Smoking behavior among participants in the nurses' health study.

We analyzed smoking behavior of 91,651 married female nurses, aged 30-55 years in 1976. The prevalence of smoking was similar among all birth cohorts. The largest percentage increase in starting to smoke occurred between ages 15 and 25 years; by age 25, 50 per cent had started smoking. The cessation rate was lowest in earlier birth cohorts and among nurses starting to smoke at earlier ages. The cessation rate increased substantially between 1963-73 compared with the period 1948-58.     

Prospective study of short stature and newly diagnosed asthma in women.

The authors tested the hypothesis that short stature predicts adult-onset asthma independent of obesity among women in the Nurses' Health Study. Height, weight, and physician-diagnosed asthma were assessed with validated questionnaire items. Proportional hazard models adjusted separately for weight and body mass index. The rate of newly diagnosed asthma was 1.55 times greater in the shortest versus the tallest quintile after adjustment for weight (95% CI, 1.26-1.91). After adjustment for body mass index, the rate ratio was 1.16 (95% CI, 0.94-1.42). Short stature predicted adult-onset asthma in a large cohort of women, but this association was not independent of obesity.     

Prospective study of relative weight, height, and risk of breast cancer

We examined relative weight and height in relation to subsequent breast cancer risk among 115,534 women 30 to 55 years of age and free from cancer in 1976. By 1984, six hundred fifty-eight premenopausal and 420 postmenopausal breast cancers were documented during 734,716 person-years. Among premenopausal women, risk of breast cancer decreased significantly with increasing relative weight (relative risk for the highest category was 0.6). A similar inverse association was seen for recalled relative weight at 18 years of age. Postmenopausal breast cancer was not associated with relative weight, either recent or at age 18. Height was not associated with breast cancer risk among premenopausal women and only weakly related among postmenopausal women. These data suggest that obesity among premenopausal and early postmenopausal women does not increase breast cancer risk substantially.     

Reproducibility and validity of self-reported menopausal status in a prospective cohort study

The reproducibility and validity of self-reported menopausal status were evaluated among the 121,700 female US registered nurses aged 30-55 years in 1976 who are participants in the Nurses' Health Study, a prospective cohort study of diseases in women. When questioned in 1978, 6,591 of the women who were premenopausal in 1976 reported that their menses had ceased and provided their age at menopause. Two years later, in 1980, 98.8 per cent of the 6,591 women again reported that they were postmenopausal and again gave the reasons for menopause (natural or surgical). Among those women who reported surgical menopause during the 1976-1978 follow-up interval, age at menopause was reported to within one year on both the 1978 and 1980 questionnaires by 95 per cent of women. Among those reporting natural menopause during the 1976-1978 period, 82 per cent of women reported their age at menopause to within one year on the two follow-up questionnaires. A random sample of 255 women reporting surgical menopause between 1982 and 1984 was identified and medical records were obtained for 200. For all but two women, there was complete agreement between self-report and medical record for details of hysterectomy and extent of ovarian surgery. The reproducibility of self-reported age at menopause was assessed among 31,405 women who were menopausal in 1976. Reported age at menopause on consecutive questionnaires showed increasing within-person variance with increasing duration since menopause.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of genetic and nongenetic influences on pulmonary function. A twin study

To better understand the extent to which familial similarities in pulmonary function (PF) are attributable to genetic rather than to shared environmental influences, we studied the twinship aggregation of PF in 256 monozygotic (MZ) and 158 dizygotic (DZ) adult twin members of the Greater Boston Twin Registry. Genetic influences on various spirometric measures were estimated with twinship intrapair correlations adjusted using a regression model to control for similarities in the anthropomorphic characteristics of twins, and for the effects of a number of environmental factors that included childhood respiratory illness, occupational dust exposure, and smoking history. A significant influence of smoking on all air-flow measures was observed in this population for whom genetic similarities were adjusted. However, highly significant adjusted intrapair correlations for all spirometric measures, ranging from 0.52 to 0.76, were observed for the MZ twins. The intrapair correlations for the DZ twins were approximately one-half the magnitude of those for the MZ twins. These data suggest that a large proportion of the measured variability in PF may be accounted for by genetic influences other than those associated with body size.     

