S Parish, R Collins, R Peto, L Youngman, J Barton, K Jayne, R Clarke, P Appleby, V Lyon, S Cederholm-Williams, J Marshall, P Sleight for the International Studies of Infarct Survival (ISIS) Collaborators
Abstract
Objectives - To assess the effects of cigarette smoking on the incidence of non-fatal myocardial infarction, and to compare tar in different types of manufactured cigarettes.
Methods - In the early 1990s responses to a postal questionnaire were obtained from 13,926 survivors of myocardial infarction (cases) recently discharged from hospitals in the United Kingdom and 32,389 of their relatives (controls). Blood had been obtained from cases soon after admission for the index myocardial infarction and was also sought from the controls. 4923 cases and 6880 controls were current smokers of manufactured cigarettes with known tar yields. Almost all tar yields were 7-9 or 12-15 mg/cigarette (mean 7 5 mg for low tar (less than 10 mg) and 13-3 for medium tar (at least 10 mg)). The cited risk ratios were standardised for age and sex and compared myocardial infarction rates in current cigarette smokers with those in non-smokers who had not smoked cigarettes regularly in the past 10 years.
Results - At ages 30-49 the rates of myocardial infarction in smokers were about five times those in non-smokers (as defined); at ages 50-59 they were three times those in non-smokers, and even at ages 60-79 they were twice as great as in non-smokers (risk ratio 6.3, 4.7, 3.1, 2.5, and 1.9 at 30-39, 40-49, 50-59, 60-69, 70-79 respectively; each 2P less than 0.00001). After standardisation for age, sex, and amount smoked, the rate of non-fatal myocardial infarction was 10-4% (SD 5 4) higher in medium tar than in low tar cigarette smokers (2P=0-06). This percentage was not significantly greater at ages 30-59 (16.6% (7.1)) than at 60-79 (1.0% (8 5)). In both age ranges the difference in risk between cigarette smokers and non-smokers was much larger than the difference between one type of cigarette and another (risk ratio 3.39 and 3.95 at ages 30-59 for smokers of similar numbers of low and of medium tar cigarettes, and risk ratio 2.35 and 2.37 at ages 60-79). Most possible confounding factors that could be tested for were similar in low and medium tar users, with no significant differences in blood lipid or albumin concentrations.
Conclusion - The present study indicates that the imminent change of tar yields in the European Union to comply with an upper limit of 12 mg/cigarette will not increase (and may somewhat decrease) the incidence of myocardial infarction, unless they indirectly help perpetuate tobacco use. Even low tar cigarettes still greatly increase rates of myocardial infarction, however, especially among people in their 30s, 40s, and 5Os, and far more risk is avoided by not smoking than by changing from one type of cigarette to another.
ISIS, BHF/ICRF/MRC Clinical Trial Service Unit and Epidemiological Studies Unit Nuffield Department of Clinical Medicine Radcliffe Infirmary Oxford OX2 6HE and Cardiac Department John Radcliffe Hospital Oxford OX3 9DUS Parish senior research fellow R Collins, British Heart Foundation senior research fellow R Peto professor of medical statistics and epidemiology L Youngman senior research fellow J Barton senior administrator K Jayne senior administrator R Clarke research fellow P Appleby research fellow V Lyon research fellow P Sleight professor emeritus of cardiovascular medicine Oxford Bio-Research Laboratory Magdalen Science Park Oxford OX4 4GA S Cederholm-Williams director J Marshall research fellow
Correspondence to: Dr Parish.
Paula Rantakallio, Esa Laara, Markku Koiranen
Abstract
Objective - To investigate long term mortality among women who smoked during pregnancy and those who stopped smoking.
Design - A follow up of a geographically defined cohort from 1966 through to 1993.
Subjects - 11994 women in northern Finland expected to deliver in 1966, comprising 96% of all women giving birth in the area during that year. Smoking habits were recorded during pregnancy but not later.
Main outcome measure - Mortality by cause (571 deaths)
Results - The mortality ratio adjusted for age, place of residence, years of education and marital status was 2-3 (95% confidence interval 1-8 to 2 8) for the women who smoked during pregnancy and 1-6 (1 1 to 2 2) for those who stopped smoking before the second month of pregnancy, both compared with non-smokers. Among the smokers the relative mortality was higher for typical diseases related to tobacco intake, such as respiratory and oesophageal cancer and diseases of the cardiovascular and digestic organs and also for accidents and suicides.
