Risk factors associated with body mass index increase in men at 28 years follow-up.

BACKGROUND: Several studies have reported a general increase in body mass index (BMI). AIM: To identify factors influencing BMI changes at 28 years follow-up. DESIGN: Prospective screening study. METHODS: The cohort of the Oslo I study of 1972/73 had another screening in 2000 (Oslo II). We present data for these men, and men from Oslo I who participated in five similar studies during 1996-2001. In all, 7157 men aged 20-49 years at first screening attended two health screenings, and complete data were available for 7104. BMI change from 1972/73 to 2000 was the dependent variable in multiple regression analyses. RESULTS: The percentage with obesity (BMI > or = 30) increased overall from 2.5% to 13.5%. The overall mean (SD) BMI increased from 24.2 (2.6) kg/m2 to 26.2 (3.4) kg/m2. The increase was largest (3.9 (2.5) kg/m2) among men aged 20-24 in 1972/73 and least (1.6 (2.5) kg/m2) in those aged 45-49 years. No age trend was observed for those with BMI > or = 30.0 kg/m2 in 1972/3. On multiple regression analysis, increasing triglycerides, systolic blood pressure, age and non-fasting glucose, decreasing physical activity and not smoking were all significantly related to increasing BMI. Having stopped smoking was also related to increased BMI. Daily smoking in both 1972/73 and 2000, and daily smoking in 2000 but not in 1972/73, were inversely related to increased BMI. DISCUSSION: There was a substantial increase in BMI, with the largest increase in the younger men, except in those who were already obese at first screening. Overall, obesity increased by 11% in the study period and was associated with multiple life-style factors.

Age-specific genetic effects for blood pressure.

Correlations between relatives were determined for systolic and diastolic blood pressure. The correlations decrease as age differences between relatives increase in a Norwegian sample with 43,751 parent-offspring pairs, 19,140 pairs of siblings, and 169 pairs of twins. A simple biometric model specifying only age-specific genetic additive effects and environmental effects fitted well to correlations between cotwins, pairs of siblings, and parent-offspring dyads in subsets of relatives grouped by age differences. None of the environmental effects appeared to be due to environmental factors that are shared by family members. Models that excluded a parameter for the age-specific genetic influence did not fit the data. The results may partly explain what seems to be a discrepancy between relatively low parent-offspring correlations from previous nuclear family studies and high correlations from twin studies, especially in identical twins.

Serum glucose levels during long-term observation of treated and untreated men with mild hypertension. The Oslo study.

Serum glucose levels, triglyceride levels, and body weight are reported from a controlled drug trial in men, aged 40 to 49, with uncomplicated mild hypertension. The drug treatment started with hydrochlorothiazide alone, and methyldopa was added when necessary. If side effects occurred, methyldopa was replaced by propranolol. No detailed advice about diet, smoking, or weight reduction was given to any group. The untreated control subjects had a small increase in serum glucose levels during five years, from 6.08 to 6.21 mmol/liter. Those treated with hydrochlorothiazide alone and those treated with hydrochlorothiazide plus methyldopa had a small increase in serum glucose levels of the same order as that in the control subjects. However, those receiving the thiazide/propranolol combination experienced a sizeable increase in glucose levels, from 5.96 to 6.53 mmol/liter (p less than 0.001). This increase was significantly greater than the increase in the other groups (p less than 0.001). The thiazide/propranolol group also showed a significant increase in serum triglyceride levels (p less than 0.05). There was no difference in serum potassium levels in the different drug groups. The results indicate that moderate thiazide doses do not have significant effects on serum glucose levels in this age group. Propranolol in combination with thiazide seems to increase the level of serum glucose.

Is blood pressure treatment as effective in a population setting as in controlled trials? Results from a prospective study.

OBJECTIVE: To evaluate the effectiveness of treatment in situations in which general practitioners and patients use medication according to their own judgement, and where selection, compliance and follow-up varies. This prospective population study differs from the efficacy of treatment studied in randomized trials. DESIGN: Baseline (1974-1976) and repeat (1977-1981) cardiovascular screenings of all males aged 35-49 years in three counties in Norway, with mortality follow-up from the second screening until 1990. SETTING: A nationwide ambulatory screening service reporting community results and referring high-risk subjects to their local general practitioners. PARTICIPANTS: A total of 21,314 males (86%) attended both screenings, of whom 840 took blood pressure medication at the second screening. Males with cardiovascular disease, diabetes or blood pressure treatment at baseline were excluded. MAIN OUTCOME MEASURES: Changes in coronary risk factors, mortality from all causes, coronary heart disease and non-cardiovascular causes. RESULTS: The effect of treatment on blood pressure was small, and the attainment of reasonable target blood pressures was rare. The cholesterol level decreased and the level of triglycerides increased more in the treatment group than in the untreated group. Blood pressure treatment was associated with increased mortality in most risk strata, and at pretreatment systolic blood pressures up to 184 mmHg. A particularly high mortality rate was found when blood pressure increased despite treatment and at low pretreatment blood pressures. According to Cox proportional hazards analyses controlling for pretreatment blood pressure, cholesterol, age, smoking and body mass index, the relative risk of coronary heart disease death in the treatment group was 1.8 (95% confidence interval 1.3-2.6). CONCLUSION: The benefit experienced from the trials turned into an adverse effect of treatment in the population setting, particularly at low pretreatment blood pressure, and when blood pressure increased during treatment.

