Tobacco smoking and risk of hip fracture in men and women

BACKGROUND: Previous findings suggest that tobacco smoking increases the risk of hip fracture in women. A similar adverse effect of smoking is suspected to be present in men, but bone mineral density studies have raised the concern that men may be more sensitive to the deleterious effect of smoking on bone than women. In this study we prospectively determined the influence of current, previous, and cumulative smoking history on risk of hip fracture in men and women and addressed the issue of possible gender difference in the susceptibility to tobacco smoking. METHODS: Pooled data from three population studies conducted in Copenhagen with detailed information on smoking habit. A total of 13,393 women and 17,379 men, initially examined between 1964 and 1992, were followed until 1997 for first admission due to hip fracture. The relative risks (RR) of hip fracture associated with smoking were estimated by means of multiplicative Poisson regression models. RESULTS: During follow-up, 722 hip fractures were identified in women, and 447 in men. After adjustment for potential confounders, including body mass index, female current smokers had an RR of hip fracture of 1.36 (95% CI: 1.12-1.65) and male smokers 1.59 (95% CI: 1.04-2.43) relative to never smokers. In both sexes, the RR of hip fracture gradually increased by current and accumulated tobacco consumption. The RR were consistently higher in men than in women, but the test for interaction between sex and tobacco smoking was insignificant. After 5 years, male ex-smokers had an adjusted RR of 0.73 (95% CI: 0.55-0.98) relative to current smokers, while no significant decrease in risk was observed in female ex-smokers (RR = 0.91; 95% CI: 0.72-1.17)). Approximately 19% of all hip fractures in the present study population were attributable to tobacco smoking. CONCLUSION: Tobacco smoking is an independent risk factor for hip fracture in men and women, and there appears to be no gender differences in smoking related risk. Smoking cessation reduces the risk of hip fracture in men after 5 years, while the deleterious effect of smoking seems to be more long-lasting in female ex-smokers.     

Systematic review of type 1 and type 2 diabetes mellitus and risk of fracture

The authors conducted a systematic review of published data on the association between diabetes mellitus and fracture. The authors searched MEDLINE through June 2006 and examined the reference lists of pertinent articles (limited to studies in humans). Summary relative risks and 95% confidence intervals were calculated with a random-effects model. The 16 eligible studies (two case-control studies and 14 cohort studies) included 836,941 participants and 139,531 incident cases of fracture. Type 2 diabetes was associated with an increased risk of hip fracture in both men (summary relative risk (RR) = 2.8, 95% confidence interval (CI): 1.2, 6.6) and women (summary RR = 2.1, 95% CI: 1.6, 2.7). Results were consistent between studies of men and women and between studies conducted in the United States and Europe. The association between type of diabetes and hip fracture incidence was stronger for type 1 diabetes (summary RR = 6.3, 95% CI: 2.6, 15.1) than for type 2 diabetes (summary RR = 1.7, 95% CI: 1.3, 2.2). Type 2 diabetes was weakly associated with fractures at other sites, and most effect estimates were not statistically significant. These findings strongly support an association between both type 1 and type 2 diabetes and increased risk of hip fracture in men and women.     

Calcium intake and hip fracture risk in men and women: a meta-analysis of prospective cohort studies and randomized controlled trials

BACKGROUND: The role of total calcium intake in the prevention of hip fracture risk has not been well established. OBJECTIVE: The objective of the study was to assess the relation of calcium intake to the risk of hip fracture on the basis of meta-analyses of cohort studies and clinical trials. RESULTS: In women (7 prospective cohort studies, 170,991 women, 2,954 hip fractures), there was no association between total calcium intake and hip fracture risk [pooled risk ratio (RR) per 300 mg total Ca/d = 1.01; 95% CI: 0.97, 1.05]. In men (5 prospective cohort studies, 68,606 men, 214 hip fractures), the pooled RR per 300 mg total Ca/d was 0.92 (95% CI: 0.82, 1.03). On the basis of 5 clinical trials (n = 5666 women, primarily postmenopausal, plus 1074 men) with 814 nonvertebral fractures, the pooled RR for nonvertebral fractures between calcium supplementation (800-1600 mg/d) and placebo was 0.92 (95% CI: 0.81, 1.05). On the basis of 4 clinical trials with separate results for hip fracture (6,504 subjects with 139 hip fractures), the pooled RR between calcium and placebo was 1.64 (95% CI:1.02, 2.64). Sensitivity analyses including 2 additional small trials with <100 participants or per-protocol results did not substantially alter results. CONCLUSIONS: Pooled results from prospective cohort studies suggest that calcium intake is not significantly associated with hip fracture risk in women or men. Pooled results from randomized controlled trials show no reduction in hip fracture risk with calcium supplementation, and an increased risk is possible. For any nonvertebral fractures, there was a neutral effect in the randomized trials.     

