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N Hammar

Publications and source records attributed to N Hammar.

At least 55 records · Page 3Linked to original sources
PubMed1996

Myocardial infarction among male bus, taxi, and lorry drivers in middle Sweden.

OBJECTIVES: The aim of the present case-referent study was to investigate the incidence of myocardial infarction among male professional drivers, taking the type of vehicles and area of residence into account. METHODS: The study base comprised all men aged 30-74 in five counties in middle Sweden during 1976-81 or 1976-84. Incident cases of the first episode of myocardial infarction were identified from registers of hospital admissions and causes of deaths. Referents were selected randomly from the study base. Information about occupation was obtained from the national censuses in 1970 and 1975. The possible impact from tobacco smoking and overweight were evaluated by simulations in combination with indirect data on these factors. RESULTS: The incidence of myocardial infarction was increased among bus drivers in Stockholm (relative risk (RR) = 1.53, 95% confidence interval (95% CI) 1.15-2.05), and among taxi drivers both in Stockholm (RR 1.65, 95% CI 1.30-2.11) and in the surrounding rural counties (RR 1.82, 95% CI 1.17-2.82). A smaller increase was found among long distance lorry drivers, whereas the relative risk among short distance lorry drivers was close to unity. Indirect comparisons make it unlikely that the excess among bus drivers in Stockholm could be explained by uncontrolled confounding from tobacco smoking or overweight. A very high proportion (more than 80%) of urban bus drivers in Sweden report a combination of high psychological demands and low control at work. CONCLUSIONS: Different types of drivers are at different risk of myocardial infarction. Bus drivers in urban areas seem to be at an increased risk, which is unlikely to be explained by uncontrolled confounding from tobacco smoking or overweight. Psychosocial work conditions may play a part in the increased incidence of myocardial infarction among urban bus drivers and should be investigated further.

Adult↗
PubMed1994

Are geographical differences and time trends in myocardial infarction incidence in Sweden real? Validity of hospital discharge diagnoses.

In Sweden, acute myocardial infarction (AMI) incidence has been found to differ considerably between the neighboring counties of Stockholm and Gävleborg, with an increase in Stockholm during the 1970s. We estimated the AMI incidence in Stockholm in 1973 and in both areas in 1981. To determine if there were differences in the validity of hospital discharge diagnoses, random samples of AMI patients were examined for diagnostic criteria for AMI. In both genders, AMI incidence was higher in Gävleborg than in Stockholm (relative risk (RR) 1.34 for men and 1.21 for women) and increased in Stockholm from 1973 to 1981 (RR 1.21 for men and 1.29 for women). The proportion of patients fulfilling the diagnostic criteria for AMI was similar in both areas in 1981 but 10% less in Stockholm in 1981 than in 1973. These results suggest that differences in the validity of hospital discharge diagnoses cannot explain the geographical differences in AMI incidence, but that this may have contributed to the increasing incidence seen in Stockholm county.

Adult↗
PubMed1994

Job characteristics and the incidence of myocardial infarction.

In Sweden, there are large differences in the incidence of myocardial infarction (MI) among occupational groups. These differences may to some extent be due to work environment factors, including psychosocial job strain. The aim of the present study was to estimate the relative risk (RR) of MI for Swedish men and women in high strain occupations as compared to those in low strain occupations. The association between job strain and MI was studied by case-control methods. The study base comprised the population of four Swedish counties from 1976-1981 and of Stockholm county from 1976-1984. Incident cases of MI were identified through hospital discharges together with deaths. Information about occupation was obtained from the 1970 and the 1975 censuses and individuals were characterized with regard to job strain on the basis of their job title. In all, 9295 cases and 26 101 controls with unchanged type of occupation from 1970 to 1975 were included in the analyses. Men and women aged < 65 in high strain occupations showed an RR of 1.1-1.4, and men age < 55 an RR of 1.2-1.6 compared to those in low strain occupations. Similar results were obtained in analyses of male white and blue collar workers respectively. If the association between job strain and MI is causal this could be of great importance in explaining differences in MI incidence among occupational groups in Sweden.

Cross-Sectional Studies↗
PubMed1993

Incidence of myocardial infarction and mortality from specific causes among bus drivers in Sweden.