Experiences of the Janus Serum Bank in Norway.

The ongoing JANUS project was started in 1973. The serum bank comprises 424,938 serum samples consolidated from 293,692 donors. The specimens are stored at -25 degrees C. From 1 to 13 consecutive samples are available from each donor. Up to October 1993 about 14,000 of the donors had developed some form of cancer. Frozen serum samples collected from a few months to 19 years prior to clinical recognition of their disease are available for research purposes. The principle aim of the JANUS project is to search in the premorbid sera for chemical, biochemical, immunological or other changes that might be indicative of cancer development at early stages. Gas chromatography-mass spectrometry and two-dimensional protein electrophoresis have been used to evaluate the stability of the frozen sera. Some recent findings are: CA-125 may be elevated months prior to the diagnosis of ovarian cancer; serum thyroglobulin may be a preclinical tumor marker in subgroups of thyroid cancer; low levels of selenium in serum reflects increased risk of thyroid cancer; raised antibodies in serum against Epstein-Barr virus is a risk factor for development of Hodgkins disease; prostate-specific antigen may be elevated years prior to clinical diagnosis of prostate cancer; and linoleic acid in serum phospholipids is inversely related to breast cancer risk. The serum bank is, in principle, suitable for environmental studies, e.g., human exposure assessment. The steering committee of the JANUS project is open to suggestions for collaborative research on this topic.

Serum lipids in postmenopausal or perimenopausal women using estrogen alone, estrogen with levonorgestrel, or estrogen with norethisterone, compared with nonusers: results from a cross-sectional study in two Norwegian counties 1985-1988.

The aim of this study was to compare, in a population setting of postmenopausal or perimenopausal women aged 40 to 54, the levels of serum lipids in women using different hormone replacement therapy (HRT) regimens with women using no sex hormones. There was no unequivocal tendency of a more healthy lifestyle among those using HRT than among nonusers. Any type of regimen was associated with a lower mean level of total and calculated low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol was 0.08 mmol/L (5.2%) higher in those using estrogen alone, 0.07 mmol/L (4.5%) higher in users of HRT with norethisterone, and 0.07 mmol/L (4.5%) lower in users of HRT with levonorgestrel, compared with nonusers. The ratio of total-to-HDL cholesterol was lower by 0.37 (6.1%) in those using estrogen alone, by 0.65 (12.3%) in those using HRT with norethisterone, and by 0.24 (5.3%) in those using estrogen with levonorgestrel. There was no association between body mass index and HDL-cholesterol among women who used HRT with norethisterone, whereas an inverse relationship was present in those using estrogen alone and in nonusers (P [interaction] < 0.05).

Prediagnostic serum selenium in a case-control study of thyroid cancer.

Sera from 43 persons who developed thyroid cancer on an average 4.8 years after blood sampling were compared with sera from controls. Three controls per case matched for sex, age, place of residence and year of blood sampling, with regard to serum selenium and serum copper. Cases were significantly lower in serum selenium than controls, and the estimated odds ratio of thyroid cancer increased from 1 for levels greater than or equal to 1.65 mumol/l, to 6.1 for levels 1.26-1.64 mumol/l, to 7.7 for levels less than or equal to 1.25 mumol/l. When time from blood sampling to diagnosis of the case was considered, it could be shown that the protective effect of high serum selenium concentrations was restricted to the last (less than 7) years prior to the diagnosis of thyroid cancer. The serum selenium concentration of cases tended to decrease relative to controls the shorter time was from blood sampling to the diagnosis. There was no difference between cases and controls with regard to serum copper.

Four-year mortality by some socioeconomic indicators: the Oslo study.