Risk factors for proximal humerus, forearm, and wrist fractures in elderly men and women: the Dubbo Osteoporosis Epidemiology Study

Fractures of the proximal humerus, forearm, and wrist account for approximately one third of total osteoporotic fractures in the elderly. Several risk factors for these fractures were evaluated in this prospective study of 739 men and 1,105 women aged > or =60 years in Dubbo, Australia. During follow-up (1989-1996), the respective incidences of humerus and of forearm and wrist fractures, per 10,000 person-years, were 22.6 and 33.8 for men and 54.8 and 124.6 for women. Independent predictors of humerus fracture were femoral neck bone mineral density (FNBMD) (relative risk (RR) = 2.3, 95% confidence interval (CI): 1.2, 4.5) in men and FNBMD (RR = 2.4, 95% CI: 1.7, 3.5) and height loss (RR = 1.1, 95% CI: 1.0, 1.2) in women. For forearm and wrist fractures, risk factors were FNBMD (men: RR = 1.5, 95% CI: 1.0, 2.3; women: RR = 1.5, 95% CI: 1.2, 1.9) and height loss (men: RR = 1.2, 95% CI: 1.0, 1.3; women: RR = 1.1, 95% CI: 1.0, 1.2). In addition, dietary calcium (men: RR = 2.0, 95% CI: 1.0, 3.6) and a history of falls (women: RR = 1.9, 95% CI: 1.4, 2.6) were also significant. These data suggest that elderly men and women largely share common risk factors for upper limb fractures and that FNBMD is the primary risk factor.     

Associations of birth weight and length, childhood size, and smoking with bone fractures during growth: evidence from a birth cohort study

Little information exists on risk factors associated with bone fractures during childhood and adolescence. This 1972/1973-1990/1991 New Zealand study examined the influence of birth size, height and weight throughout growth, smoking, breastfeeding, and sports participation on the risk of fracture in participants of the Dunedin Multidisciplinary Health and Development Study. Information on height, weight, fracture status, and lifestyle was collected at birth and at ages 3, 5, 7, 9, 11, 13, 15, and 18 years from parents and/or participants. Study members sustained 229 (girls) and 393 (boys) fractures between birth and age 18 years. Fracture risk was elevated (per standard deviation unit increase) in relation to birth length (prepubertal fractures only) (risk ratio (RR) = 1.28, 95% confidence interval (CI): 1.04, 1.58), weight at age 3 years (RR = 1.14, 95% CI: 1.03, 1.27), weight from ages 5 to 18 years (RR = 1.15, 95% CI: 1.03, 1.28), height at age 3 years (RR = 1.13, 95% CI: 1.01, 1.26), and height from ages 5 to 18 years (RR = 1.13, 95% CI: 1.02, 1.24). Birth weight, maternal smoking, breastfeeding, and sports participation had no significant effect on fracture risk. However, for teenagers, personal daily smoking increased the risk of fracture (RR = 1.43, 95% CI: 1.05, 1.95). The authors concluded that tall and heavy children had an increased risk of fracture, as did adolescents who smoked regularly.     

Mental distress and risk of hip fracture. Do broken hearts lead to broken bones?

