Symptom-limited graded treadmill exercise testing in young adults in the CARDIA study

Symptom-limited, graded exercise treadmill testing was performed by 4,968 white and black adults, ages 18-30 yr, during the baseline examination for the CARDIA study. The mean estimated maximal exercise capacity by race/gender, expressed as metabolic units (METS), was: white men 13.8, black men 13.0, white women 11.1, and black women 9.4. Exercise test duration was higher in nonsmokers, positively related to physical activity score and pulmonary function (FEV1.ht-2), and inversely related to body mass index. Men had higher mean values than women for both test duration and a measure of submaximal performance, the workload 130 (WL130, the exercise test duration to a heart rate of 130 beats.min-1). Adjusted for age and education, white men had a longer mean test duration than black men (53 s longer, P less than 0.001), but nearly equal mean WL130. White women had higher mean values than black women for both test duration (114 s longer, P less than 0.001) and WL130 (36 s longer, P less than 0.001). Men had higher mean values than women for both outcome measures (P less than 0.001). Thus, in young adults significant gender and ethnic differences exist for exercise test performance, part of which can be explained by personal habits or traits.

Incidence of surgically treated benign prostatic hypertrophy and of prostate cancer among blacks and whites in a prepaid health care plan

The incidence of surgically treated benign prostatic hypertrophy and of prostate cancer was examined to December 1987 in 14,897 men (2,175 blacks and 12,722 whites) who received multiphasic health checkups during 1971-1972 while members of the Kaiser Permanente Medical Care Program (San Francisco-Oakland, California). Prostate cancer incidence was higher in blacks than in whites for all age groups (age-adjusted relative risk (RR) = 1.8, 95% confidence interval (CI) 1.4-2.3). The incidence of benign prostatic hypertrophy was somewhat higher in blacks than in whites until age 65 years, after which it was higher in whites. In contrast to the risk of prostate cancer, the age-adjusted risk of benign prostatic hypertrophy was the same for blacks as for whites (RR = 1.0, 95% Cl 0.8-1.2).

A multivariate analysis of risk factors for preeclampsia

OBJECTIVE

--To determine, in a multivariate analysis, risk factors for preeclampsia that could be observed early in pregnancy and to establish whether these risk factors are different for nulliparas and multiparas.

DESIGN

--A case-control study of preeclampsia.

SETTING

--Women who gave birth at Northern California Kaiser Permanente Medical Centers in 1984 and 1985.

PARTICIPANTS

--Preeclamptic cases (n = 139) were determined from discharge diagnosis of severe preeclampsia and by confirmation of blood pressures and proteinuria from medical records. Controls (n = 132) were randomly selected women who had no discharge diagnosis of any hypertensive disorder of pregnancy and who had no evidence of hypertension or proteinuria from medical record review.

MAIN VARIABLES EXAMINED

--Medical records were abstracted for information regarding maternal age, race, previous pregnancy history, family medical history, socioeconomic status, employment during pregnancy, body mass, and smoking and alcohol consumption.

RESULTS

--Multiple logistic regression analyses confirmed that case patients were more likely than control patients to be nulliparous (adjusted odds ratio [OR], 5.4; 95% confidence interval [Cl], 2.8 to 10.3) and that preeclampsia in a previous pregnancy greatly increased the risk in a subsequent one (adjusted OR, 10.8; 95% Cl, 1.2 to 29.1). However, regardless of parity, preeclamptic women were also more likely to be of high body mass (adjusted OR, 1.7; 95% Cl, 1.2 to 6.2), to work during pregnancy (adjusted OR, 2.1; 95% Cl, 1.1 to 4.4), and to have a family history of hypertension (adjusted OR, 1.7; 95% Cl, 0.92 to 3.2). Having a previous history of a spontaneous abortion was protective but only in multiparous women (adjusted OR for multiparas, 0.09; 95% Cl, 0.02 to 0.48). In contrast, being black was a significant risk for preeclampsia but only in nulliparous women (adjusted OR for nulliparas, 12.3; 95% Cl, 1.6 to 100.8).

