What's the cardiovascular risk of light smoking? Does a light smoker only incur a proportionally small fraction of the risk of a heavy smoker?
What I've found so far is the following:
According to this meta-analysis, the risk of cigarettes smoked by day (CPD) isn't linearly correlated to cardiovascular risk, instead it follows a much steeper curve for low CPD and then flattens out.
Smokers who cut down the number of cigarettes they use can benefit from large reductions in the risk of cancer and some benefits on cardiovascular disease. However, smoking only one to five cigarettes per day is associated with a risk of coronary heart disease and stroke that is substantially higher than many health professionals or smokers recognise (as much as half the risk of smoking 20 per day).
That it is that nonlinear is a quite surprising result.
But, the problem is… there's also the famous INTERHEART study. And by this one, we find at least for acute myocardial infarction (AMI) a linear risk-CPD-dependency:
So what is it? Can those very different results be explained/harmonized? Has a firm consensus been reached regarding the correlation (cardiovascular disease) – CPD?