OBJECTIVE: Mental distress may entail increased risk of hip fracture, but it is uncertain whether the effect consists solely of an indirect effect through use of medication, or whether it is also mediated through other mechanism. The purpose of this study was to examine the association between mental distress and risk of hip fracture in women, adjusted for medication (that is, use of tranquillisers/sedatives or hypnotics). DESIGN: A three year follow up of hip fracture was conducted on 18,612 women, consisting of 92.5% of all women aged 50 years or older in a Norwegian county. Three hundred and twenty nine suffered a hip fracture. A mental distress index was based on questions about life dissatisfaction, nervousness, loneliness, sleep disorders, troubled and uneasy feelings, depression and impairment attributable to psychological complaints. Relative risk with 95% confidence intervals (CI) of hip fracture with respect to mental distress were controlled for medication, age, body mass index (BMI), smoking, physical inactivity, and physical illness by means of Cox regression. RESULTS: The 10% of women with the highest mental distress had more than twofold increased risk of hip fracture compared with the 10% of women with the lowest mental distress, after adjustment for age and medication. The relative risk was 1.95 (95% CI 1.2, 3.3) after additional control for BMI, smoking, physical inactivity, and physical illness. The relative risk of hip fracture for daily users of medication compared with never users was 2.1 (95% CI 1.6, 2.9). After adjusting for mental distress it was 1.5 (95% CI 1.0, 2.2). CONCLUSIONS: Risk of hip fracture was positively related to mental distress, also after adjustment for medication use. The effect of tranquillisers/sedatives or hypnotics on hip fracture risk may be overestimated in studies with no adjustments for mental distress.     

Exercise and other factors in the prevention of hip fracture: the Leisure World study

As part of a prospective study begun in 1981, we evaluated 8,600 postmenopausal women and 5,049 men residing in a southern California retirement community for risk factors for hip fracture. Incidence rates were twice as high in women as in men, but in both sexes the rates nearly doubled every 5 years between 70 and 90 years. Active exercise was strongly and negatively associated with hip fracture risk in both sexes; the age-adjusted relative risk was 0.6 and 0.5 for females and males, respectively, for 1 or more hours of exercise per day compared with less than 1/2 hour of exercise. A high body mass index (upper tertile of weight divided by height squared) was associated with a strong reduction in hip fracture risk for females (RR = 0.5). Current cigarette smokers had a significantly increased risk (RR = 1.8 and RR = 2.2 for females and males, respectively) compared with never-smokers, but the risk for past smokers was not different from that of lifetime nonsmokers. Other factors related to reduced hip fracture risk in women were high parity, late age at menarche, and long menstrual cycle length. These age-adjusted relative risk estimates did not change materially in multivariate analysis when adjusted simultaneously for age, active exercise, body mass, smoking, and, for women, age at menarche and number of children. Among estrogen users, the lowest risk of hip fracture was observed for recent users (RR = 0.8), while users who had stopped estrogen use 15 or more years ago had a relative risk of 1.1, suggesting that the protective effect of estrogen dissipates after many years since cessation of estrogen therapy.     

Tobacco smoking and alcohol consumption as risk factors for glioma: a case-control study in Melbourne, Australia.

OBJECTIVE: To investigate possible associations between tobacco smoking and alcohol consumption and the risk of adult glioma. DESIGN: This was a population based, case-control study. Relative risks (RR) were estimated using logistic regression analysis. SETTING: Melbourne, Australia. PARTICIPANTS: These comprised 416 case subjects (166 women, 250 men), 66% of those eligible; and 422 control subjects (170 women, 252 men), 43.5% of those potentially eligible. RESULTS: There was no increase in risk of glioma with having ever smoked tobacco (RR 1.29, 95% CI 0.95, 1.75) for all subjects, adjusted for age, a reference date, and gender. There was a slight increase in risk for men (RR 1.64, 95% CI 1.1, 2.45), but not for women (RR 0.99, 95% CI 0.62, 1.62). For men, there was no increase in risk with increasing pack-years of cigarette smoking, but the risk was significantly increased in subjects who had smoked for less than 10 years. There was no increase in risk associated with having ever drunk alcohol for all subjects (RR 0.96, 95% CI 0.67, 1.37), women (RR 0.69, 95% CI 0.4, 1.15) or men (RR 1.40, 95% CI 0.81, 2.43). CONCLUSIONS: This study does not support an association between either tobacco smoking or alcohol consumption and glioma. The pattern of risk associated with tobacco smoking in men appears inconsistent with a causal role, and may be due to chance, response bias, or uncontrolled confounding.     

Serum cholesterol--risk factor for coronary disease mortality in younger and older blacks and whites. The Charleston Heart Study, 1960-1988.

