Järvholm B, Thiringer G
Eur J Respir Dis Suppl. 1980;107:125-9.
It is important to evaluate epidemiological studies of lung cancer even when the smoking habits of the investigated groups are unknown. The increased risk for lung cancer in heavy smokers is known from other studies. Assuming a reference population consisting of 30% non-smokers, 25% ex-smokers, 40% moderate smokers and 5% non-smokers, it can be shown that a more than doubled incidence cannot be explained by differences in smoking habits.
即使被调查群体的吸烟习惯未知，评估肺癌的流行病学研究也很重要。其他研究已证实重度吸烟者患肺癌的风险增加。假设有一个参考人群，其中30%为非吸烟者，25%为已戒烟者，40%为中度吸烟者，5%为重度吸烟者，结果表明，发病率增加一倍以上无法用吸烟习惯的差异来解释。
