Physical activity improves the metabolic risk profiles in men and women: the Tromsø Study.

BACKGROUND: Because physical activity may affect risk of certain chronic diseases, we wanted to examine the effects of leisure time physical activity on the metabolic profiles. METHODS: In a population-based cohort study, 5220 men and 5869 women, aged 20 to 49 years at entry, took part in 2 surveys (1979-1980 and 1986-1987) with repeated assessments of self-reported leisure time activity. Measurements of body mass index (measured as the weight in kilograms divided by the square of the height in meters [BMI]) and levels of serum triglyceride, total cholesterol (total C), and high-density lipoprotein cholesterol (HDL-C) were studied in relation to 4 levels of physical activity. RESULTS: There was a dose-response relationship between serum lipid levels and BMI, and levels of physical activity in both sexes after adjustments for potential confounders. Differences in BMI and serum lipid levels between sedentary and sustained exercising groups were consistently more pronounced after 7 years than at baseline, especially in the oldest age group. Men reporting sustained very hard exercising compared with sedentary men had lower total C concentrations (5.65 mmol/L vs 6.21 mmol/L [218 mg/dL vs 240 mg/dL]), triglyceride levels (1.34 mmol/L vs 1.85 mmol/L [118 mg/dL vs 164 mg/dL] ), total C/HDL-C ratios by 19.0%, and BMI (23.9 kg/m2 vs 25.7 kg/m2), and higher HDL-C levels (1.52 mmol/L vs 1.36 mmol/L [59 mg/dL vs 52 mg/dL]). The combined sustained hard and very hard exercising group of women compared with sedentary women had lower total C concentrations (5.70 mmol/L vs 5.90 mmol/L [220 mg/ dL vs 228 mg/dL]), triglyceride levels (1.03 mmol/L vs 1.18 mmol/L [91 mg/dL vs 104 mg/dL]), total C/HDL-C ratios by 7.5%, BMI (23.1 kg/m2 vs 23.6 kg/m2), and higher HDL-C levels (1.73 mmol/L vs 1.66 mmol/L [67 mg/dL vs 64 mg/ dL]). An increase in leisure time activity over the 7 years improved metabolic profiles, whereas a decrease worsened them in both sexes. CONCLUSIONS: Sustained high levels and change from sedentary to higher levels of physical activity relative to sedentary men and women improved the metabolic risk profiles in both sexes. The differences observed are sufficiently large to have a beneficial effect in the prevention of certain chronic diseases.

A longitudinal study of the biological variability of plasma lipoproteins in healthy young adults.

The fasting serum concentrations of total cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), total triglyceride and apoprotein A1 were measured at intervals of 12-18 weeks for 60 weeks in 17 male and 11 female healthy young adults in order to assess the variability of these risk factors for coronary disease. No statistically significant seasonal changes were detected in any variable in either sex, although a progressive rise in apoprotein A1 concentration was observed. The coefficients of variation for random fluctuations with time were in the rank order: total cholesterol less than HDL-C less than apoprotein A1 less than LDL-C less than triglyceride. These differences were attributable to biological, rather than to methodological, factors. Within subjects, HDL cholesterol concentration varied inversely with triglyceride concentration and directly with apoprotein A1 concentration. The marked differences which exist in the biological variability of lipid risk factors for atherosclerosis need to be taken into account when making comparisons in epidemiological studies of the predictive powers of single on-entry measurements for future disease. Fluctuations of HDL-C with time appear to be related in part to variations in triglyceride-rich lipoprotein metabolism.

Serum total homocysteine and coronary heart disease.

BACKGROUND: Several studies have observed high plasma levels of homocysteine among patients with coronary heart disease (CHD). The only prospective study was based on US physicians, and concluded that homocysteine was associated with subsequent myocardial infarction (MI). However, the association was limited to those above a threshold level of homocysteine. METHODS: We conducted a nested case-control study among the 21,826 subjects, aged 12-61 years, who were surveyed in the municipality of Tromsø, Norway. Among those free from MI at the screening, 123 later developed CHD. Four controls were selected for each case. RESULTS: Level of homocysteine was higher in cases than in controls (12.7 +/- 4.7 versus 11.3 +/- 3.7 mumol/l (mean +/- SD); P = 0.002). The relative risk for a 4 mumol/l increase in serum homocysteine was 1.41 (95% confidence interval (CI): 1.16-1.71). Adjusting for possible confounders reduced the relative risk to 1.32 (95% CI: 1.05-1.65). There was no threshold level above which serum homocysteine is associated with CHD events. CONCLUSIONS: In the general population serum total homocysteine is an independent risk factor for CHD with no threshold level.