Serum total cholesterol (> or = 6.7 mmol/L) measured in 1960 in the Charleston Heart Study cohort was found to be a risk for mortality from coronary heart disease during the period of 1960 to 1988 in white men (relative risk [RR] 1.5; 95% confidence interval [CI]: 1.1, 2.2), white women (RR 1.7; 95% CI: 1.1, 2.7), and black women (RR 1.6; 95% CI: .9, 2.9) after age, systolic blood pressure, smoking status, education level, obesity, and diabetes were considered. For black men, the relative risk was .96 (95% CI, .39, 2.39). Only among white women was the relative risk (RR 2.4; 95% CI, 1.2, 4.5) increased among those in the older ages (55 to 74) in 1960. The evidence for cholesterol as a risk factor for coronary disease mortality in black men is inconclusive and requires further study.     

Leisure-time physical activity levels and changes in relation to risk of hip fracture in men and women.

The authors prospectively studied the effect of leisure-time physical activity level on hip fracture risk along with the influence of within-subject changes in activity levels, while taking possible confounding by other health behaviors and poor health into account. Analyses were based on pooled data from three population studies conducted in Copenhagen, Denmark. Among 13,183 women and 17,045 men, 1,121 first hip fractures were identified during follow-up. In comparison with being sedentary, the relative risk (RR) of hip fracture associated with being moderately physically active 2-4 hours per week was 0.72 (95% confidence interval (CI): 0.59, 0.89) in women and 0.75 (95% CI: 0.55, 1.03) in men after adjustment for confounders. Being in the most active leisure activity category did not decrease the risk of hip fracture further. Adjustment for poor health affected the risk estimates only modestly. Subjects who, during follow-up, reduced their physical activity level from the highest or the intermediate activity level to a sedentary level had a higher risk of hip fracture than did those who remained moderately physically active at the intermediate level (multivariate adjusted RR = 2.19, 95% CI: 1.00, 4.84 and RR = 1.89, 95% CI: 1.21, 2.95, for reduction from the highest and intermediate levels, respectively). There was no evidence of a fracture-protective effect from increasing physical activity. In conclusion, moderate levels of physical activity appear to provide protection against later hip fracture. Decline in the physical activity level over time is an important risk factor for hip fracture.     

Cohort study on risk factors for subarachnoid hemorrhage among Japanese men and women

PURPOSE: To examine the risk factors for subarachnoid hemorrhage, for few prospective data have been available on risk factors of subarachnoid hemorrhage among Japanese. METHODS: A 9.4-year cohort study was conducted on 12,372 men and women, aged 40-69 years, free of history of stroke in six communities in Japan. RESULTS: During the follow-up, seventy-one incidents of subarachnoid hemorrhage occurred. After adjusting for age, serum total cholesterol, body mass index, history of diabetes mellitus, blood pressure category and drinking category, current smokers had a significantly increased risk of subarachnoid hemorrhage compared with 'never-smokers': multivariate relative risk (RR) [95% confidence interval (95% CI)] = 3.1(1.4-6.9) for women, 1.5(0.4-5.3) for men and 2.7(1.3-5.5)for men and women. Hypertensives had a significantly increased risk of subarachnoid hemorrhage compared with normotensives: multivariate RR(95% CI) = 3.1(1.6-6.0) for women, 4.3(1.5-12.0) for men and 3.4(2.0-5.9) for men and women. For men, heavy drinkers (> = 69 g per day ethanol), had a significantly increased risk of subarachnoid hemorrhage compared with 'never-drinkers': multivariate RR(95% CI) = 4.3(1.1-16.8). For women, the relationship between heavy drinking and risk was not examined due to the small number of heavy drinkers (n = 13). Multivariate RR(95% CI) for men who smoked currently and drank heavily compared with men who did not smoke currently nor drink heavily was 6.0(1.8-20.1). Multivariate RR(95% CI) for hypertensive men who drank heavily compared with normotensive or borderline hypertensive men who did not drink heavily was 13.0(3.9-43.9). Multivariate RR(95% CI) for hypertensive men and women who smoked currently compared with normotensive or borderline hypertensive men and women who did not smoke currently was 6.1(1.3-28.7) for men and 6.3(1.4-28.0) for women. Furthermore, the combination of smoking, hypertension and heavy drinking raised the risk of subarachnoid hemorrhage substantially: multivariate RR(95% CI) = 17.5(3.4-90.2). CONCLUSION: Smoking and hypertension appeared to increase the risk of subarachnoid hemorrhage. For men, although the association of smoking with the risk of subarachnoid hemorrhage was weak compared with women, the combination of smoking, hypertension and heavy drinking increased the risk substantially. For women, smoking appeared to be an independent risk of subarachnoid hemorrhage, and the combination of smoking and hypertension increased the risk in additive fashion.     

