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The results of a previous study of the use of oral contraceptives by married women discharged from hospital with a diagnosis of thromboembolic disease in the years 1964-6 were reported by us last year. The present paper adds results relating to patients discharged during 1967 and a few data, that could not be sought previously, for patients discharged with cerebral or coronary thrombosis from three of the hospitals in the earlier period.Of 84 patients with deep-vein thrombosis or pulmonary embolism 42 (50%) had used oral contraceptives during the month preceding the onset of their illness, while only 23 of the 168 controls (14%) had done so. No differences in risk were found either for the types of preparation or for the duration of use. After allowance for age and height, the patients with venous thromboembolism were about 10 lb. (4,535 g.) heavier than the control patients, irrespective of whether they were using oral contraceptives or not. No appreciable difference was found between the smoking habits of patients with and without venous thromboembolism treated during 1967, nor between women who were using oral contraceptives and those who were not. The trend in hospital admissions for venous thromboembolism with time corresponded to the trend in the use of oral contraceptives, and there was no evidence to suggest that the number of admissions was affected by publicity about the risk of using the preparations. Of 19 patients with cerebral thrombosis 11 (58%) had been using oral contraceptives, compared with an expected figure of 3.5 from the experience of the control subjects. All the published data (clinical, angiographic, and post-mortem) show that the thrombosis affects the cerebral arteries rather than the cerebral veins. Of 17 patients with coronary thrombosis 2 (12%) had been using oral contraceptives, compared with an expected figure of 2.1. The patients with coronary thrombosis smoked more than the control patients and were, on average, 8.3 lb. (3,765 g.) heavier than control women of the same age and height.The new evidence strengthens the belief that oral contraceptives are a cause of venous thromboembolism and cerebral thrombosis but does not indicate that they are a cause of coronary thrombosis.

The incidence of idiopathic deep vein thrombosis and pulmonary embolism in a group of nurses (9·4 per 1,000 per year and 7·5 per 1,000 per year respectively) was much higher than the reported incidence in women of childbearing age in the general population (0·65 per 1,000 per year and 0·11 per 1,000 per year respectively). We suggest that these results show that nurses face an increased risk of idiopathic thromboembolism as a result of their occupation.

Three experiments on smokers have been performed to determine variations in blood levels of carboxyhaemoglobin (COHb) throughout the day and night and whether a random measurement of COHb gives a true estimation of a smoker's mean COHb level. In the individual smoker the COHb level does not increase gradually during the day but is kept within relatively narrow limits. Moderately heavy smokers rise in the morning with a substantially raised COHb level because the half life of COHb is significantly longer during sleep than during the day. Women excrete their carbon monoxide faster than men. A random COHb estimation gives a good indication of the mean COHb level of an individual.

Male volunteers for mass radiography examination aged 40 or more were questioned about their sputum production, smoking habits, and, when applicable, their method of smoking cigarettes.Of 5,438 cigarette smokers 1,051 (19%) claimed that when smoking a cigarette they usually extinguished it at some stage and later relit it to smoke again. Anyone who admitted to producing sputum from his chest on most days of the year or on most days for a minimum of three months of the year for at least the last two years was classed, in the absence of other causative disease, as a chronic bronchitic. Such chronic bronchitics totalled 1,864 (34%).The rate of chronic bronchitis among relighters (39.7%) was higher than the rate (32.9%) among the remaining cigarette smokers. The difference was of high statistical significance (P

The reproductive performance of sisters and sisters-in-law of 185 women who had delivered “light-for-dates” and “premature expulsion” low birth weight infants was studied. Percentile birth weights were compared taking into account length of gestation, fetal sex, and the height, weight, parity, and smoking habits of the mother. Sisters of women who had delivered light-for-dates babies had lighter babies than the general population, their sisters-in-law, or the sisters of women in the premature expulsion group. These other groups, however, had the expected distribution of percentile birth weights. Data on familial trends in smoking habits and unknown gestation are also presented. The results are consistent with the theory that the mother9s own intrauterine experience affects her reproductive performance but could also be explained by shared family learning experience of as yet unidentified microsocial factors related to pregnancy performance.

During 1965-9 22 women aged 41 years or less have been seen with myocardial infarction. Eleven had been taking oral contraceptives. This prevalence of oral contraception (50%) is appreciably greater than that estimated for women of the same age in the general population.Nine of these 11 women had an independent increased risk of developing ischaemic heart disease because of hyperlipidaemia, hypertension, or excessive cigarette smoking. Ten of the 11 not taking an oral contraceptive also had a readily identifiable predisposing factor. None of the 22 showed carbohydrate intolerance. The similarity of the two groups is the striking finding. Details of 15 women of comparable age seen during 1960-4 before oral contraceptives were widely used are also presented, and they had similar characteristics.Oral contraceptives do not appear on their own to increase the risk of developing myocardial infarction, but they may do so in women otherwise prone to ischaemic heart disease. Suggestions are made for the identification of these women.