Distribution of high-density lipoprotein cholesterol according to age, sex, and ethnic origin: cardiovascular disease study in Finnmark 1977.

As a part of a survey for cardiovascular risk factors high-density lipoprotein cholesterol (HDL-C) was determined in 15 942 men and women aged 20-53. Women had on average 0.24 mmol/l higher HDL-C concentration than men. The difference was of the same magnitude at all ages. For both sexes HDL-C increased with age. The increase was partly influenced by other variables affecting the HDL-C concentration. After adjusting for the effect of height, weight, cigarette-smoking, physical activity in leisure time, and ethnic origin the age-related change was more pronounced, 0.13 mmol/l and 0.16 mmol/l difference between the youngest and the oldest age group for men and women respectively. The population comprised three ethnic groups. HDL-C did not differ among the women of different ethnic origin, but among men those of Lappish origin had higher HDL-C concentrations than the other groups. This difference was reduced after adjusting for other variables and was probably due more to external factors influencing the HDL-C concentration than specific ethnic-genetic traits.

Aetiology of peptic ulcer: a prospective population study in Norway.

STUDY OBJECTIVE: To analyse simultaneously the effect of several risk factors for peptic ulcer. DESIGN: Cohort study where all patients with new or incident peptic ulcers in a well defined population were registered for a seven year period. The follow up started with a comprehensive health survey including a questionnaire on diet, lifestyle, psychological and social conditions, and health. Relative risks, both sex specific and separate, for gastric and duodenal ulcers were estimated from proportional hazard regression analysis. SETTING: A population based survey conducted in the municipality of Tromsø, northern Norway. PARTICIPANTS: In 1980, a total of 21,440 men and women, aged 20 to 54 years and 20 to 49 years respectively, were invited to participate. A total of 14,667 people attended and returned the questionnaire. MAIN RESULTS: A total of 328 people had their first peptic ulcer in the follow up period. Age, cigarette smoking, first degree relatives with peptic ulcer, and low educational level were shared risk factors for peptic ulcer in both men and women. In men, frequent upper respiratory infections increased the risk of gastric ulcer and drinking a great deal of milk increased the risk of duodenal ulcer. None of the other dietary variables, including coffee and alcohol consumption, contributed significantly to the risk. Use of analgesics was not a risk factor, and none of the psychological indicators analysed carried any significant risk. CONCLUSIONS: Age, inheritance, and cigarette smoking are all important risk factors for peptic ulcer. The increased risk associated with low educational background indicate that social strains, comprising lifestyle and diet habits, are part of the multifactorial aetiology of peptic ulcer. No support was found for the assumption that peptic ulcer disease is a psychosomatic disorder. This study did not support the view that duodenal and gastric ulcers have different aetiologies-rather it showed a similarity in risk patterns.

Do general practitioner hospitals reduce the utilisation of general hospital beds? Evidence from Finnmark county in north Norway.

STUDY OBJECTIVE: To assess whether populations with access to general practitioner hospitals (GP hospitals) utilise general hospitals less than populations without such access. DESIGN: Observational study comparing the total rates of admissions and of occupied bed days in general hospitals between populations with and without access to GP hospitals. Comparisons were also made separately for diagnoses commonly encountered in GP hospitals. SETTING: Two general hospitals serving the population of Finnmark county in north Norway. PATIENTS: 35,435 admissions based on five years' routine recordings from the two hospitals. MAIN RESULTS: The total rate of admission to general hospitals was lower in peripheral municipalities with a GP hospital than in central municipalities without this kind of institution, 26% and 28% lower for men and women respectively. The corresponding differences were 38% and 52%, when analysed for occupied bed days. The differences were most pronounced for patients with respiratory diseases, cardiac failure, and cancer who are primarily or intermediately treated or cared for in GP hospitals, and for patients with stroke and fractures, who are regularly transferred from general hospitals to GP hospitals for longer term follow up care. CONCLUSION: GP hospitals seem to reduce the utilisation of general hospitals with respect to admissions as well as occupied bed days.

Changing incidence of peptic ulcer--facts or artefacts? A cohort study from Tromsø.