Prospective study of estrogen replacement therapy and risk of breast cancer in postmenopausal women

We prospectively examined the use of estrogen replacement therapy in relation to breast cancer incidence in a cohort of women 30 to 55 years of age in 1976. During 367 187 person-years of follow-up among postmenopausal women, 722 incident cases of breast cancer were documented. Overall, past users of replacement estrogen were not at increased risk (relative risk, 0.98; 95% confidence interval, 0.81 to 1.18), including even those with more than 10 years since last [corrected] use (relative risk after adjustment for established risk factors, 0.70; 95% confidence interval, 0.45 to 1.10). However, the risk of breast cancer was significantly elevated among current users (relative risk, 1.36; 95% confidence interval, 1.11 to 1.67). Among current users, a stronger relationship was observed with increasing age but not with increasing duration of use. These data suggest that long-term past use of estrogen replacement therapy is not related to risk of breast cancer but that current use may modestly increase risk.     

Respiratory symptoms and lung function in relation to passive smoking: a comparative study of American and French women

Results are reported from a parallel analysis of the association of passive smoking with respiratory symptoms and lung function (FEV1, FVC and FEV1/FVC) in 2220 US and 3855 French women from the general population examined over the same time period using similar methods. Age, city, educational level, occupational exposure and height (for lung function) were taken into account. In the US survey, being a never smoker married to a current or former smoker was significantly associated only with wheezing compared to being a true never smoker. A borderline significant association between passive smoking and dyspnoea was observed among women older than 40 in the French survey. No association was observed with cough or phlegm production. Passive smoking was significantly related to lower FVC and FEV1 values among French women 40 years or more, even among those without a history of wheeze or asthma. However, even among US women older than 40 years of age, there was no significant association between passive smoking and level of lung function. Better housing conditions, higher divorce rates, more frequent exposure to passive smoking in childhood, and different selection factors for active smoking in the US compared to France might explain the lack of association of current spousal smoking habits with lower lung function in American women.     

Longitudinal study of the effects of maternal smoking on pulmonary function in children

We investigated the effects of maternal cigarette smoking on pulmonary function in a cohort of children and adolescents observed prospectively for seven years. A multivariate analysis revealed that after correction for previous forced expiratory volume in one second (FEV1), age, height, change in height, and cigarette smoking in the child, or adolescent, maternal cigarette smoking significantly lowered the expected average annual increase in FEV1 (P = 0.015). On the basis of this analysis, it is estimated that if two children have the same initial FEV1, age, height, increase in height, and personal cigarette-smoking history, but the mother of one has smoked throughout the child's life whereas the mother of the other has not, the difference in the change in FEV1 over time in the exposed child, as compared with that in the unexposed child, will be approximately 28, 51, and 101 ml after one, two, and five years, respectively, or a reduction of 10.7, 9.5, and 7.0 per cent, respectively, in the expected increase. These results suggest that passive exposure to maternal cigarette smoke may have important effects on the development of pulmonary function in children.     

A prospective study of past use of oral contraceptive agents and risk of cardiovascular diseases

We evaluated the effects of past use of oral contraceptive agents on the risk of various cardiovascular diseases among women in the Nurses' Health Study cohort. We studied 119,061 women who were 30 to 55 years of age in 1976, who provided information on their use of oral contraceptives, and who at entry had had no previous coronary disease or stroke. End points were documented by medical records. During eight years of follow-up (484,096 person-years among those who had never used oral contraceptives, 415,488 among past users, and 22,376 among current users), there were 485 new cases of major coronary disease (380 nonfatal myocardial infarctions and 105 deaths from coronary disease), 282 strokes (205 nonfatal and 77 fatal), and 48 other deaths from cardiovascular causes. We found no evidence to suggest an increase in the risk of cardiovascular diseases among past users of oral contraceptives, even with prolonged previous use. After adjustment for a variety of risk factors, the relative risk of major coronary disease for women who had used oral contraceptives in the past, as compared with those who had never used such agents, was 0.8 (95 percent confidence interval, 0.6 to 1.0); of stroke, 1.0 (95 percent confidence interval, 0.7 to 1.3); and of death from all cardiovascular causes, 0.9 (95 percent confidence interval, 0.7 to 1.2). We found neither evidence of increased risk with longer use nor any trend with the amount of time since the last use. According to these prospective data, the use of oral contraceptive agents in the past does not materially raise a woman's risk of subsequent cardiovascular disease.