Hormone replacement therapy and hip fracture risk: effect modification by tobacco smoking, alcohol intake, physical activity, and body mass index

The authors prospectively studied the overall effect of hormone replacement therapy (HRT) on hip fracture risk and the effect modification by behavioral habits and body mass index. A total of 6,159 postmenopausal women from the Copenhagen Center for Prospective Population Studies, Copenhagen, Denmark, with initial examination in 1976-1978 were followed until 1993. During follow-up 363 hip fractures were identified. Women who reported current use of HRT had a lower risk of hip fracture as compared with women who were nonusers (relative risk (RR) = 0.71; 95 percent confidence interval (CI): 0.50, 1.01). Use of HRT was associated with a lower risk of hip fracture in former (RR = 0.55; 95 percent CI: 0.22, 1.37) and current (RR = 0.61; 95 percent CI: 0.38, 0.99) smokers but not in never smokers (RR = 1.10; 95 percent CI: 0.60, 2.03). HRT was also associated with lower risk of hip fracture among alcohol drinkers (RR = 0.36; 95 percent CI: 0.14, 0.90) and among sedentary women (RR = 0.42; 95 percent CI: 0.18, 0.98) but not among nondrinkers (RR = 0.99; 95 percent CI: 0.61, 1.61) and physically active women (RR = 0.92; 95 percent CI: 0.42, 2.04). There was no evidence of interaction between use of HRT and body mass index. In conclusion, the protective effect of HRT on hip fracture appears to be strongest in women who ever smoked, in women who drink alcohol, and in women who are sedentary. The results suggest that history of behavioral habits offers important information concerning the probable degree of protection against hip fracture afforded by HRT.     

Physical activity and risk of cancer in the NHANES I population.

We studied the relation between self-reported physical activity and cancer in the first National Health and Nutrition Examination Survey (NHANES I) cohort, originally examined between 1971-75, and followed prospectively through the Epidemiologic Follow-up Study (NHEFS), conducted between 1982-84. Among 5,138 men and 7,407 women 25-74 years old, for nonrecreational activity we observed increased risk of cancer among inactive individuals compared to very active persons (for men, relative risk [RR] 1.8, 95% confidence interval [CI] = 1.4, 2.4; for women RR 1.3, 95% CI = 1.0, 1.8). These findings were unchanged after adjustment for cigarette smoking, body mass index (BMI), and other potential confounders. Sites which demonstrated stronger inactivity-cancer associations included colorectum (RR 1.6, 95% CI = 0.7, 3.5) and lung (RR 1.6; 95% CI = 1.2, 3.5) among men, and breast (post-menopausal) (RR 1.7; 95% CI = 0.8, 2.9) and cervix (RR 5.2; 95% CI = 1.4, 14.5) among women, although these findings for women were based on relatively few cases. The association between inactivity and cancer was greater among persons of moderate (or lower) BMI, those cases occurring three or more years after baseline, and, in women, those more than 60 years old. In contrast, recreational exercise showed little relation to cancer, with the exception of prostate cancer. The results suggest that inactive individuals are at increased risk of cancer.     

Leisure time physical activity and risk of non-vertebral fracture in men and women aged 55?years and older: the Troms? Study

Our aim was to examine associations between leisure time physical activity and risk of non-vertebral fractures in men and women aged ≥55 years, with focus on the anatomical fracture location. Self-reported physical activity was registered in 3,450 men and 4,072 women aged 55-97 years at baseline in the Troms? Study, Norway, in 1994-1995. Non-vertebral fractures were registered through December 31, 2009. During 75,546 person-years at risk, 1,693 non-vertebral fractures were identified. Risk of any non-vertebral fracture decreased with increasing physical activity level in men (P (trend) = 0.006) and non-significantly in women (P (trend) = 0.15), after adjustment for age, body mass index, height, smoking, and previous fracture. The reduced fracture risk was due to a reduced risk in the weight-bearing skeleton, particular at the hip, whereas risk of fracture in the non-weight-bearing skeleton was not related to physical activity. At weight-bearing sites, an inverse relationship between physical activity and fracture risk was present in both sexes (P (trend) ≤ 0.013). Compared with sedentary subjects, the most active men and women had respectively 37% (HR = 0.63, 95% CI: 0.45, 0.88) and 23% (HR = 0.77, 95% CI: 0.62, 0.95) reduced fracture risk in the weight-bearing skeleton. Physical activity is associated with reduced fracture risk at weight-bearing sites, with no associations at non-weight-bearing sites, in both sexes. Habitual physical activity is an important amendable approach to prevent hip fracture.     