STUDY OBJECTIVE: The aim was to estimate the age and sex specific incidences of duodenal and gastric ulcers censored for death and migration. DESIGN: A population based cohort was followed seven years through records of x ray examinations, endoscopies, and operations in the only hospital serving the area. SETTING: The study was conducted in the municipality of Tromsø, Northern Norway, where all men aged 20 to 54 years and women aged 20 to 49 years in 1980, a total of 21,440, were included. MAIN RESULTS: We found an incidence of 1.47 (95% CI 1.21-1.76) and 0.88 (0.67-1.14) per 1000 person-years for gastric and 1.98 (1.69-2.31) and 0.85 (0.64-1.11) for duodenal ulcers in men and women, respectively. A small and insignificant sex difference for gastric ulcer was noted. The duodenal preponderance in men was only recognised among the ulcers identified by x ray, not among ulcers diagnosed by endoscopy. CONCLUSIONS: This population based study has, in contrast to recent studies from other areas, revealed an unchanged high incidence of gastric and duodenal ulcer in both sexes. Compared to earlier studies from this area it indicates a preponderance of duodenal ulcers. The study also shows the impact of attendance rate, death, and migration, and of diagnostic methods on the incidence estimates. Ignoring these potential biases may lead to conclusions on peptic ulcer trends that reflect artefacts rather than real changes in peptic ulcer occurrence.

Serum lipids and glucose concentrations in subjects using antihypertensive drugs: Finnmark 1977.

As a side project to a study of coronary risk factors 4878 men and women aged 20-53 were interviewed about present and previous use of antihypertensive drugs. Serum lipid and glucose concentrations were compared in 124 present users, 73 previous users, and 124 controls matched for age, sex, and systolic and diastolic blood pressure. Users of betablockers, thiazides, and other antihypertensive drugs had higher total cholesterol, triglycerides, and glucose and lower HDL-cholesterol than the other groups, but only the difference in HDL-cholesterol was statistically significant. Smokers had statistically significant lower HDL-cholesterol than non-smokers in drug users, whereas there were only minor differences between them in previous and never users. This indicates an interaction between smoking and current antihypertensive medication. The unfavourable serum lipid pattern may, if caused by drug use, explain the lack of influence that antihypertensive treatment has had on the incidence of coronary heart disease in intervention studies.

Is imposing risk awareness cultural imperialism?

Epidemiology is the main supplier of "bases of action" for preventive medicine and health promotion. Epidemiology and epidemiologists therefore have a responsibility not only for the quality and soundness of the risk estimates they deliver and for the way they are interpreted and used, but also for their consequences. In the industrialised world, the value of, and fascination with health is greater than ever, and the revelation from epidemiological research of new hazards and risks, conveyed to the public by the media, has become almost an every-day phenomenon. This "risk epidemic" in the modern media is paralleled in professional medical journals. It is in general endorsed by health promoters as a necessary foundation for increased health awareness and a desirable impetus for people to take responsibility for their own health through behavioural changes. Epidemiologists and health promoters, however, have in general not taken the possible side effects of increased risk awareness seriously enough. By increasing anxiety regarding disease, accidents and other adverse events, the risk epidemic enhances both health care dependence and health care consumption. More profoundly, and perhaps even more seriously, it changes the way people think about health, disease and death--and ultimately and at least potentially, their perspective on life more generally. The message from the odds ratios from epidemiological research advocates a rationalistic, individualistic, prospective life perspective where maximising control and minimising uncertainty is seen as a superior goal. The inconsistency between applying an expanded health concept, comprising elements of coping, self-realisation and psycho-physical functioning, and imposing intolerance to risk and uncertainty, is regularly overlooked. Acceptance and tolerance of risk and uncertainty, which are inherent elements of human life, is a prerequisite for coping and self-realisation. A further shift away from traditional working-class values like sociability, sharing, conviviality and tolerance can not be imposed without unwanted side effects on culture and human interaction. The moral and coercive crusade for increased risk awareness and purity in life style can too readily take on the form of cultural imperialism towards conformity. Epidemiologists and the health care movement in general have a mandate to fight disease and premature death; they have no explicit mandate to change culture.

The Tromsø Study: predictors of self-evaluated health--has society adopted the expanded health concept?

The determinants of self-evaluated general health status were examined in a comprehensive population study of 9408 men aged 20-61 and 9152 women aged 20-56. Reduced self-evaluated health was in both sexes closely related to symptoms and diseases connected to the musculo-skeletal system and psycho-social problems and less to age and some of the major chronic diseases. Physical activity at leisure time and workload were positively associated with self-evaluated health. Our findings indicate that an important dimension reflected by self-evaluation of health is the individual's perception of own physical performance and suffice in general. There is a striking gap between the conditions which reduce the population's subjective perceived health and our ability to offer these conditions effective treatment through the health care system. This suggests differences in health concept between the medical society and the population. The association between our applied measure and coronary risk profile, based on serum cholesterol, blood pressure and cigarette smoking, was found to be almost non-existent. This supports previous findings of self-evaluation of health as an independent predictor of survival.