CONCLUSIONS

--There are a number of risk factors for preeclampsia that may be determined early in a woman's pregnancy. Multiparas and nulliparas share certain risk factors but not others. A cohort investigation is needed to determine the ability of these risk factors to predict who develops preeclampsia.

Risk factors for surgically treated benign prostatic hyperplasia in a prepaid health care plan

The relationship of age, medical history, personal habits, and urologic symptoms to the incidence of surgically treated benign prostatic hyperplasia (BPH) was studied in a cohort of 16,219 men, aged forty years and over, who received multiphasic health checkups (MHCs) during 1971 and 1972 in Oakland or San Francisco while members of the Northern California Kaiser Permanente Medical Care Program, a large prepaid health care program. Follow-up was carried out for surgically treated BPH from the date of the MHC to the date of the earliest of the following: surgery for BPH (n = 1,027); incidence of prostate cancer (n = 329), bladder cancer (n = 119), or both (n = 10); other prostate surgery (n = 5); death (n = 2,525); membership termination (n = 4,235); or December 31, 1987 (n = 7,969). The mean length of follow-up was twelve years. In multivariate analysis utilizing the Cox proportional hazards model, the following characteristics were positively associated (p less than 0.05) with risk of surgically treated BPH: age, low body mass index, nonsmoking (vs. current smoking), urine pH greater than 5, history of kidney x-ray and of tuberculosis, and each of five urologic symptoms (dysuria, loss of bladder control, trouble starting urination, nocturia, slow urine stream). The risk of BPH associated with obstructive urologic symptoms decreased markedly with age. Some of these findings are consistent with those from other studies (age, nonsmoking), while others (high urine pH, history of tuberculosis) are new and should be examined in other study populations.

Comparison of two methods of assessing physical activity in the Coronary Artery Risk Development in Young Adults (CARDIA) Study

Physical activity was assessed by questionnaire among 4,956 young blacks and whites aged 18-30 years at the baseline examination (1985-1986) of the Coronary Artery Risk Development in Young Adults (CARDIA) study, a longitudinal study of cardiovascular risk factors. The Physical Activity Recall questionnaire categorized all activity during the previous week, while the Physical Activity History questionnaire quantified participation in 13 specific activities during the previous year. This report compares the two questionnaires with regard to their characterization of the activity levels of the sociodemographic subgroups of the study population and their associations with known physiologic correlates of physical activity. Both questionnaires resulted in the same physical activity patterns for sex (men greater than women) and age (younger greater than older) strata. However, the mean Physical Activity History score was higher in white women than in black women, while the Physical Activity Recall scores were nearly equal. The Physical Activity History score was directly related to educational status, and the Physical Activity Recall score was inversely related to educational status. The Physical Activity History score was generally more strongly associated with physiologic variables known to be related to physical activity (e.g., treadmill test duration). Based upon these findings, which may only be appropriate in this age group, it was concluded that the Physical Activity History score was the more valid measure of habitual physical activity in this study group of young adults.

Alcohol drinking and cigarette smoking: an exploration of the association in middle-aged men and women

The association of alcohol and cigarette consumption was explored among 13,673 black or white persons aged 40-49 years, who received check-ups from mid-1979 to 1985. Alcohol use was strongly associated with number of cigarettes smoked per day, but not with tar-yield, mentholation and presence of filters. Duration of cigarette use, frequency and depth of inhalation, proportion of cigarette smoked and greater time from arising to first cigarette were significantly related to alcohol use in some but not all race-sex groups. Among smokers who consumed alcohol, liquor drinkers smoked the most cigarettes per day and wine drinkers the least. Thus, the association between alcohol drinking and cigarette smoking is strong in middle-aged persons but there are race- and sex-related disparities when specific aspects of smoking behaviour are considered.

