Revisiting The Association Between Environmental Tobacco Smoke Exposure And Lung Cancer Risk
Hackshaw et al. [BMJ 1997;315:980-988] estimated that, in non-smoking women, lung cancer risk rises 23% (95% Cl 14-32%) per 10 cigarettes per day smoked by the hus band and 11% (95% Cl 4-17%) per 10 years exposure. Although we reproduced these estimates approximately, use of later and more appropriate data gave lower val ues : 10% (95% Cl 5-15%) per 10 cigarettes per day and 7% (95% Cl 4-11%) per 10 years. Among the reasons Hackshaw et al.  reported higher risks are failure to consider studies reporting results only as exposed/unex posed and substantial overweighting of results from one study. Extended analysis revealed that a linear model fits the data as well as the exponential model of Hackshaw et al.  in the observed range, but yields more plausi ble risk estimates at higher doses. In this paper, we also introduce a method to convert dose-response data, re ported only as a set of correlated risk estimates and con fidence intervals, into a form amenable to dose-response summary analyses.