Determinants and dimensions involved in self-evaluation of health.

This study explores mechanisms involved in self-evaluation of health by making specifications of linkages among various dimensions of health status, physiological measures, social and behavioral factors or characteristics. The proposed structural equation model is tested by using data from a comprehensive health survey of the population of Finnmark county, Norway (1987-88), including 4549 men and 4360 women aged 30-62. The findings suggest the burden of physical distress and reliance on permanent disablement benefit to play the key role in reducing self-evaluated health. The seemingly strong labelling impact of permanent work disability, contrasted the modest effect of diagnoses of chronic disease. Moreover, the impact of both these key factors and other important determinants is strongly socially patterned. Positive health related life-style appeared to have a positive impact on self-rated health, while preoccupation with health had a negative impact. This finding adds some credibility to the suggestion that the growing occupation and fascination with health have some negative health outcomes.

Medical specialists' choice of location: the role of geographical attachment in Norway.

The relation between current place of work (area of the country) and factors that might possibly represent doctors geographical attachments was studied in a sample of 322 Norwegian medical specialists. Location of hospital residency, age and geographical origin of spouse were associated with current location. Geographical attachment seems to influence doctors' locational choices from start of medical school until the end of their residency. The probability that a doctor shall locate in peripheral areas may increase from less than 10% to more than 50% if the doctor has the residency training in the periphery. Hence, favoring entrance to medical schools of students from the underserved areas, and location of graduate and postgraduate medical training in the underserved areas, as far as it is feasible while still maintaining medical standards, is suggested by the study.

Prevalences of endoscopic and histological findings in subjects with and without dyspepsia.

OBJECTIVE: To examine the association between dyspeptic symptoms and endoscopic and histological diagnoses. DESIGN: Cross sectional study of people with dyspepsia and controls matched for age and sex identified by questionnaire survey of all inhabitants aged 20 to 69. Endoscopy and histological examination was performed with the examiner blind to whether or not the patient had dyspepsia. SETTING: Population based survey in Sørreisa, Norway. SUBJECTS: All people with dyspepsia and age and sex matched people without dyspepsia were offered endoscopy. A total of 309 people with dyspepsia and 310 without dyspepsia underwent endoscopy, giving 273 matched pairs. MAIN OUTCOME MEASURES: Prevalences of endoscopic and histological diagnoses made according to internationally accepted standards. RESULTS: In all, 1802 of 2027 (88.9%) people returned the questionnaire. Of the 163 subjects who refused endoscopy, 114 were controls. Of five endoscopic and four histological diagnoses only peptic ulcer disease, endoscopic duodenitis, and active chronic gastritis were diagnosed significantly more often in people with dyspepsia. In all, 30% to 50% of the diagnoses of mucosal inflammation and peptic ulcer disease were made among subjects without dyspepsia, and only 10% of both those with and those without dyspepsia had normal endoscopic findings. CONCLUSIONS: The diagnostic findings, with possible exceptions of peptic ulcer disease and endoscopic duodenitis, showed no association of clinical value with dyspeptic symptoms. The small number of "normal" endoscopic findings in both those with and those without dyspepsia challenge well accepted endoscopic and histological diagnostic criteria with relation to the upper gastrointestinal tract.

Haemoglobin predicts total mortality in a general young and middle-aged male population. The Tromsø Study.

OBJECTIVE: The prognostic value of haemoglobin within normal references is seldom emphasized. The relationship between haemoglobin and mortality has been questioned because of the possible confounding of other risk factors. We investigated whether there was a curve linear relationship between haemoglobin and total mortality, and evaluated the possible modifying effects of smoking, body mass index, total cholesterol and systolic blood pressure. MATERIALS AND METHODS: In all, 6541 men aged between 20 and 49 years were examined in 1974 in a prospective, population-based study from the municipality of Tromsø, Northern Norway. During 20 years of follow-up (127 120 person-years), 495 deaths were identified. RESULTS: We found a U-shaped relationship between quintiles of haemoglobin and total mortality. Among the 35-49 years group, the multiple adjusted hazard ratios (95% CI) were 1.83 (1.31-2.57) in quintile 1 and 1.72 (1.23-2.41) in quintile 5, compared to quintile 3 of haemoglobin. Compared to the age-adjusted hazard ratios, the multiple adjustments tended to non-significantly enhance the association in the lowest quintiles and non-significantly attenuate the association in the highest quintiles. The relationship was most pronounced in smokers in a dose-response manner, but also present in non-smokers. CONCLUSIONS: High and low haemoglobin levels have an independent prognostic effect on mortality, although a possible effect of residual confounding cannot be ruled out. Smokers in quintile 1 and quintile 5 of haemoglobin were at increased risk of dying.