Vasectomy and the risk of prostate cancer in a cohort of multiphasic health-checkup examinees: second report

The relationship of vasectomy to prostate cancer was studied in 5,119 men men with a self-reported history of vasectomy, identified at multiphasic health checkups undergone during 1977-82 while members of the Northern California Kaiser Permanente Medical Care Program. Three unvasectomized comparison subjects were identified for each vasectomized man, matched for age, race, marital status, and date and location of the examination. Follow-up for incident prostate cancer was conducted for a mean length of 6.8 years. The relative risk of prostate cancer associated with vasectomy was 1.0 (95% confidence interval = 0.7 - 1.6); the relative risk was approximately one, regardless of length of interval (less than 10 years, 10-20 years, more than 20 years) between vasectomy and multiphasic health checkup or the age at vasectomy (less than 40 years vs more than 40 years). These data support earlier findings reported in this study group of the lack of an association of vasectomy with subsequent risk of prostate cancer.

Correlates of fasting insulin levels in young adults: the CARDIA study

Elevated fasting insulin is an independent risk factor for hyperlipidemia, hypertension, and cardiovascular disease, but determinants of insulin other than age and body mass remain poorly described. Potentially modifiable factors associated with insulin were identified by correlating anthropometric, dietary and physical activity data in the CARDIA cohort of 2643 black and 2472 white men and women aged 18-30 years. Insulin was positively correlated with serum glucose, body mass index (BMI), skinfold thickness, waist/hip ratio and sucrose intake, and negatively correlated with heavy physical activity score, treadmill exercise duration, and magnesium intake (each p less than 0.01). After adjustment for other covariates, the positive association of insulin with waist/hip ratio, skinfold thickness, and sucrose intake remained in the group as a whole, as did the negative associations with magnesium and treadmill duration. These relationships provide insight into potentially modifiable factors affecting insulin levels, and should be considered in interpreting associations between insulin levels and cardiovascular disease.

High blood cholesterol in elderly men and the excess risk for coronary heart disease

OBJECTIVE

To determine whether high blood cholesterol is an important risk factor for mortality from coronary heart disease in elderly men.

DESIGN

Cohort study with a mean follow-up of 10.1 years.

SETTING

A health maintenance organization.

PATIENTS

The cohort included 2746 white men 60 to 79 years of age who had no self-reported history of coronary heart disease.

MEASUREMENT AND MAIN RESULTS

A total of 260 deaths occurred during 27,842 person-years of follow-up. The relative risk for mortality from coronary heart disease in men 60 to 79 years of age in the highest serum cholesterol quartile was 1.5 (95% CI, 1.2 to 2.0) compared with those in the three lower quartiles combined. The relative risk did not change greatly with age, ranging from 1.4 in men 60 to 64 years of age to 1.7 in men 75 to 79 years of age. However, because mortality from coronary heart disease increased with age, the excess risk for such mortality attributable to elevated serum cholesterol levels increased fivefold over these 20 years, from 2.2 deaths per 1000 person-years to 11.3 deaths per 1000 person-years.

CONCLUSIONS

Our results support those of other observational studies in elderly men. If treatment of high blood cholesterol is as effective in reducing cholesterol-related risk for coronary heart disease after 65 years of age as it is in middle-aged men, it might actually produce greater reductions in mortality due to coronary heart disease. A clinical trial is needed to confirm this extrapolation.

The leucocyte count: correlates and relationship to coronary risk factors: the CARDIA study

Correlates of the leucocyte count (WBC) and its relationships to other coronary heart disease (CHD) risk factors were assessed in 4981 black and white young adults. Mean WBC was higher in women than men, higher in whites than blacks, and higher in those aged 18-24 than aged 25-30 years. It also varied by season with the highest levels in the autumn. Other characteristics with persistent statistically significant direct associations with the WBC after multivariate adjustments were cigarette smoking, marijuana use, geographical location (possibly an inter-laboratory artifact), use of birth control pills, body mass index, pulse rate, and systolic blood pressure; height, physical fitness and high density lipoprotein cholesterol (HDL-C) level were inversely associated with the WBC. The negative association of WBC with HDL-C was too small to explain the association of WBC with CHD found elsewhere. The WBC is a commonly performed clinical test; yet much remains to be learned about its variation in the general population and its value as a predictor rather than merely an indicator of disease.