Previous studies have indicated that urban bus drivers have an increased risk of coronary heart disease. In the present investigation two separate studies were carried out. In the first study the mortality from myocardial infarction (MI), as well as from other causes for all male bus drivers in Sweden (9446), was investigated and compared to those of other employed men over a 15-year period. A 50% increase in mortality from MI was observed among drivers in Stockholm and Göteborg and Bohus counties, the two counties where the two largest cities in Sweden are situated. No increased mortality from lung cancer, any cancer (all sites combined), or from all causes combined was observed for these drivers. For bus drivers in the predominantly rural areas no excess mortality from MI, or any other cause, was observed. In the second study the incidence of MI among male bus drivers, as compared with other employed men, was studied in five Swedish counties by case referent methods. An increased incidence of first events of MI, (relative risk = 1.6, 95% confidence interval (CI) 1.1-1.9) was observed for bus drivers in Stockholm county. According to our results, urban bus drivers thus have an increased risk of developing MI. The findings also suggest that factors in the work environment of urban bus drivers may contribute to this increased risk. Factors of possible importance are job strain, irregular working hours, a sedentary job, automobile exhaust fumes, and noise.

Automobile Driving↗
PubMed1992

Time trends in survival from myocardial infarction in Stockholm County 1976-1984.

In Stockholm county, a rapid decline in mortality from acute myocardial infarction (AMI) was observed among middle-aged men in the early 1980s. In the present study survival among AMI patients from 1976 to 1984 was investigated in order to explore whether improvements in survival may have contributed to this decline. AMI patients aged 30-74 years (n = 16,108) were identified through a hospital discharge register. Deaths within one year of hospital admission were ascertained by means of linkage to the national cause of death register. Survival 1 year after hospital admission increased in both genders during the period 1981-1984, but among women there was no uniform trend over the whole study period. The estimated age-adjusted relative risk of death within one year after hospital admission for patients with a first infarction admitted to hospital in 1983-1984 as compared to in 1981-1982 was 0.88 for men and 0.79 for women. The causes of the observed increase in survival could not be determined from this study, but changes in medical intervention as well as diagnostic improvements may have been important. Improved survival may have contributed to about 30% of the decline in mortality from AMI among middle-aged men in Stockholm county during the early 1980s.

Adult↗
PubMed1992

Geographical differences in myocardial infarction incidence in eight Swedish counties, 1976-1981.

Considerable regional variation in coronary heart disease mortality has been observed in Sweden. This variation is of public health concern and is also a point of departure for etiologic studies. The central aim of the present study was to investigate whether there are also regional differences in myocardial infarction incidence and to evaluate whether these are likely to be explained by regional differences in smoking, blood pressure, and serum cholesterol. The study base consisted of subjects age 30-64 living in eight Swedish counties during 1976-1981. Cases of myocardial infarction were identified using both hospital discharge and death records. A 30-40% increased incidence of myocardial infarction was found in the two northernmost counties compared with Stockholm county. The regional differences in myocardial infarction incidence were not related to differences in smoking but might be due in part to differences in serum cholesterol and blood pressure, and to socioeconomic factors as well.

Adult↗
PubMed1992

Differences in the incidence of myocardial infarction among occupational groups.

An inverse relationship between social class and coronary heart disease has been observed in several countries, but few studies have investigated the incidence of this disease over different occupational groups. A case-referent study was carried out to estimate the relative risk of a first myocardial infarction in various occupational groups. Cases of myocardial infarction (N = 36,602) were identified from both hospital discharge and death records. Two referents for each case were randomly selected from the study base. Information about occupation was obtained from two consecutive censuses. An increased incidence, compared with that of others employed, was found for persons in some occupations in production work, transport work (men), and service work (women). Low relative risk were found mainly for persons in occupations demanding a high education. The relative risks ranged from 0.3 to 2.8. Several factors, occupational as well as nonoccupational, may be of importance in explaining the findings.

Adult↗
PubMed1991

Identification of cases of myocardial infarction: hospital discharge data and mortality data compared to myocardial infarction community registers.

