Public policy is based on results of epidemiological meta-analyses that contradict common sense

EDITOR,—Matthias Egger and George Davey Smith's scepticism about the validity of meta-analyses whose conclusions are contradicted by those of single megatrials1 can be extended to meta-analyses of epidemiological studies whose findings contradict biological common sense. The alleged causative contribution of passive smoking to lung cancer is based, among other things, on a meta-analysis of 10 case-control studies and three prospective studies that showed a highly significant 35% increased risk among non-smokers living with smokers …