High occupational physical activity and risk of ischaemic heart disease in women: the interplay with physical activity during leisure time.

BACKGROUND: Recent studies indicate that physically demanding work is a risk factor for heart disease among men, especially those with low or moderate physical activity during leisure time. Among women, present evidence is inconclusive. DESIGN: The design was a prospective cohort study. METHODS: This investigation in the Danish Nurse Cohort Study included 12,093 female nurses aged 45-64 years, who answered a self-report questionnaire on physical activity at work and during leisure time, known risk factors for ischaemic heart disease (IHD) and occupational factors at baseline in 1993. Information on the 15-year incidence of IHD was obtained by individual linkage in the National Register of Hospital Discharges to 2008. RESULTS: During follow-up 580 participants were hospitalised with IHD. A significant interaction between occupational and leisure time physical activity was found with the lowest risk of IHD among nurses with the combination of moderate physical activity at work and vigorous physical activity during leisure time. Compared to this group high physical activity at work was associated with a higher risk of IHD at all levels of physical activity during leisure time increasing from hazard ratio 1.75 (95% confidence interval (CI) 1.10-2.80) among nurses with vigorous physical activity during leisure time to 2.65 (95% CI 1.44-4.88) among nurses being sedentary during leisure time. CONCLUSIONS: This study among Danish nurses suggests that high physical activity at work is a risk factor for IHD among women. Vigorous physical activity during leisure time lowered but did not completely counteract the adverse effect of occupational physical activity on risk of IHD.

Validity of self-reported birthweight among middle-aged and elderly women in the Danish Nurse Cohort Study.

OBJECTIVE: To investigate the validity of self-reported birthweight among middle-aged and elderly women and to identify possible determinants of reporting accuracy. SETTING AND DESIGN: The Danish Nurse Cohort Study (DNCS), a prospective risk factor and hormone therapy study. POPULATION: Participants in the 1999 DNCS. METHODS: Self-reported exact and categorical birthweight data from the DNCS was compared with data from the Copenhagen School Health Records Register (CSHRR), which contains birthweight data. MAIN OUTCOME MEASURES: Accuracy of self-reported birthweight expressed as mean difference with limits of agreement, sensitivity, specificity, and positive and negative predictive values (PPV and NPV). RESULTS: Exact birthweight was available for 441 participants. The correlation coefficient was 0.83. The mean difference was -21 g and limits of agreement were -843 to 818 g. A total of 74% answered correctly within 250 g while 7% were more than 500 g in error. Categorical birthweight was available for 925 participants. A total of 87% reported the correct birthweight. Sensitivity and PPV were high for normal birthweight, whereas specificity and NPV were better for high and low birthweight (HBW and LBW). Multiple logistic regression analyses showed that HBW, LBW and being the daughter of a young mother decreased the accuracy of self-reported birthweight. CONCLUSIONS: Self-reported birthweight is a valid measure of actual birthweight among middle-aged and elderly women. Due to the lower accuracy of HBW and LBW, studies of the association between birthweight and chronic disease may underestimate the true effect of these weights.

A prospective study of the association between weight changes and self-rated health.

BACKGROUND: Obesity and self-rated health (SRH) are strong predictors of morbidity and mortality but their interrelation is sparsely studied. The aim of this study was to analyse the association between weight changes and changes in SRH among women. We also examined if poor SRH at baseline was associated with later weight gain. METHODS: The Danish Nurse Cohort Study is a prospective population study (1993-1999) and comprises 13,684 female nurses aged 44 to 69 years. Logistic regression analyses were used to examine the association between weight changes and changes in SRH. RESULTS: Women who gained weight during the study period had higher odds of reporting poorer self-rated health (Odds Ratio (OR): 1.18, 95% CI: 1.04-1.35). Weight loss among overweight women, did not result in an increase in self-rated health ratings, in fully adjusted analyses (0.96 (95% CI: 0.76-1.23). Poor self-rated health combined with normal weight at first examination was associated with higher odds of later weight gain (OR: 1.29, 95% CI: 1.10-1.51). CONCLUSION: Weight changes may result in lower SRH. Further, poor self-rated health at baseline seems to predict an increase in weight, among women without any longstanding chronic diseases. Future obesity prevention may focus on normal weight individuals with poor SRH.

Intentional weight loss and mortality among initially healthy men and women.

Most prospective observational studies suggest that weight loss increases the risk of premature death among obese individuals. This is surprising because clinical studies show that weight loss generally leads to overall improvements in cardiovascular risk factors. It is sometimes argued that the increased mortality observed with weight loss must depend on confounding or poor study designs. This review was conducted to summarize results from studies on intentional weight loss and mortality among healthy individuals, while carefully considering the designs and problems in these studies. Evaluation criteria with a rating scale were developed. Of the studies evaluated, two found decreased mortality with intentional weight loss, three found increased mortality, and four found no significant associations between intentional weight loss and total mortality. Thus, it is still not possible for health authorities to make secure recommendations on intentional weight loss. More studies designed to specifically address this issue are warranted.

