Key result
Smoking 20 cigarettes per day compared to no smoking increased the absolute risk of coronary heart disease by 1.89%, with no meaningful mediating effect via body weight changes.
Why the study?
Natural direct and indirect effects cannot generally be estimated unbiasedly when time-varying confounders are affected by prior exposure and a time-varying mediator.
Does cigarette smoking increase incident coronary heart disease, and is this effect mediated by body weight in participants from the Multi-Ethnic Study of Atherosclerosis?
Cohort
Does cigarette smoking increase incident coronary heart disease, and is this effect mediated by body weight in participants from the Multi-Ethnic Study of Atherosclerosis?
Smoking increases the risk of incident coronary heart disease, and this effect is direct rather than being meaningfully mediated by changes in body weight.
Answers are grounded in this paper and cite their sources.
Smoking associated with higher CHD risk independent of weight; leaves open causal mediation questions in multi-ethnic cohorts.
BACKGROUND: In settings in which there are time-varying confounders affected by previous exposure and a time-varying mediator, natural direct and indirect effects cannot generally be estimated unbiasedly. In the present study, we estimate interventional direct effect and interventional indirect effect of cigarette smoking as a time-varying exposure on coronary heart disease while considering body weight as a time-varying mediator. METHODS: To address this problem, the parametric mediational g-formula was proposed to estimate interventional direct effect and interventional indirect effect. We used data from the Multi-Ethnic Study of Atherosclerosis to estimate effect of cigarette smoking on coronary heart disease, considering body weight as time-varying mediator. RESULTS: Over a 11-years period, smoking 20 cigarettes per day compared to no smoking directly (not through weight) increased risk of coronary heart disease by an absolute difference of 1.91% (95% CI: 0.49%, 4.14%), and indirectly decreased coronary heart disease risk by -0.02% (95% CI: -0.05%, 0.04%) via change in weight. The total effect was estimated as an absolute 1.89% increase (95% CI: 0.49%, 4.13%). CONCLUSION: The overall absolute impact of smoking to incident coronary heart disease is modest, and we did not discern any important contribution to this effect relayed through changes to bodyweight. In fact, changes in weight because of smoking have no meaningful mediating effect on CHD risk.
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Mokhayeri et al. (2022) conducted a cohort in Coronary heart disease. Cigarette smoking vs. No smoking was evaluated on Incident coronary heart disease (Absolute increase 1.89%, 95% CI 0.49%, 4.13%). Smoking 20 cigarettes per day compared to no smoking increased the absolute risk of coronary heart disease by 1.89%, with no meaningful mediating effect via body weight changes.
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