Bernt Lindahl

Is there an association between shift work and having a metabolic syndrome? Results from a population based study of 27 485 people

OBJECTIVES To explore how metabolic risk factors for cardiovascular disease (CVD) differ between shift workers and day workers in a defined population. Shift work has been associated with an increased risk of CVD. Risk factors and causal pathways for this association are only partly known. METHODS A working population of 27 485 people from the Västerbotten intervention program (VIP) has been analysed. Cross sectional data, including blood sampling and questionnaires were collected in a health survey. RESULTS Obesity was more prevalent among shift workers in all age strata of women, but only in two out of four age groups in men. Increased triglycerides (>1.7 mmol/l) were more common among two age groups of shift working women but not among men. Low concentrations of high density lipoprotein (HDL) cholesterol (men<0.9 and women<1.0 mmol/l) were present in the youngest age group of shift workers in both men and women. Impaired glucose tolerance was more often found among 60 year old women shift workers. Obesity and high triglycerides persisted as risk factors in shift working men and women after adjusting for age and socioeconomic factors, with an OR of 1.4 for obesity and 1.1 for high triglyceride concentrations. The relative risks for women working shifts versus days with one, two, and three metabolic variables were 1.06, 1.20, and 1.71, respectively. The corresponding relative risks for men were 0.99, 1.30, and 1.63, respectively. CONCLUSIONS In this study, obesity, high triglycerides, and low concentrations of HDL cholesterol seem to cluster together more often in shift workers than in day workers, which might indicate an association between shift work and the metabolic syndrome.

Cardiovascular disease and diabetes in the Northern Sweden Health and Disease Study Cohort - evaluation of risk factors and their interactions.

The purpose of this paper is, first, to describe the organization, sampling procedures, availability of samples/database, ethical considerations, and quality control program of the Northern Sweden Health and Disease Study Cohort. Secondly, some examples are given of studies on cardiovascular disease and diabetes with a focus on the biomarker programme. The cohort has been positioned as a national and international resource for scientific research.

Body mass index and cancer : Results from the Northern Sweden Health and Disease Cohort

Excess weight has been associated with increased risk of cancer. The effect of body mass index (BMI, kg/m2) on overall cancer risk and on risk of developing several common cancer types was examined in a population‐based cohort study. Height and weight measurements were available for 35,362 women and 33,424 men recruited in the Northern Sweden Health and Disease Cohort between 1985 and 2003. Among cohort members, 2,691 incident cancer cases were identified. The association of BMI with cancer risk was examined using Poisson regression. Women with BMI > 27.1 (top quartile) had a 29% higher risk of developing any malignancy compared to women with BMI of 18.5–22.2 (lowest quartile), which increased to 47% in analysis limited to nonsmokers. Analyses according to WHO cut‐off points showed that obese women (BMI ≥ 30) had a 36% higher risk of cancer than women with BMI in the normal range (18.5–25). Individual cancer sites most strongly related to obesity were endometrium (risk for top quartile = 3.53, 95% confidence interval 1.86–7.43), ovary (2.09, 1.13–4.13) and colon (2.05, 1.04–4.41). BMI was inversely related to breast cancer occurring before age 49 (0.58, 0.29–1.11, ptrend < 0.04). In men, there was no association of BMI with overall cancer risk. Obese men (BMI ≥ 30), however, were at increased risk of developing kidney cancer (3.63, 1.23–10.7) and, after exclusion of cases diagnosed within 1 year of recruitment, colon cancer (1.77, 1.04–2.95). Our study provides further evidence that BMI is positively associated with cancer risk. In women from northern Sweden, up to 7% of all cancers were attributable to overweight and obesity and could be avoided by keeping BMI within the recommended range.

Independent effects of obesity and cortisol in predicting cardiovascular risk factors in men and women

Abstract. Walker BR, Soderberg S, Lindahl B, Olsson T (University of Edinburgh, Western General Hospital, Edinburgh, UK and the University of Umea, University Hospital, Umea, Sweden). Independent effects of obesity and cortisol in predicting cardiovascular risk factors in men and women. J Intern Med 2000; 247: 198–204.

Physical activity of subjects aged 50-64 years involved in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVE To describe physical activity of participants in the European Prospective Investigation into Cancer and Nutrition (EPIC). DESIGN A cross-sectional analysis of baseline data of a European prospective cohort study. SUBJECTS This analysis was restricted to participants in the age group 50-64 years, which was represented in all EPIC centres. It involved 236 386 participants from 25 centres in nine countries. In each EPIC centre, physical activity was assessed by standardised and validated questions. Frequency distribution of type of professional activity and participation in non-professional activities, and age-adjusted means, medians and percentiles of time dedicated to non-professional activities are presented for men and women from each centre. RESULTS Professional activity was most frequently classified as sedentary or standing in all centres. There was a wide variation regarding participation in different types of non-professional activities and time dedicated to these activities across EPIC centres. Over 80% of all EPIC participants engaged in walking, while less than 50% of the subjects participated in sport. Total time dedicated to recreational activities was highest among the Dutch participants and lowest among men from Malmö (Sweden) and women from Naples (Italy). In all centres, total time dedicated to recreational activity in the summer was higher than in the winter. Women from southern Europe spent the most time on housekeeping. CONCLUSIONS There is a considerable variation of physical activity across EPIC centres. This variation was especially evident for recreational activities in both men and women.