Racial differences in serum cotinine levels among smokers in the Coronary Artery Risk Development in (Young) Adults study

Cotinine was measured in the serum of nearly all 5,115 18-30 year old, Black and White, men and women participating in the Coronary Artery Risk Development in (Young) Adults Study, 30 percent of whom reported current cigarette smoking. Ninety-five percent of the reported smokers had serum cotinine levels indicative of smoking (greater than 13 ng/ml). The median cotinine level was higher in Black than White smokers (221 ng/ml versus 170 ng/ml; 95 percent CI for difference: 34, 65) in spite of the fact that estimated daily nicotine exposure and serum thiocyanate were higher in Whites. The difference persisted after controlling for number of cigarettes, nicotine content, frequency of inhalation, weekly sidestream smoke exposure, age, gender, and education. A reporting bias and nicotine intake were ruled out as explanations for the racial difference suggesting that the metabolism of nicotine or the excretion of cotinine may differ by race. Racial differences in cotinine levels may provide clues to the reasons for the observed lower cessation rates and higher rates of some smoking-related cancers in Blacks.

Evidence of discrepant data regarding trends in marijuana use and supply, 1985-1988

Between 1985 and 1988, the estimated number of current marijuana users (i.e., use within the past 30 days) in the United States declined 36%, based on self-report data from the National Household Survey on Drug Abuse. During the same time period, estimated nondomestic production of marijuana available for consumption in the United States increased 58% and domestic production increased 119%, while there was no clear-cut trend in prices. Reports of marijuana use associated with emergency room visits more than doubled in these years. The reasons for these apparent discrepancies in the data regarding the supply and use of marijuana are unknown. The possible causes of change in these and other measures of illicit drug use are examined because they form the basis for assessment of the efficacy of the recently proposed 1989 National Drug Control Strategy.

Obesity and overweight in young adults: the CARDIA study

The associations of body size with age, race, sex, and education in young adults were examined in 5,115 black and white, men and women ages 18-30 years. Black women were more obese than white women with greater mean levels of body mass index (25.8 vs 23.1 kg/m2), subscapular skinfold thickness (19.9 vs 15.2 mm), and waist girth (76.7 vs 72.0 cm), all P less than 0.0001. Black women were more likely to exceed 20% of ideal body weights (black women 23.7%, white women 9.1%, P less than 0.0001). No similar differences were found in men. Associations of measures of body size with age and education differed among race/sex groups. Body mass index and skinfolds increased with age among white and black men and black women, but not among white women. The association of education with obesity was negative among white women and positive among black men with no significant association noted among white men and black women. These data show a complex relationship between age, sex, race, education, and obesity in young adulthood.

Association of fasting insulin with blood pressure and lipids in young adults. The CARDIA study

The association of insulin with cardiovascular disease (CVD) may be mediated in part by the associations of insulin with CVD risk factors, particularly blood pressure and serum lipids. These associations were examined in 4576 black and white young adults in the CARDIA Study. Fasting insulin level was correlated in univariate analysis with systolic blood pressure (r = 0.16), diastolic blood pressure (r = 0.13), triglycerides (r = 0.27), total cholesterol (r = 0.10), high density lipoprotein (HDL) cholesterol (r = -0.25), and low density lipoprotein (LDL) cholesterol (r = 0.14), and with age, sex, race, glucose, body mass index, alcohol intake, cigarette use, physical activity, and treadmill duration (all p less than 0.0001). After adjustment for these covariates, insulin remained positively associated with blood pressure, triglycerides, total and LDL cholesterol, and apolipoprotein B and was negatively associated with HDL, HDL2 and HDL3 cholesterol, and apolipoprotein A-I in all four race-sex groups. Higher levels of fasting insulin are associated with unfavorable levels of CVD risk factors in young adults; these associations, though relatively small, can be expected to increase the risk of atherosclerosis. Demonstration of these relationships in a large, racially diverse, healthy population suggests that insulin may be an important intermediate risk factor for CVD in a broad segment of the U.S. population.