Identification of incident myocardial infarction (MI) cases in a defined population using hospital discharge data and mortality data in combination has been suggested. This method of case identification was compared to that of use of MI community registers set up in accordance with principles adopted in a World Health Organization collaborative programme. The comparison comprised data for four Swedish cities over a number of years. On average 81% of incident hospital-treated cases below 65 years of age identified through MI community registers were found by the retrospective use of the method based on hospital discharge data and mortality data. Of hospital-treated cases identified by the latter method, 83% were also found by the MI community registers. For cases fulfilling the diagnostic criteria employed by the MI community registers this proportion would be higher, probably 87%-92%. Several reasons for cases being missed by either method were suggested by the results. According to the findings of this study, the case identification of the method based on hospital discharge data and mortality data seems to be somewhat less efficient compared to use of MI community registers. This may be of importance in descriptive epidemiological studies, but is of less significance in analytical studies. The relative efficiency of the former method could be improved by a more reliable system for the recording of hospital discharges. If supplemented by a validation procedure, it could yield sufficiently accurate data for many epidemiological applications at a fairly low cost.

Acute Disease↗
PubMed1991

Retrospective versus original information on diet among cases of colorectal cancer and controls.

A cohort of subjects born 1908 to 1925 answered a questionnaire on dietary habits in 1967 (original information). Of the cases of colorectal cancer that were diagnosed in this cohort 1968-1983, 50 were still alive in 1987. A total of 150 controls were selected as a stratified (age, sex) random sample of those who did not have a colorectal cancer. In 1987, the cases and controls were asked to fill in a questionnaire on dietary habits in 1967 (retrospective information) as well as on their current dietary habits. The questions were identical and used to compare retrospective and original information on diet among cases and controls, taking into account any changes in dietary habits during the intervening period. Cases and controls usually had a similar tendency to overestimate or underestimate their previous food intake. For both cases and controls, the tendency to overestimate previous intake was closely related to an increase in consumption during the intervening period and vice versa. Among those subjects who had not altered their consumption during the intervening period, there was usually a rather good agreement between the retrospective and original information. This was true for the cases as well as for the controls. For certain food items, the results suggest that the use of retrospective information would introduce a differential misclassification. In order to avoid or reduce a differential misclassification introduced by differences between cases and controls in changes in consumption due to the disease under study, it may be advisable to interview the cases as soon as possible after diagnosis or even at the time of preliminary diagnosis.

Aged↗
PubMed1986

Respiratory symptoms and annoyance in the vicinity of coal-fired plants.

This study constitutes one part of a program for assessing the impact of coal-fired power plants on the surrounding communities. A questionnaire was mailed to a total of 12,000 subjects living in six areas with coal-fired plants and in matched reference areas. The participation rate was 77.3%. In one coal-fired plant/reference area pair, a more detailed medical examination was carried out among subjects who reported symptoms of the respiratory tract. The match between coal-fired plant and reference areas was successful primarily in three pairs. Neither respiratory symptoms nor disease rates were increased among adults or children near any of these plants, but one plant seemed to give rise to annoyance. For the remaining coal-fired plants, consistently higher prevalences of respiratory tract symptoms and annoyance were observed in the surrounding population. The effects cannot, however, conclusively be related to the coal-fired plants. It should be pointed out that the air pollution levels were relatively low, also in the vicinity of most of the plants in this study.

Air Pollutants, Occupational↗
PubMed1982

Cigarette smoking and alcohol use in Finland and Sweden: a cross-national twin study.

Cigarette smoking and alcohol use habits in Finland and Sweden were studied using data from the Finnish and Swedish studies on like-sexed adult twin pairs aged 18-47 (total of 20 056 pairs). Finnish men were heavier consumers of tobacco and alcohol than Swedish men. When heavy consumers (greater than 500g of alcohol/month and greater than 20 cigarettes/day) were considered, the prevalence rate was 9.7% in Finnish men and 5.1% in Swedish men. This difference might account for the higher morbidity in Finland than in Sweden from many smoking- and alcohol-associated diseases. Genetic factors in smoking and alcohol use were assessed by comparing observed and expected coincidence rates, and by multivariate analyses. Genetic and familial effects were defined as an excess coincidence in monozygotic (MZ) pairs compared to dizygotic (DZ) pairs, and by an increased DZ coincidence rate compared to that expected. Significant genetic and familial effects were observed for cigarette smoking, and for smoking more than one pack of cigarettes a day. Significant familial effects for alcohol use was observed, and a significant genetic effect was obtained for men. A significant genetic effect could not be observed for the combined heavy use of alcohol and heavy smoking. The genetic and familial effects seemed to be mostly independent of country and sex.

Adult↗