The association between four-year mortality and some socioeconomic indicators has been studied in al Oslo men aged 40--49, invited to a screening programme for cardiovascular disease, and in a 'healthy' subgroup of participating men free of cardiovascular disease and diabetes at screening. The lowest social class exhibited a much higher total mortality than the other classes. This was pronounced for a variety of causes of death, such as cancer of the lung, accidents and homicide, and coronary heart disease. The negative mortality gradient by increasing socioeconomic status can to a certain degree be 'explained' by the coronary risk factor pattern.

Asbestos-related radiographic changes by ILO classification of 10 x 10 cm chest X-rays in a screening of the general population.

A sample of 1388 10 x 10 cm chest X-rays from a previous population screening of males aged 40+ years were reevaluated by use of the ILO classification. There were 1036 films of subjects from an industrialized town, and 352 from a rural community. The observed rates of parenchymal changes (profusion > or = 1/0) at the reevaluation were 1.3% in the urban community and 3.4% in the rural community. The corresponding figures for pleural changes were 5.0% and 0.6%, respectively. Based on additional questionnaire information on asbestos exposure, it was found that the radiographic changes were probably related to past asbestos exposure for 2.3% of the subjects from the urban community and 0.6% from the rural community. In cases of asbestos-related illnesses the mean time since first exposure to asbestos was 35.9 years, whereas the mean duration of the exposures was 11.4 years. The results seem to indicate that the ILO reassessment of the radiographs was more sensitive in detecting pleural changes than the previous clinical screening of both small and large films.

Previous asbestos exposure and smoking habits in the county of Telemark, Norway--a cross-sectional population study.

A cross-sectional population study. Scand J Work Environ Health 12 (1986) 561-566. In order to study the number of persons previously exposed to asbestos in the general population, an investigation with a self-administered questionnaire and a screening with 10 X 10-cm chest radiographs was conducted among 28,216 men aged 40 years and over in nine municipalities in the county of Telemark, Norway. Among the 21,453 subjects who answered the questionnaire in the primary screening, 3,888 (18.1%) reported previous occupational exposure to asbestos. Of the exposed subjects 2,368 (61.4%) were less than 60 years of age, and 2,611 (69.9%) had been exposed for the first time after 1950. In regard to the degree of exposure, 77.7% considered their previous exposure to be light. Past and present smoking habits were recorded for all the subjects, and a high-risk group of 1,734 subjects with past exposure to asbestos and present smoking was identified. Approximately 270 incident cases of lung cancer can be expected among the 21,453 study subjects during the next 10 years, and it is estimated that about 110 of these cases will occur in the high-risk group with combined asbestos-cigarette exposure.

Asbestos-related findings in chest radiographs of the male population of the county of Telemark, Norway--a cross-sectional study.

In order to investigate the prevalence of asbestos-related diseases, a cross-sectional population study was conducted among 28,216 men aged 40 years in nine municipalities of the county of Telemark, Norway. In a primary radiographic screening 10 X 10-cm chest radiographs were taken of 21,483 persons. In two independent readings of the radiographs, pleural changes were observed in 6.9 and 8.5% of the study subjects. Radiographic findings in the primary screening led to 1,431 subjects being selected for a reexamination. On the basis of occupational histories and 40 X 40-cm chest radiographs, it was concluded that 470 of these subjects (2.2% of the screened population) had radiographic changes consistent with an asbestos-related disorder. Among these, 86 had lung fibrosis (82 in combination with pleural plaques) and 384 had pleural plaques only. There were marked differences in the occurrence of asbestos-related disorders between the seven urban and two rural communities studied, and agreement was observed between the occurrence of such disorders and the degree and duration of the reported asbestos exposure. The study presents evidence that asbestos-related disorders may be more prevalent in the general male population than has been recognized earlier.

The JANUS serum bank.

The on-going JANUS project was initiated by the Norwegian Cancer Society in 1973. The serum bank comprises close to 0.5 million serum samples collected from 170,000 donors. From 2-16 consecutive samples are available from each donor. The sera are stored at -25 degrees C. At regular intervals the JANUS-collection is matched against the files of the Norwegian Cancer Registry. From 1973 to 1991 almost 5000 of the donors have developed some form of cancer. Frozen serum samples collected from a few months to 18 years prior to clinical recognition of their disease are consequently available for research purposes. The aim of the JANUS-project is to search in these premorbid sera for chemical, biochemical, immunological or other changes that might be indicative of cancer development at early stages. Gas chromatography-mass spectrometry and two-dimensional protein electrophoresis have been used to evaluate the stability of the frozen sera. Some recent findings are: CA125 is elevated several months prior to diagnosis of ovarian cancer; serum thyroglobulin may be a preclinical tumour marker in subgroups of thyroid cancer; low level of selenium in serum reflects increased risk of thyroid cancer; and raised antibodies in serum against Epstein-Barr virus is a risk factor for development of Hodgkin's disease. On-going research includes trace elements and cancer, and studies on lipid-profiles, diet and cancer. The serum bank may in principle be used for other purposes, e.g. in environmental studies. Analysis of sequential sera may determine chemical substances in the sera that might reflect differences in exposure to environmental pollutants in the period 1973-1991.

