHD mortality were smoking status with current smokers (aHR: 1.552, 95% CI: 1.074–2.243), and BMI ≥ 28 kg/m2 (aHR: 1.625, 95% CI: 1.024–2.581). The adjusted factors included age, systolic pressure, BMI, total cholesterol, triglyceride, smoking status, alcohol intake, exercise, negative affairs, and past medical history.
Item Number of deaths/
total numberObserved person year/
total observed person yearHR 95% CI P value Age (years) < 60 39/402 744.9/9314.58 Reference 60–64 77/473 1352.8/9248.83 2.072 1.393–3.082 0.0003 65–69 52/250 894.5/4108.92 3.627 2.338–5.628 < 0.0001 ≥ 70 24/143 244.1/1721.87 5.787 3.312–10.111 < 0.0001 Smoking status Never smokers 59/388 1070.5/7982.74 Reference Former smokers 66/461 1165.9/8653.68 0.904 0.622–1.314 0.5966 Current smokers 67/419 1000.0/7757.80 1.552 1.074–2.243 0.0192 BMI (kg/m2) < 18.5 2/39 6.0/590.60 0.648 0.156–2.684 0.5497 18.5–24.0 61/511 1086.7/10056.88 Reference 24.0–28.0 100/587 1643.9/11309.57 1.339 0.966–1.858 0.0798 ≥ 28.0 29/131 499.9/2437.16 1.625 1.024–2.581 0.0395 Systolic pressure (mmHg) < 120 37/300 667.5/6243.15 Reference 120–129 43/381 782.1/7718.01 0.696 0.443–1.094 0.1160 130–139 33/207 520.9/3778.99 1.078 0.661–1.759 0.7636 ≥ 140 79/380 1265.9/6654.06 1.221 0.785–1.899 0.3767 Note. Adjusted for age, systolic blood pressure, body mass index (BMI), total cholesterol, triglyceride, smoking status, alcohol intake, exercise, negative affairs, past medical history (of coronary heart disease [CHD], hypertension, stroke, diabetes mellitus [DM]). HR, hazard ratio; CI, confidence interval. Table 2. Multivariate analysis for risk factors of mortality from CHD at baseline
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Figure 1A presents the Kaplan-Meier survival curves stratified by baseline BMI. Compared with normal BMI subjects, obese subjects (aHR: 1.603, 95% CI: 1.012–2.538) had significantly increased risk of mortality at baseline, after adjusting for age, systolic blood pressure, total cholesterol, triglyceride, smoking index, alcohol intake history, exercise, negative affairs, and past medical history. Figure 1B shows the cumulative survival for CHD with the combined effect of smoking and obesity. Compared with normal BMI and nonsmoking subjects, the HR and 95% CI of the overweight and obesity nonsmokers was 1.936 (1.053–3.561), while those of smokers with overweight and obesity was 2.828 (1.520–5.262) (Table 3 and Table 4).
Figure 1. Comparison of the cumulative survival rates of the different body mass index (BMI) categories, for different smoker, fat, or the combined smoker and fat groups. (A) Comparison of the cumulative survival rates of the different BMI groups; (B) Comparison of the cumulative survival rates of the different smoker, fat, or the combined smoker and fat groups.
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The authors wish to thank the doctors in Xijing Hospital and the staff at the 22 veteran centers for their help in data collection and ensuring that the surveys were successful.
BMI (kg/m2) < 18.5 18.5–24.0 24.0–28.0 ≥ 28.0 < 18.5 1 1.670 (0.399–6.989) 2.094 (0.503–8.724) 2.677 (0.614–11.671) 18.5–24.0 1 1.254 (0.905–1.737) 1.603 (1.012–2.538) 24.0–28.0 1 1.278 (0.835–1.956) ≥ 28.0 1 Note. Adjusted for age, systolic pressure, total cholesterol, triglyceride, smoking index, alcohol intake, exercise, negative affairs, past medical history (of coronary heart disease [CHD], hypertension, stroke, diabetes mellitus [DM]). BMI, body mass index. Table 3. Effect of BMI of CHD related death at baseline
Smoking and fat Never smoker
+ not fatNever smoker
+ fatFormer smoker
+ not fatFormer smoker
+ fatCurrent smoker
+ not fatCurrent smoker
+ fatNever smoker + not fat 1 1.936
(1.053–3.561)1.451
(0.736–2.861)1.435
(0.769–2.678)1.853
(0.959–3.579)2.828
(1.520–5.262)Never smoker + fat 1 0.750
(0.445–1.263)0.741
(0.479–1.148)0.957
(0.582–1.575)1.461
(0.936–2.279)Former smoker + not fat 1 0.989
(0.591–1.655)1.277
(0.723–2.254)1.949
(1.150–3.302)Former smoker + fat 1 1.291
(0.780–2.138)1.971
(1.262–3.078)Current smoker + not fat 1 1.527
(0.923–2.524)Current smoker + fat 1 Note. Adjusted for age, systolic pressure, total cholesterol, triglyceride, alcohol intake, exercise, negative affairs, past medical history (of coronary heart disease [CHD], hypertension, stroke, diabetes mellitus [DM]), fat refers to body mass index (BMI) > 28.0. Table 4. Combined effect of smoking and obesity of CHD related death at baseline (HR and 95% CI)
Combined Effect of Smoking and Obesity on Coronary Heart Disease Mortality in Male Veterans: A 30-year Cohort Study
doi: 10.3967/bes2021.012
- Received Date: 2020-08-20
- Accepted Date: 2020-12-14
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Key words:
- Smoking /
- Obesity /
- Coronary heart disease /
- Combined effect /
- Cohort study
Abstract:
Citation: | SAI Xiao Yong, GAO Feng, ZHANG Wen Yu, GAO Meng, YOU Jing, SONG Yu Jian, LUO Ting Gang, SUN Yuan Yuan. Combined Effect of Smoking and Obesity on Coronary Heart Disease Mortality in Male Veterans: A 30-year Cohort Study[J]. Biomedical and Environmental Sciences, 2021, 34(3): 184-191. doi: 10.3967/bes2021.012 |