Cigarette smoking behavior is strongly related to educational status: the CARDIA study

The prevalence and correlates of cigarette smoking were examined in 5,116 men and women ages 18-30 years including both blacks and whites of varied educational levels. Prevalence of smoking was approximately 30% in each race by gender subgroup after adjusting for age and education. The prevalence decreased with increasing education, from 54% among participants with less than a high school education to 12% among those with graduate degrees (P less than 0.001). Cessation rates followed a similar pattern, with former smokers twice as common among those with more education. Differences in smoking prevalence across occupational groups were largely explained by differences in educational achievement. More educated individuals smoked fewer cigarettes per day and chose brands with lower nicotine yield. Race and gender were not strongly related to smoking prevalence. However, among smokers, whites reported smoking 50% more cigarettes per day than blacks but the average nicotine and tar content of the cigarette was nearly three times higher among blacks than whites. The strong inverse relationship between education and cigarette smoking patterns has important implications for public health efforts directed at the prevention of cigarette smoking.

Body mass index and 15-year mortality in a cohort of black men and women

The association between body mass index (BMI) and mortality was investigated in 2453 black male (aged 30-79 years) and 2731 black female (aged 40-79 years) members of the Kaiser Foundation Health Plan. During a 15-year follow-up 393 male and 283 female deaths were identified. Analyses were conducted separately in a lower and an upper range of BMI (as well as over the entire range), to isolate separate effects of low weight and high weight on mortality. Particular attention was also paid to potential bias from cigarette smoking and antecedent illness. Cox regression analyses showed that over the entire range of BMI the adjusted BMI-mortality association was significantly J-shaped for the men and essentially flat for the women. The inverse association between BMI and mortality in the lower range of BMI was statistically significant for the men; the adjusted relative hazard increasing from the 10th to the 50th percentile of BMI was 0.76 (95% confidence interval [CI] 0.59-0.98). The positive association between BMI and mortality in the upper range of BMI was highly statistically significant for the men; the adjusted relative hazard increasing from the 50th to the 90th percentile of BMI was 1.37 (95% CI 1.14-1.63). Whether controlled by multivariate analysis, by excluding the first 5 years of follow-up from the analyses, or by analyzing the BMI-mortality association in smoking-specific and/or illness-specific subgroups, smoking and antecedent illness did not have much impact on the BMI-mortality association, in either sex. The general observations on the BMI-mortality association are similar to findings in some white cohorts.

Mentholated cigarette use among multiphasic examinees, 1979-86

Mentholated cigarette use was studied in relation to age and race in 29,037 current smokers who were Kaiser Permanente Medical Care Program members. The percentages of mentholated cigarette users were much higher in Blacks and Asians than in Whites, especially in the younger age groups. A marked inverse relationship between mentholated cigarette use and age was present in Blacks and Asians; mentholated cigarette use showed little difference with age in Whites.

Hip fracture in women. Incidence, in-hospital mortality, and five-year survival probabilities in members of a prepaid health plan

The problem of hip fracture is especially serious for women, who live longer than men and who have a higher risk of the condition. Data on women older than 49 years enrolled in a prepaid medical care program were analyzed to determine the incidence of hospitalization for hip fracture, in-hospital death rate, and five-year probability of survival after hip fracture. The cumulative lifetime probability of hip fracture for women alive at age 50 years was calculated, taking into account current estimates of survival in women. As in other studies, the incidence of hip fracture increased exponentially with age. In-hospital death rate after hip fracture was low in this population (3.7%). Survival after hip fracture was correlated with age at hospitalization. About 12% of women alive at age 50 years will be hospitalized for a hip fracture at least once before they die. In this population, the incidence of hospitalization, in-hospital death rate, and lifetime probability of hip fracture were lower than in some other reports.

