Cardiovascular disease risk factors in relation to smoking behaviour and history: a population-based cohort study

Keto J, Ventola H, Jokelainen J, et al.
Open Heart. 2016 Jul 12;3(2):e000358

Background

Cigarette smoke is a major risk factor for cardiovascular disease (CVD) and mortality. Other risk factors are high blood glucose, physical inactivity, obesity and elevated cholesterol levels. These risk factors are also associated with smoking [1]. However, an increasingly high number of people smoke [2]. Smoking is more common among men and lower socioeconomic classes. Men also have a 2-5 times higher risk of CVD [3,4].

For this research, the prospective population-based Northern Finland Birth Cohort 1966 study sample had been used, including over 5000 well-characterised individuals.
For each gender separately, CVD risk factors were related to smoking behaviour in people at the age of 46. Smoking was categorized as smokers or non-smokers, but also further subdivided into current smokers (n=1408, smoking 2-7 days a week), individuals who had quit smoking recently (n=121), those who smoked at least 1 year but quit a least 6 months ago (n=1401, former smokers) and people who had never smoked (n=3044).

Main results

• BMI and waist circumference were higher for smokers than for people who had never smoked (P<0.001 for both men and women).
• Total cholesterol (P<0.028) and triglyceride levels (P<0.001) were higher for currently smoking men, than for men who had never smoked (5.6 and 5.5 mmol/L resp. for total cholesterol and 1.7 and 1.4 mmol/L resp. for triglycerides). Current smoking women had higher LDL-c and triglycerides and lower HDL-c than never-smokers (LDL-c 3.34 and 3.22 mmol/L resp. P=0.002, triglycerides 1.2 and 1.0 mmol/L resp. P<0.001 and HDL-c 1.58 and 1.69 mmol/L resp. P<0.001).
• Systolic blood pressure (SBP) for men was 127.1, 126.4, 129.5 and 128.1 mmHg for current smokers, recent quitters, former smokers and never-smokers resp. This was 86.3, 86.1, 87.8 and 85.9 mmHg for diastolic blood pressure (DBP) resp. Differences in SBP and DBP were significant for former smoking men compared to men of all other smoking categories (SBP P<0.001 and DBP P<0.011). In women, never-smokers had the highest SBP (P=0.016); SBP was 117.5, 116.8, 117.5 and 119.1 mmHg for current smokers, recent quitters, former smokers and never-smokers resp. There was no difference is DBP for women.
• Type 2 diabetes was less common in men who had never smoked (P<0.0001) but this trend was not observed for women (men: 4% current smokers, 0% recent quitters, 4.2% former smokers and 1.8% never-smokers).

• The Framingham CVD risk scores for current smoking men, recent quitters, former smokers and men who had never smoked were 14.7, 7.4, 8.1 and 7.5% respectively (P<0.001 compared to current smokers). For women, this was 5.9, 3.0, 3.2 and 3.3% (P<0.001 compared to current smokers) respectively.
• Also the SCORE equation showed a higher risk of a fatal cardiovascular event for smokers (both genders, P<0.001).

Conclusion

Many risk factors were elevated among smokers in comparison with never-smokers or to the group who had quit smoking. However, these differences were modest and are not likely to have major clinical implications. Furthermore, the differences in risk factors between former smokers and never-smokers were that small, that smoking cessation could have a great significance in reducing cardiovascular morbidity and mortality at the age of 46.

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References

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