Influence of health, lifestyle, working conditions, and sociodemography on early retirement among nurses: the Danish Nurse Cohort Study.

AIMS: The aim of the study was to analyze the relationship between health, lifestyle, work-related and sociodemographic factors, and older nurses' exit from the labor market to Post-Employment Wage (PEW). PEW is an early retirement scheme to make it possible for workers to retire at the age of 60. METHODS: The study was based on 5,538 nurses in the age of 51-59 who in 1993 completed a questionnaire on health, lifestyle, working environment, and sociodemographic factors. The survey information was combined with longitudinal data from the Danish Integrated Database for Labor Market Research compiled by Statistics Denmark. The follow-up period was from 1993 to 2002. RESULTS: Nurses who had poor self-rated health were more likely to join PEW compared with nurses who considered their health as good (HR 1.28, 95% CI 1.16-1.41). Low job influence, high workload, and physical job demands only marginally increased the probability of retiring. Nurses who have relatively low gross incomes had an increased probability of entering PEW compared with nurses with relatively high gross incomes (HR 1.60, CI 1.43-1.79). Having a spouse increased the probability of joining PEW, especially having a spouse who had retired or was unemployed. CONCLUSIONS: The retirement age among nurses is influenced by a number of sociodemographic, work-related, and health-related factors. Poor health, low income, living outside the Copenhagen area, being married, having a spouse who is outside the labor force, and working in the daytime are all predictors of early retirement among nurses. Poor working environment only marginally increased the probability of retiring early.

Comparison of lifestyle and health among Danish nurses and the Danish female population: is it possible to generalize findings from nurses to the general female population?

AIMS: To generalize findings from a nursing population to the general female population, the aim of this study was to compare lifestyle and health among Danish female nurses with that among Danish women. Furthermore, the aim was to compare lifestyle and health among Danish female nurses with women belonging to the same socio-economic group as nurses. METHODS: Danish females above the age of 44 in 1999 (n = 22,715) were compared with a group of women from the Danish Health and Morbidity Survey conducted in 2000 (n = 4,445). Age standardized risk ratios (SRR) with 95% confidence intervals were calculated to compare the two groups. RESULTS: Nurses smoke less (SRR 0.74, CI: 0.70-0.78) and are more physically active (SRR 2.53, CI: 2.31-2.77) when compared with the general female population. A higher percentage of nurses consume five drinks or more on a weekday compared with the general female population (SRR 2.68, CI: 2.25-3.19). When comparing nurses with women belonging to the same socio-economic group, these differences are also found to be statistically significant, but no differences are found according to overweight/obesity, self-reported health and limitations in daily activities when nurses are compared with women belonging to the same socio-economic group. CONCLUSIONS: In general, Danish nurses have a healthier lifestyle than other Danish women. In future studies, differences and similarities in lifestyle and health between nurses and other women should be considered when generalizing findings from Danish nurses to the Danish female population.

Influence of lifestyle, health, and work environment on smoking cessation among Danish nurses followed over 6 years.

BACKGROUND: The purpose of this study was to examine the influence of lifestyle, health, and work environment on smoking cessation among Danish nurses age 45-66 years over a 6-year period from 1993-1999. METHODS: Data derive from the Danish Nurse Cohort Study; a prospective cohort established in 1993 when all Danish female nurses 45+ years old and members of the Danish Nurses Association were mailed a questionnaire. The cohort was followed up 6 years later in 1999. In total, 12,980 responded to questions concerning smoking status in both the 1993 and 1999 surveys. This study deals with the 4713 women (36%) who reported smoking at baseline. Smoking cessation was based on self-report. RESULTS: At follow-up in 1999, 24% reported that they no longer smoked. Low prior tobacco consumption at baseline, high fresh fruit consumption, high blood pressure, working day shifts, having low physical job strain, perceiving influence on one's own work, and partner's socio-economic status (as measured by most recent occupation) were associated with successful smoking cessation. CONCLUSION: The findings from this study highlight the importance of various factors, including lifestyle, health status, and aspects of one's work environment, on successful efforts at smoking cessation.

Lifestyle factors and choice of hormone replacement therapy among Danish nurses.

BACKGROUND: Studies have found that women who use hormone replacement therapy (HRT) are healthier or report better health than non-users. This study examines the association between lifestyle factors, self-reported health and the use of HRT in Danish female nurses above the age of 50 years. METHODS: Postal questionnaires were used for data collection. Two cohorts were examined, a younger including women between 50 and 59 years and an older including women of 60 years and above. RESULTS: Of the 14,071 nurses included, 5,528 (39%) reported ever using HRT. In both cohorts, ever using HRT was positively associated (odds ratio > 1) with intake of vitamin supplements, alcohol consumption at weekends, consulting a physician, use of medicine, and previous use of oral contraceptives. Only a few differences were found between former and current users of HRT. A highly significant association was found between ever using HRT and self-reported poor health. CONCLUSIONS: In this study use of HRT was not found to be associated with a particularly healthy lifestyle or better health. Therefore, these factors should be specifically considered in studies evaluating the effect of HRT.