- R Doll,
- R Peto
A total of 20540 male doctors who replied to a questionnaire on their smoking habits that was sent to them on 1 November 1951, and who were aged 35 years and over, were classified according to their occupation as listed in the Medical Directory for 1952 and followed up until 1 November 1971. Examination of the mortality rates in 11 occupational groups showed gross heterogeneity for smoking-related diseases but not for all other diseases grouped together. On average, general practitioners smoked 37% more cigarettes than did hospital physicians and surgeons and the overall death rates among general practitioners were about 23% higher than among physicians and surgeons of similar ages. This excess death rate was chiefly accounted for by a 38% excess mortality from smoking-related diseases such as lung cancer, chronic bronchitis, and ischaemic and pulmonary heart disease. The few other statistically significant associations between occupation and disease were thought to be due either to chance or to the effect of the disease on the choice of specialty.