Burnout, working conditions and gender - results from the northern Sweden MONICA Study

BackgroundSick-leave because of mental and behavioural disorders has increased considerably in Sweden since the late nineties, and especially in women. The aim of this study was to assess the level of burnout in the general working population in northern Sweden and analyse its relation to working conditions and gender.MethodsIn this cross-sectional study the survey from the MONICA-study (Monitoring of Trends and Determinants in Cardiovascular Disease) in northern Sweden 2004 was used. A burnout instrument, the Shirom Melamed Burnout Questionnaire (SMBQ), was incorporated in the original survey which was sent to a random sample of 2500 individuals with a response rate of 76%. After including only actively working people, aged 25-64 years, our study population consisted of 1000 participants (497 women and 503 men). ANOVA and multiple linear regression models were used.ResultsThe prevalence of a high level of burnout (SMBQ >4.0) was 13%. Women had a higher level of burnout than men with the most pronounced difference in the age group 35-44 years. In both sexes the level of burnout decreased with age. Demand and control at work, and job insecurity were related to burnout. In women the level of education, socioeconomic position, work object, and working varying hours were of importance. Interaction effects were found between sex and work object, and sex and working hours. In a multiple regression analysis almost half of the gender difference could be explained by work related and life situational factors.ConclusionsWorking life conditions contributed to the level of burnout in this actively working sample from the general population in northern Sweden. Especially in women, socioeconomic position was associated with burnout. The high level of burnout in women compared to men was partly explained by more unfavourable working conditions and life situational factors. Efforts to level out gender differences in burnout should probably focus on improving both working and socioeconomic conditions for women.

No increase in the prevalence of known diabetes between 1986 and 1999 in subjects 25-64 years of age in northern Sweden.

Aims A global increase in diabetes is predicted due to higher body weight and less physical activity. Over the period 1986–1999, the body mass index (BMI) of the adult population of northern Sweden increased from 25.3 to 26.2 and the prevalence of obesity (BMI ≥ 30) from 11% to 15%, although this was more distal than central adiposity. Our hypothesis was that this would lead to a higher prevalence of diabetes.

Low serum insulin in traditional pacific islanders—The Kitava study

Increased serum insulin is related to abdominal obesity and high blood pressure in affluent societies where insulin, weight, and blood pressure typically increase with age. The increased insulin level has been thought to reflect insulin resistance, a well-known associated factor in the metabolic syndrome. In most nonwesternized populations, body weight and blood pressure do not increase with age and abdominal obesity is absent. However, it is not known whether serum insulin likewise does not increase with age in nonwesternized societies. Fasting levels of serum insulin were measured cross-sectionally in 164 subsistence horticulturalists aged 20 to 86 years in the tropical island of Kitava, Trobriand Islands, Papua New Guinea, and in 472 randomly selected Swedish controls aged 25 to 74 years from the Northern Sweden WHO Monitoring Trends and Determinants in Cardiovascular Diseases (MONICA) Study. In Kitava, the intake of Western food is negligible and stroke and ischemic heart disease are absent or rare. The body mass index (BMI) and diastolic blood pressure are low in Kitavans. The main outcome measures in this study were the means, distributions, and age relations of serum insulin in males and females of the two populations. Serum fasting insulin levels were lower in Kitava than in Sweden for all ages (P < .001). For example, the mean insulin concentration in 50- to 74-year-old Kitavans was only 50% of that in Swedish subjects. Furthermore, serum insulin decreased with age in Kitava, while it increased in Sweden in subjects over 50 years of age. Moreover, the age, BMI, and, in females, waist circumference predicted Kitavan insulin levels at age 50 to 74 years remarkably well when applied to multiple linear regression equations defined to predict the levels in Sweden. The low serum insulin that decreases with age in Kitavans adds to the evidence that a Western lifestyle is a primary cause of insulin resistance. Low serum insulin may partly explain the low prevalence of cardiovascular disease in Kitavans and probably relates to their marked leanness.

Improved fibrinolysis by intense lifestyle intervention. A randomized trial in subjects with impaired glucose tolerance

Objective. To assess the effects of lifestyle intervention on cardiovascular risk factors in general and especially on fibrinolysis.

Insulin resistance is inversely related to prostate cancer : a prospective study in Northern Sweden

Factors related to insulin resistance have been implicated in prostate cancer development, however, few analytical studies support such an association. We performed a case control study on 392 prostate cancer cases and 392 matched controls nested in a prospective cohort in Northern Sweden. Plasma concentrations of C‐peptide, leptin, glycated haemoglobin (HbA1c) and fasting and post‐load glucose were analysed and homeostatic model assessment of insulin resistance (HOMA‐IR) was calculated. Conditional logistic regression analyses were used to calculate odds ratios (OR) of prostate cancer. High levels of C‐peptide, HOMA‐IR, leptin and HbA1c were associated with significant decreases in risk of prostate cancer, with ORs for top vs. bottom quartile for C‐peptide of 0.59 (95% Confidence Interval [CI], 0.40–0.89; ptrend = 0.008), HOMA‐IR 0.60 (95% CI, 0.38–0.94; ptrend = 0.03), leptin 0.55 (95% CI, 0.36–0.84; ptrend = 0.006) and HbA1c 0.56 (95% CI, 0.35–0.91; ptrend = 0.02). All studied factors were strongly inversely related to risk among men less than 59 years of age at blood sampling, but not among older men, with a significant heterogeneity between the groups for leptin (pheterogeneity = 0.006) and fasting glucose (pheterogeneity = 0.03). C‐peptide and HOMA‐IR were strongly inversely related to non‐aggressive cancer but were non‐significantly positively related to risk of aggressive disease (pheterogeneity = 0.007 and 0.01, respectively). Our data suggest that androgens, which are inversely associated with insulin resistance, are important in the early prostate cancer development, whereas insulin resistance related factors may be important for tumour progression.