Chronic obstructive pulmonary disease and mortality following hip fracture: a population-based cohort study

Introduction: Mortality rates after hip fracture have not declined in 20 years. We assessed the impact of chronic obstructive pulmonary disease (COPD) on mortality after hip fracture, and compared mortality in this cohort to persons without hip fracture in a population-based prospective cohort study. Methods: Using Danish health care registries, we identified persons ≥40 years old with first-time hospitalization for hip fracture between 1/1/1998 and 1/31/2003. Hospitalization for COPD was assessed from hospital discharge registries. Using Cox regression, we computed relative risks (RR) and 95% confidence intervals (CI) for mortality endpoints among persons with COPD compared to persons without COPD. Mortality following hip fracture was also compared to age and gender matched controls without hip fracture. Results: We identified 11, 985 persons with first-time hospitalization for hip fracture; 771 (6.4%) had a diagnosis of COPD. Average follow up was 22 months. Compared to persons without COPD, mortality following hip fracture in persons with COPD was RR = 1.58 (95% CI 1.30–1.90) at 30 days, RR = 1.52 (95% CI 1.30–1.77) at 90–days, RR = 1.58 (95% CI 1.40–1.78) at 1 year, and RR = 1.71 (95% CI 1.55–1.88) overall. The 1-year mortality in persons with hip fracture and COPD was approximately 3–5 times greater than in controls without hip fracture. Conclusions: In this cohort, persons with COPD have a 60–70% higher risk of death following hip fracture than those without COPD. In addition, hip fracture and COPD increased 1-year mortality 3–5 times that of persons without hip fracture. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Hip fractures in women with breast cancer

The authors investigated whether the incidence of first hip fracture, an indicator of osteoporosis, is lower in breast cancer patients, who are assumed to have higher levels of endogenous estrogens, than in other women. A population-based Swedish cohort comprising 9,673 women with invasive breast cancer diagnosed from 1958 through 1983 was followed up with respect to the occurrence of a first hip fracture during the period 1965-1983. Overall, the number of observed acute fractures (n = 387) was slightly higher than expected (n = 348.6) (standardized incidence ratio (SIR) = 1.1, 95% confidence interval (CI) 1.0-1.2). Risk for trochanteric fractures was slightly higher than expected (SIR = 1.2, 95% CI 1.0-1.4), but risk for cervical fractures was not (SIR = 1.0, 95% CI 0.9-1.1). Risk for trochanteric fracture decreased with increasing age at breast cancer diagnosis, reaching standardized incidence ratios close to unity after the age of 70 years. Duration of follow-up appeared to be unrelated to the risk of either type of fracture. The authors conclude that the incidence of first hip fracture is not lower in breast cancer patients than in other women.     

Gender differences in the healthy worker effect among synthetic vitreous fiber workers

The aim of this study was to determine whether the healthy worker effect and its component parts operate similarly for women and men. A cohort of workers from 14 synthetic vitreous fiber factories in seven countries, employed for at least 1 year between 1933 and 1977 and followed up to the early 1990s, included 375 deaths and 53,608 person-years among females and 2,568 deaths and 210,073 person-years among males. Standardized mortality ratios for all-cause and circulatory diseases were adjusted for country, age, calendar time, and gender. In addition, internal comparisons were adjusted for time since hire and employment status. The analyses addressed the following: 1) the healthy hire effect, 2) the time since hire effect, and 3) the healthy worker survivor effect. In this cohort, an overall healthy worker effect was not present in either gender. The healthy hire effect, based on standardized mortality ratios for years 1-4 since hire, was observed in males (standardized mortality ratio (SMR) = 0.8; 95% confidence interval (CI): 0.7, 1.0) but was less in females (SMR = 0.9; 95% CI: 0.5, 1.6). The relative risks increased slightly with time since hire in males but not in females. Higher mortality ratios were seen among those leaving employment than among those who remained actively employed; however, this effect was substantially greater for women (relative risk (RR) = 3.4; 95% CI: 1.8, 6.3) than men (RR = 1.8; 95% CI: 1.5, 2.1). The gender difference for active versus inactive status was stronger up to age 60 (men: RR = 1.7; 95% CI: 1.4, 2.0; women: RR = 3.6; 95% CI: 1.8, 7.1) than above that age. In conclusion, it appears that there is a stronger selection of healthy men than women into the workforce, while health-related selection out of the workforce is stronger for women than men.     