Data are presented on the incidence of ischaemic (coronary) heart disease and duodenal ulcer among the several thousand male medical practitioners aged 35–64 holding immediate sickness benefit policies with the Medical Sickness Annuity and Life Assurance Society Limited. Three periods are considered: 1947–50, 1957–60, and 1961–5. The incidence of first clinical episodes of ischaemic heart disease in the doctors altered little between 1947–50 and 1957–60 but increased in 1961–5. Comparison of the late 1940s with the early 1960s shows a 60% rise of incidence at ages 45–54 but little change at other ages. Cases first presenting as “sudden” death increased between 1947–50 and 1961–5 by 111% at 45–54, and again changed little at 55–64. In two other occupational groups that have been studied—bus conductors and insurance salesmen—the increase of incidence was greater than for the doctors at 45–54 and it occurred also over 55 years of age. The increase from 1947–50 to 1961–5 in mortality during all episodes of ischaemic heart disease was the same in the doctors as in the male population of England and Wales at 45–54, but at 55–64 it was less. The results in the doctors are not due to alterations over the period in length of sickness absence, or underwriting policy, or of the nomenclature used on the certificates. Well-documented changes in the smoking habits of doctors may be partly responsible for what appears to have been a relatively favourable experience of ischaemic heart disease from 1947–50 to 1961–5, especially at ages 55–64. Incidence of duodenal ulcer at ages 35–64 declined steadily in this population of doctors from 1947–50 to 1961–5. The decline is very likely to be real.

The change in specific airway conductance produced by smoking a cigarette under standard conditions was measured in 91 heavy smokers. Subsequently 19 of the most reactive subjects smoked two cigarettes with different filters and another containing cigar tobacco. The results indicated that reactivity to cigarette smoke was reduced significantly by increasing the retention efficiency of the filter and that reactivity to inhaled cigar-tobacco smoke was no less than that to cigarette smoke.

Only 20 patients with optic neuritis of unknown aetiology could be collected in Bombay over a period of two and a half years. Only six of them were smokers and only three (one a non-smoker) had bilateral centrocaecal scotomata similar to those found in tobacco amblyopia. In 11 untreated patients the serum vitamin B(12) and plasma thiocyanate levels were estimated and found to show no significant differences from those in normal control subjects. Treatment with hydroxocobalamin in the majority of cases and with cyanocobalamin, corticotrophin, or prednisolone in the rest showed equally good results; spontaneous improvement was seen in one case.No significant role could be assigned to smoking (cyanide) or to vegetarianism in the production of optic neuritis in these patients; nor was there any evidence of depletion of total (cyanide-extracted) B(12) or of an increase in the proportion of non-cyanide-extracted B(12) in the serum.

In a retrospective study of the incidence of mesothelioma in Scotland for 1950-67 80 cases were traced from pathological reports and biopsy material of malignant tumours invading the pleura and peritoneum. These cases were matched with two sets of controls. Detailed histories of residence, occupation, and degree of exposure to asbestos confirmed that the incidence of mesothelioma in Scotland is similar to that in other parts of Britain.

During 1965-9 22 women aged 41 years or less have been seen with myocardial infarction. Eleven had been taking oral contraceptives. This prevalence of oral contraception (50%) is appreciably greater than that estimated for women of the same age in the general population.Nine of these 11 women had an independent increased risk of developing ischaemic heart disease because of hyperlipidaemia, hypertension, or excessive cigarette smoking. Ten of the 11 not taking an oral contraceptive also had a readily identifiable predisposing factor. None of the 22 showed carbohydrate intolerance. The similarity of the two groups is the striking finding. Details of 15 women of comparable age seen during 1960-4 before oral contraceptives were widely used are also presented, and they had similar characteristics.Oral contraceptives do not appear on their own to increase the risk of developing myocardial infarction, but they may do so in women otherwise prone to ischaemic heart disease. Suggestions are made for the identification of these women.

The ventilatory capacity, including flow-volume curves of 313 men, all 50 years old, was examined in 1963 and 1967. The group as a whole, which included persons with chronic bronchitis, with “other respiratory symptoms,” and without respiratory symptoms, showed the same absolute decrease in ventilatory capacity. Vital capacity, forced expiratory volume, and maximum expiratory flow all dropped more for the smokers than for either the non-smokers or the ex-smokers. In those who had stopped smoking for four years or less, however, ventilatory capacity did not decline significantly less than in those who continued to smoke.

The smoking behaviour of 36 subjects smoking cigarettes with different filter retention efficiencies for nicotine was studied. Subjects were observed while performing various tasks on a driving simulator and also during a resting period after the tasks. Smokers of cigarettes with high-retention filters took more frequent puffs and obtained nearly the same amount of nicotine as smokers of cigarettes with low-retention filters, both while performing the tasks and during the resting period. Smokers of both types of cigarettes took significantly more puffs and obtained more nicotine per unit time during the resting period than during the tasks. The results are compatible with the possibility that smokers automatically adjust the nicotine dose obtained from a cigarette to some “optimum” level which may vary with different activities.

A study of the relation between smoking habits and lung cancer in male industrial workers over a period of three years has confirmed the earlier findings in doctors that the death-rate from lung cancer correlates closely with the number of cigarettes smoked. Of 54,460 men studied 68.7% were current cigarette smokers. The annual mortality rate from lung cancer was 0.33 per thousand in non-smokers and ex-smokers, and 1.2 per thousand for all cigarette smokers, and higher in heavy smokers.Heavy cigarette smokers who retained the cigarette in the mouth between puffs ("drooping" cigarette habit) had an annual mortality rate of 4.1 per thousand.The mortality from coronary thrombosis in smokers was nearly three times that in non-smokers. A mortality gradient with rising consumption of cigarettes was observed.Some correlation between smoking and cancer of other sites and from non-neoplastic lung disease was observed in older men, but no correlation was found with other cardiovascular diseases and cerebrovascular diseases.