Coffee consumption and death from coronary heart disease in middle aged Norwegian men and women.

OBJECTIVE: To study the association between number of cups of coffee consumed per day and coronary death when taking other major coronary risk factors into account. DESIGN: Men and women attending screening and followed up for a mean of 6.4 years. SETTING: Cardiovascular survey performed by ambulatory teams from the National Health Screening Service in Norway. PARTICIPANTS: All middle aged people in three counties: 19,398 men and 19,166 women aged 35-54 years who reported neither cardiovascular disease or diabetes nor symptoms of angina pectoris or intermittent claudication. MAIN OUTCOME MEASURE: Predictive value of number of cups of coffee consumed per day. RESULTS: At initial screening total serum cholesterol concentration, high density lipoprotein cholesterol concentration, blood pressure, height, and weight were measured and self reported information about smoking history, physical activity, and coffee drinking habits was recorded. Altogether 168 men and 16 women died of coronary heart disease during follow up. Mean cholesterol concentrations for men and women were almost identical and increased from the lowest to highest coffee consumption group (13.1% and 10.9% respectively). With the proportional hazards model and adjustment for age, total serum and high density lipoprotein cholesterol concentrations, systolic blood pressure, and number of cigarettes per day the coefficient for coffee corresponded to a relative risk between nine or more cups of coffee and less than one cup of 2.2 (95% confidence interval 1.1 to 4.5) for men and 5.1 (0.4 to 60.3) for women. For men the relative risk varied among the three counties. CONCLUSIONS: Coffee may affect mortality from coronary heart disease over and above its effect in raising cholesterol concentrations.

Treatment of hypertension as a risk factor in a prospective study.

The association between blood pressure treatment, blood pressure level and mortality, taking other cardiovascular risk factors into account was studied. A 12-year follow-up of a cardiovascular risk factor screening performed by the Oslo study group in Oslo and by ambulatory teams from the National Health Screening Survey in three counties in Norway was done. All men in Oslo and all men and women in the three counties, (age 40-49) participated, of these 33154 men and 16407 women have complete data on blood pressure and treatment, including subjects reporting previous myocardial infarction or stroke. Mortality from coronary heart disease, stroke and all causes by blood pressure treatment and blood pressure level were studied. At the initial screening 1058 men and 817 women reported taking blood pressure medication, of which 201 and 41 died during follow-up. Total number of deaths were 2341 in men and 421 in women, of these 131 deaths in men and 47 in women reporting previous infarction or stroke. Those reporting blood pressure treatment had a marked excess mortality from cardiovascular disease and all causes of death. A J-shaped association between blood pressure and mortality was marked in the treated group, but weak in those not on treatment. It is concluded that blood pressure treatment is associated with excess mortality from all causes. This may indicate that "real life" treatment outcomes are inferior to those reported from controlled clinical trials. There is a J-shaped association between all cause mortality and blood pressure in men on treatment.

Changes in smoking habits and body weight after a three-year period--the cardiovascular disease study in Finnmark.

Smoking habits and body weight were registered on two occasions 3 yr apart in the county of Finnmark in 12,329 persons aged 20-49 yr. Among quitters, there was a mean weight increase of 2.7 kg for females and 3.6 kg for males; while among starters, there was a mean weight decrease of 0.9 for females and 2.5 for males. Mean weight continued to increase for at least up to 1 yr after quitting. A dose-response relationship was established between number of cigarettes smoked prior to quitting and weight gain. Females starting to smoke cigarettes reduced weight in proportion to daily cigarette consumption. There were no changes of clinical significance in main cardiovascular diseases risk factors with changes in cigarette consumption (and weight).

Sex differences in risk factors for clinical diabetes mellitus in a general population: a 12-year follow-up of the Finnmark Study.