Seven-year longitudinal population study of change in gamma-glutamyltransferase: the Tromsø Study.

The determinants of individuals changes in gamma-glutamyltransferase (GGT) were examined in 1,171 males and 1,267 females in Tromsø, Norway, according to a 7-year longitudinal design. The basis for the study was two comprehensive population surveys in 1979-1980 and 1986-1987. In both sexes, increase in GGT displayed a strong association with increase in body mass index and hours fasting. In males, increase in GGT also showed a strong association with increase in frequency of inebriation and with decrease in physical activity. In females, increased systolic blood pressure, starting to use oral contraceptives, the occurrence of menopause, and decrease in consumption of boiled coffee were associated with increase in enzyme levels. The strengths of the associations were considerably greater in this longitudinal design compared with earlier cross-sectional studies.

The cardiovascular study in Finnmark county: coronary risk factors and the occurrence of myocardial infarction in first degree relatives and in subjects of different ethnic origin.

As a part of a survey for coronary risk factors, family history of myocardial infarction (MI) was obtained in 4806 men and women aged 20--49 years. The two groups of subjects with (510) and without (3533) first degree relatives with MI showed only minor differences with respect to serum cholesterol, blood pressure, blood glucose, serum triglycerides, relative body weight and cigarette consumption. As long as no other mechanism for transmission of familial risk is revealed, the occurrence of MI among first degree relatives therefore must be considered as independent and important coronary risk factor. The material was also analyzed with regard to the three ethnic groups--Lapps, Finns and Norsemen--which comprise the study population. A discrepancy between risk factor level and MI incidence between these three groups was observed.

The Tromsø heart study. A multiple regression analysis of the relationship between coronary risk factors and some physical and social variables.

Univariate analysis of the cross-sectional data of the Tromsø Heart Study revealed group differences in the levels of blood pressure and serum lipids. In order to isolate the contribution from each of the physical and social variables which characterized these groups, a multiple variate analysis was carried out with serum triglycerides, serum cholesterol, systolic and diastolic blood pressure as dependent variables. Besides age, height and weight, seasonal variation contributed substantially to the explanation of the variance of the dependent variables. The influence of the social variables was somewhat reduced compared to the univariate analysis, though most of them did remain significant also in the multivariate analysis. The explained percentage of the total variance ranged from 13% for systolic blood pressure to 26% for serum cholesterol.

The Tromsø Study: the positive predictive value of gamma-glutamyltransferase and an alcohol questionnaire in the detection of early-stage risk drinkers.

Based on the measurement of gamma-glutamyltransferase and a questionnaire on frequency of alcohol intake, 338 early-stage risk drinkers were identified from more than 20,000 participants in a health survey programme. Two-thirds (225) of these subjects were questioned regarding their 'true' alcohol intake at the first consultation. Positive predictive values were calculated for true daily intake of 30 and 40 g alcohol d-1 for men (20 and 30 g alcohol d-1 for women) on the basis of gamma-glutamyltransferase activity and the response to a questionnaire. The positive predictive values for a risk intake of 30 g d-1 in men increased from 0.49 to 0.88, with increasing values for gamma-glutamyltransferase activity and increasing frequency of alcohol intake. The corresponding values for a risk intake of 40 g d-1 were 0.34-0.75. In women, increasing gamma-glutamyltransferase activity gave no increase in positive predictive values. The estimates for increasing frequency of alcohol intake were unreliable due to small numbers.

The Tromso heart study: risk factors for coronary heart disease related to the occurrence of myocardial infarction in first degree relatives.

In a population survey for risk factors associated with coronary heart disease among 6595 men aged 20-49 years of age, a family history of myocardial infarction (MI) was obtained by interview. A high degree of concurrence (78%) was found between the reported and confirmed diagnoses. Subjects who had evidence of a previous MI had a significantly higher frequency of first degree relatives with MI compared to healthy men of the same age. In subjects with first degree relatives of either sex suffering from MI before age 50, the mean serum cholesterol concentration was found to be slightly but not significantly elevated. However, when the relatives were females below age 50, the subjects had significantly elevated mean systolic blood pressure (0.05 greater than p greater than 0.01). The differences between subjects with a positive and negative family history of MI were surprisingly small. Correspondingly, there was no difference in the frequency of MI relatives in subjects belonging to the upper and lower quintiles of the serum cholesterol and blood pressure distribution. The slight elevations in serum cholesterol and blood pressure contribute only to a very small extent to the increased risk to subjects with a positive family history.