Body mass index and colon cancer mortality in a large prospective study

Obesity has been reported to increase the risk of colon cancer, especially in men. The authors examined this relation in the American Cancer Society's Cancer Prevention Study II, a nationwide mortality study of US adults. After 12 years of follow-up, 1,616 deaths from colon cancer in women and 1,792 in men were observed among 496,239 women and 379,167 men who were cancer free at enrollment in 1982. The authors used Cox proportional hazards analyses to control for effects of age, race, education, smoking, exercise, alcohol, parental history of colon cancer, fat intake, vegetable and grain intake, aspirin use and, in women, estrogen replacement therapy. In men, death rates from colon cancer increased across the entire range of body mass index (BMI). The rate ratio was highest for men with BMI > or =32.5 (rate ratio (RR) = 1.90, 95% confidence interval (CI): 1.46, 2.47) compared with men with BMI between 22.00 and 23.49. In women, a weaker association was seen in the three BMI categories of 27.5-29.9 (RR = 1.26, 95% CI: 1.03, 1.53), 30.0-32.4 (RR = 1.37, 95% CI: 1.09, 1.72), and > or =32.5 (RR = 1.23, 95% CI: 0.96, 1.59). These prospective data support the hypothesis that obesity increases the risk of colon cancer death and that the relation is stronger and more linear in men than in women.     

Smoking and invasive cervical cancer risk. Results from a case-control study

The association between cigarette smoking and risk of invasive cervical cancer was investigated in a case-control study conducted in four hospitals in Leipzig, German Democratic Republic in 1983-1985. Analyses were based on 225 women aged 64 years or younger with newly diagnosed invasive cervical cancer and 435 age-matched controls with orthopedic or skin diseases. The crude relative risk of invasive cervical cancer was significantly elevated for women who had ever smoked (relative risk (RR) = 1.5, 95% confidence interval (CI) = 1.1-2.1). Adjustment for number of sexual partners reduced the risk to RR = 1.2 (95% CI = 0.8-1.6). Furthermore, the risk for smokers depended significantly on number of sexual partners (p less than 0.05) and was increased only among women with no partner or one partner (RR = 2.7, 95% CI = 1.2-6.1).     

Smoking cessation and risk of cataract extraction among US women and men.

Although the observational evidence linking cigarette smoking with risk of senile cataract is well-established, it is unclear whether any benefit is obtained from quitting smoking. Therefore, in this study, the authors examined the association between time since quitting smoking and incidence of cataract extraction in women and men enrolled in the Nurses' Health Study and the Health Professionals Follow-up Study, respectively. There were 4,281 incident physician-confirmed cases of cataract and 1,038,493 accumulated person-years of follow-up. Compared with current smokers, former smokers who had quit smoking 25 or more years previously had a 20% lower risk of cataract extraction after adjustment for age, average number of cigarettes smoked per day, and other potential risk factors (relative risk (RR) = 0.80, 95% confidence interval (CI): 0.71, 0.91). However, risk among past smokers did not decrease to the level seen among never smokers (for never smokers, RR = 0.64, 95% CI: 0.52, 0.79). The observed relation was similar when data were examined by cataract subtype (>25 years since quitting vs. current smoking: primarily nuclear cataract, RR = 0.82, 95% CI: 0.68, 0.97; primarily posterior subcapsular cataract, RR = 0.90, 95% CI: 0.71, 1.13). These findings suggest that any healing from damage due to cigarette smoking occurs at a very modest pace, and they emphasize the importance of never starting to smoke or quitting early in life.