Distribution of lipoproteins and apolipoproteins in young adults The CARDIA Study

While there are many studies of the distribution of coronary heart disease risk factors in children, adolescents, and middle-aged adults, little information is available on this topic in young adults. The Coronary Artery Risk Development in Young Adults Study (CARDIA) examined 4858 men and women who fasted 10 or more hours, were ages 18 to 30, and were representative of black and white residents of four U.S. communities. Compared with white men, black men had higher age-adjusted mean levels of high density lipoprotein cholesterol (HDL-C) (6.7 mg/dl, p less than 0.001) and apolipoprotein A-l (apo A-l) (9.1 mg/dl, p less than 0.001) and lower concentrations of triglycerides (-19.7 mg/dl, p less than 0.001) and apolipoprotein B (apo B) (-3.3 mg/dl, p less than 0.001). Compared with white women, black women displayed higher concentrations of low density lipoprotein cholesterol (LDL-C) (5.7 mg/dl, p less than 0.001), apo A-l (2.6 mg/dl, p = 0.001), and apo B (3.0 mg/dl, p less than 0.001), but lower triglycerides (-5.8 mg/dl, p=0.001). Gender differences were more pronounced among whites: white men displayed lower mean levels of HDL-C and apo A-l (-9.2 and -7.3 mg/dl, p less than 0.001) and higher concentrations of LDL-C, triglycerides, and apo B (5.2 20.3, and 5.3 mg/dl, p less than 0.001) than white women. Attained level of education was significantly associated with a favorable lipoprotein/apolipoprotein profile, particularly among white women. These data indicate substantial variation in the distribution of lipoproteins and apolipoproteins in young adults, which may be important determinants of future coronary disease risk.

Ethnic differences in blood pressure, pulse rate, and related characteristics in young adults. The CARDIA study

This study examined ethnic differences in blood pressure and pulse rate in young adults to see whether the differences, if they exist, can be explained by differences in body mass index, lifestyle, psychological, and socioeconomic characteristics. Data used were from the baseline examination of the Coronary Artery Risk Development in (Young) Adults Study (CARDIA). CARDIA is a longitudinal study of lifestyle and evolution of cardiovascular disease risk factors in 5,116 young adults, black and white, men and women, aged 18-30 years, of varying socioeconomic status. Young black adults had higher mean systolic blood pressure and slightly higher mean diastolic blood pressure than young white adults. For both men and women, the blood pressure differences between blacks and whites tended to be greater for the age group 25-30 than for the age group 18-24 years. Among the variables studied, body mass index, duration of exercise on the treadmill, number of cigarettes smoked per day, and number of alcoholic drinks per week were consistently associated with blood pressure. The blood pressure differences were greatly reduced after adjusting for these variables. Black participants had lower mean pulse rate than white participants. The differences tended to be greater for the age group 18-24 than for the age group 25-30 years. Among the variables studied, only duration on treadmill and number of cigarettes smoked per day were consistently correlated with pulse rate. With adjustment for duration on treadmill, the differences in pulse rate increased. These results suggest that differences in ethnic pattern of blood pressures and pulse rate with age may be due in part to obesity, physical fitness, alcohol consumption, and cigarette smoking.