The associations among obesity, height, cardiovascular risk factors, and the incidence of clinical diabetes mellitus were investigated in the Norwegian population-based Finnmark Study of 11,654 men and women aged 35-52 years at baseline in 1977-1978. A total of 87 cases of diabetes among men and 75 cases among women were registered during 12 years of follow-up. The incidence of diabetes was 1.1 per 1,000 person-years in women and 1.2 per 1,000 person-years in men, but sex-related differences in risk factors were noted. Body mass index was the dominant risk factor in men and predicted diabetes in a dose-response relation in both sexes. However, in women, the association between body mass index and diabetes was greatly attenuated after multivariable adjustment. Serum lipid concentrations were similar in prediabetic men and women; thus, prediabetic women had a relatively more adverse metabolic risk profile as compared with nondiabetics of the same sex. In multivariable analysis, high density lipoprotein cholesterol was inversely related to diabetes in women (relative risk per 0.3 mmol/liter, 0.53; 95% confidence interval 0.41-0.70) but not in men (relative risk, 0.97; 95% confidence interval 0.78-1.19). Serum glucose was a highly significant predictor in both sexes, while height was inversely related to diabetes only in women (relative risk per 5 cm, 0.71; 95% confidence interval 0.58-0.87).

[Is blood pressure treatment as effective in a population setting as in controlled studies?]. / Er blodtrykksbehandling like effektivt i befolkningen som i kontrollerte forsøk?

Baseline (1974-76) and repeat (1977-81) cardiovascular screenings of 21,314 men aged 35-49 years brought to light 840 men who had started treatment between screenings. These were compared with men who had remained untreated. The effects of treatment on blood pressure were small, and normal target blood pressures rare. At pretreatment blood pressure up to systolic 184 mm Hg, and in most risk strata, both total mortality and cardiovascular mortality were higher among the men on treatment. This study shows an adverse effect of treatment in a population setting, particularly at low pretreatment blood pressure, and if blood pressure increases upon treatment.

Smoking, serum lipids, blood pressure, and sex differences in myocardial infarction. A 12-year follow-up of the Finnmark Study.

BACKGROUND: Few epidemiological studies have investigated the relative importance of major coronary risk factors in the two sexes within the same study population. In particular, it is not clear whether smoking carries a similar risk of coronary heart disease in men and women. METHODS AND RESULTS: The associations between smoking, serum lipids, blood pressure, and myocardial infarction were examined in a population-based prospective study of 11,843 men and women aged 35 to 52 years at entry. During 12 years, 495 cases of first myocardial infarction among men and 103 cases among women were identified. Myocardial infarction incidence was 4.6 times higher among men. The incidence was increased sixfold in women and threefold in men who smoked at least 20 cigarettes per day compared with never-smokers, and the rate in female heavy smokers exceeded that of never-smoking men. Multivariate analysis identified current smoking as a stronger risk factor in women (relative risk, 3.3; 95% confidence interval [CI], 2.1 to 5.1) than in men (relative risk, 1.9; 95% CI, 1.6 to 2.3). Among those under 45 years old at entry, the smoking-related sex difference was more pronounced (in women: relative risk, 7.1; 95% CI, 2.6 to 19.1) (in men: relative risk, 2.3; 95% CI, 1.6 to 3.2). Serum total cholesterol, HDL cholesterol, and systolic blood pressure were also highly significant predictors in both sexes. CONCLUSIONS: Smoking was a stronger risk factor for myocardial infarction in middle-aged women than in men. Relative risks associated with serum lipids and blood pressure were similar despite large sex differences in myocardial infarction incidence rates.

Body height, cardiovascular risk factors, and risk of stroke in middle-aged men and women. A 14-year follow-up of the Finnmark Study.

BACKGROUND: Geographical differences in stroke mortality are not fully explained by population variations in blood pressure and antihypertensive treatment. Some studies have suggested that factors connected with health and nutrition in early life may be related to stroke morbidity and mortality. Body height is a sensitive marker for socioeconomic conditions, but results are conflicting as to whether height is associated with stroke. METHODS AND RESULTS: In a population-based study, we investigated stroke incidence in relation to height and classic cardiovascular risk factors. A total of 13,266 men and women 35 to 52 years of age were followed for 14 years, and 241 first events of stroke were registered. Stroke incidence was 36% higher in men. Height was inversely related to stroke in a dose-response manner. Per 5-cm increase in height, the age-adjusted risk of stroke was 25% lower in women (P < .0001) and 18% lower in men (P = .0007). Systolic blood pressure and daily smoking were positively associated with stroke in both sexes, while serum triglyceride level was a significant risk factor in women only (relative risk per 1 mmol/L, 1.3; 95% CI, 1.1 to 1.5). The associations remained after adjustment for possible confounders and were also observed in certain subtypes of stroke. CONCLUSIONS: The results are consistent with the theory that factors influencing early growth as well as adult lifestyle factors contribute to cerebrovascular disease in adult age.