Mortality in Relation to Smoking: Ten Years' Observations of British Doctors

In previous papers (Doll and Hill, 1954, 1956) we have described how at the end of October 1951 we sent a short and simple questionary to the 59,600 men and women whose names were on the current British Medical Register and who were then resident in the United Kingdom. In addition to giving name, address, and age, they were asked to say whether (a) they were, at that time, smokers of tobacco, (b) they had previously smoked but had given up, or (c) they had never smoked regularly (which we defined as having never smoked as much as one cigarette a day, or its equivalent in pipe tobacco or cigars, for as long as one year). The smokers and ex-smokers were asked the age at which they had started smoking, the amount that they smoked, and the method by which they smoked either at the time of reply or when they last gave up, and, when appropriate, the age at which they had stopped.