Obesity and cholecystectomy among women: implications for prevention

Almost all studies of the association of body mass with the risk of gallbladder disease have found that risk increases with obesity. Some studies report a nonlinear relationship of body mass to gallbladder disease risk, and some report that the association of excess body mass with increased risk of gallbladder disease is confined to younger women. We examined the association of body mass with the risk of cholecystectomy based on data from 14 years of follow-up of 16,638 women. The cholecystectomy rate was much greater in the highest quintile of Quetelet's body mass index than in other quintiles. The striking association of high rates of cholecystectomy with the highest quintile of Quetelet's body mass index was observed in each age group studied. The low incidence of cholecystectomy in young, thin women made the relative risk of cholecystectomy in women in the fifth quintile of body mass highest in women under 25 years of age. The observation that cholecystectomy rates are not linearly associated with obesity suggests that women in the highest quintiles of body mass could be considered a reasonable group in which strategies for prevention of gallbladder disease might be tested.

Increased risk of cholecystectomy in users of supplemental estrogen

We report the results of an analysis of information from a prospective cohort study of women examining the association between cholecystectomy and use of supplemental estrogens (never, current, and past use). There were 55 cases of cholecystectomy in those who had never used estrogen and 105 cases in those who had ever used estrogen. After adjustment for age, the relative risk of cholecystectomy in those who had ever used estrogen was 2.1 (95% confidence interval, 1.5-3.0). In women classified as current users based on information available in 1977, the relative risk of gallbladder disease was 2.7 (95% confidence interval, 1.8-4.0) and in past users as of this date, it was 1.6 (95% confidence interval, 1.1-2.5). When cases known to have reinitiated estrogen use after 1977 are removed from the numerator for past users and added to the numerator for current users, the relative estimate for past use decreased to 1.1 (95% confidence interval, 0.7-1.8), and the risk estimate for current use increased to 3.9 (95% confidence interval, 2.6-5.9). Although an increase in the risk of gallbladder disease in women using supplemental estrogens has been consistently observed in previous studies, the risk after cessation of use has received little attention but could be important. Our data suggest the possibility that the risk of gallbladder disease in estrogen users persists after use of the drug ceases. An increase in the risk of cholecystectomy in estrogen users that persists after drug use ends is plausible if estrogen-induced increases in the lithogenicity of bile cause gallstones to form during drug use and if these gallstones fail to dissolve even after bile lithogenicity returns to normal upon cessation of use. The effect of estrogen use on the gallbladder should be considered in weighing the net risk-benefit ratio of these drugs.

Vasectomy and the risk of prostatic cancer and benign prostatic hypertrophy

The incidence of prostatic disease (prostatic cancer and benign prostatic hypertrophy) was studied in a cohort of 5,332 vasectomized Kaiser Permanente Health Plan members, each matched with 3 nonvasectomized comparison subjects. Relative risks of 1.0 for prostatic cancer (68 cases, 95 per cent confidence limits 0.6 and 1.7) and 1.2 for benign prostatic hypertrophy (90 cases, 95 per cent confidence limits 0.7 and 1.8) were associated with vasectomy. In this study group the risk of prostatic disease was not altered by a history of vasectomy.

Noncontraceptive estrogens and mortality: long-term follow-up of women in the Walnut Creek Study

The effect of postmenopausal estrogen use on mortality is an important and controversial subject. To address it, we analyzed data from a ten- to 13-year mortality follow-up of the 3437 women enrolled in the Walnut Creek Contraceptive Drug Study who never used either estrogens or oral contraceptives and the 2656 women who used estrogens but not oral contraceptives. By 1983, 109 estrogen users and 110 nonusers had died. After adjusting for age, mortality in estrogen users (1.64 per 1000 woman-years) was lower than in nonusers (2.06 per 1000 woman-years) for all categories of cause of death except cancer. The lower mortality from accidents, suicide, and homicide in estrogen users has no plausible biologic explanation, and the observation suggests that life-style differences between estrogen users and nonusers account at least in part for their lower mortality. On the other hand, the observation that the relative risk of mortality due to cardiovascular disease was 0.5 in estrogen users, after adjustment for age and other cardiovascular disease risk factors, is suggestive.