Conclusion - The risk of premature death seems to be higher in women who smoke during pregnancy than in other women who smoke. This may be explained either by the low proportion of those who stop later and the high proportion of heavy smokers or by other characteristics of these subjects that increase the risk.
Department of Public Health Science and General Practice University of Oulu Aapistie 1 FIN-90220 Oulu Finland Paula Rantakallio professor Esa Laara biostatistician Markku Koiranen applications designerCorrespondence to: Dr Rantakallio.
Peter Aaby, Badara Samb, Francois Simondon, Awa Marie Coll Seck, Kim Knudsen, Hilton Whittle
Abstract
Objective - To examine whether the reduction in mortality after standard titre measles immunisation in developing countries can be explained simply by the prevention of acute measles and its long term consequences.
Design - An analysis of all studies comparing mortality of unimmunised children and children immunised with standard titre measles vaccine in developing countries.
Studies - 10 cohort and two case-control studies from Bangladesh, Benin, Burundi, Guinea-Bissau, Haiti, Senegal, and Zaire.
Main outcome measures - Protective efficacy of standard titre measles immunisation against all cause mortality. Extent to which difference in mortality between immunised and unimmunised children could be explained by prevention of measles disease.
Results - Protective efficacy against death after measles immunisation ranged from 30% to 86%. Efficacy was highest in the studies with short follow up and when children were immunised in infancy (range 44-100%). Vaccine efficacy against death was much greater than the proportion of deaths attributed to acute measles disease. In four studies from Guinea-Bissau, Senegal, and Burundi vaccine efficacy against death remained almost unchanged when cases of measles were excluded from the analysis. Diphtheria-tetanus-pertussis and polio vaccinations were not associated with reduction in mortality.
Conclusion - These observations suggest that standard titre measles vaccine may confer a beneficial effect which is unrelated to the specific protection against measles disease.
Epidemiology Research Unit Danish Epidemiology Science Centre Statens Seruminstitut Artillerivej 5 2300 Copenhagen DenmarkCorrespondence to: Dr Aaby.Peter Aaby senior researcher Kim Knudsen senior statistician
ORSTOM Dakar Senegal Badara Samb field physician Francois Simondon project director
University Cheikh Anta Diop Dakar Senegal Awa Marie Coll Seck professor
Medical Research Council Laboratories Banjul Gambia Hilton Whittle deputy director
Ann Crosland, Roger Jones
Abstract
Objectives - To determine prevalence of rectal bleeding in the community and to examine factors that lead some patients to consult their general practitioner about rectal bleeding while others do not.
Design - Questionnaire survey followed by semi-structured interviews of sample of respondents with rectal bleeding.
Setting - Two general practices on Tyneside.
Subjects - 2,000 adult patients registered with the general practices were sent a validated questionnaire. Respondents with rectal bleeding were divided into consulters and non-consulters, and 30 patients from each group (matched for age, sex, and characteristics of bleeding) were interviewed.
Main outcome measures - Prevalence of rectal bleeding, proportion of subjects with rectal bleeding who sought medical advice, and reasons for consulting or not consulting a doctor about rectal bleeding.
Results - 287 of the 1200 respondents to the questionnaire had noticed rectal bleeding at some time in their lives, and 231 had noticed it within previous 12 months. Only 118 (41%) of all respondents with rectal bleeding had ever sought medical advice for the problem. Those aged over 60 were most likely to have consulted, as were those who reported blood mixed with their stools. Main difference between those who had sought medical advice and those who had not was that consulters were more likely than non-consulters to perceive their symptoms as serious.
Conclusions - Although rectal bleeding is common, only minority of patients seek medical advice for their bleeding. Perception of seriousness of symptoms seems to be most important factor in deciding whether to consult a doctor for rectal bleeding.
Department of Primary Health Care University of Newcastle upon Tyne Newcastle upon Tyne NE2 4HH Ann Crosland research associateCorrespondence to: Dr Crosland.Department of General Practice United Medical and Dental Schools of Guy's and St Thomas's Hospitals London SE11 6SP Roger Jones Wolfson professor