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Biomedical subjects

Niklas Hammar

Publications and source records attributed to Niklas Hammar.

At least 19 recordsLinked to original sources
PubMed2007

The new Swedish Prescribed Drug Register--opportunities for pharmacoepidemiological research and experience from the first six months.

PURPOSE: To describe the content and potentials of the new Swedish national register on prescribed and dispensed medicines. METHODS: The Swedish Prescribed Drug Register contains information about age, sex and unique identifier of the patient as well as the prescriber's profession and practice. Information regarding drug utilization and expenditures for prescribed drugs in the entire Swedish population was extracted from the first six months July-December 2005 and compared with total drug sales in the country including OTC and hospital use. RESULTS: The total quantity of drugs sold in Sweden was 2666 million DDDs, corresponding to 1608 DDD/1000 inhabitants daily. The total expenditures were 1.6 billion Euro. The prescribed drugs, included in the register, accounted for 84% of the total utilization and 77% of the total expenditures. About half of all men and two-thirds of all women in the country purchased drugs. The proportion increased by age. The most common drugs for chronic treatment were diuretics among women (8.8% of the population) and antithrombotic agents among men (7.6%). Psychotropic drugs, corticosteroids and analgesics were more common among women, while men used antithrombotic agents, antidiabetic drugs, lipid lowering agents and ACE inhibitors to a greater extent. CONCLUSIONS: The new register provides valuable data on exposure to drugs and is useful to study patterns of drug utilization. The possibilities for record linkage to other health registers gives from an international perspective good opportunities to explore drug and disease associations and the risks, benefits, effectiveness and health economical effects of drug use.

Adolescent↗
PubMed2006

Stroke prophylaxis in atrial fibrillation: who gets it and who does not? Report from the Stockholm Cohort-study on Atrial Fibrillation (SCAF-study).

AIMS: Underuse of warfarin for stroke prophylaxis in atrial fibrillation (AF) is extensive and represents a major problem in clinical practice. To identify factors associated with warfarin treatment in eligible AF patients. METHODS AND RESULTS: The study population consisted of all Swedish resident AF patients at the Stockholm South General Hospital during 2002 (n=2796). Medical records were examined and complemented by data from the Swedish National Hospital Discharge Register. Sixty-eight percent of the patients (1898/2796) had indications, and no apparent contraindications for warfarin treatment. Of these 54% (1029/1898) got warfarin. Factors favouring warfarin treatment after adjustment for other factors were history of ischaemic stroke, an implanted pacemaker, treatment in a cardiology rather than internal medicine ward and valvular defect. Factors associated with a reduced likelihood of warfarin treatment were paroxysmal type of AF and age >80 years. Important risk factors for stroke in AF like heart failure, hypertension, and diabetes did not increase the chances of warfarin treatment. CONCLUSION: Risk stratification using known risk factors of stroke seems to affect warfarin treatment only to a minor degree in clinical practice. Undertreatment was particularly common in patients with paroxysmal AF and in patients aged >80 years and calls for improved clinical routines in accordance with international guidelines.

Aged↗
PubMed2006

Left main coronary artery stenosis no longer a risk factor for early and late death after coronary artery bypass surgery--an experience covering three decades.

OBJECTIVE: To analyse early and late mortality after coronary artery bypass grafting (CABG) in patients with and without left main coronary artery (LMCA) stenosis during the 30-year period 1970-1999. METHODS: A total of 1888 of 10,647 patients (18%) who underwent a first isolated CABG at the Karolinska Hospital in Stockholm, Sweden, during 1970-1999 had significant left main coronary artery stenosis. The Swedish National Cause of Death Register was used to determine mortality up to five years after the operation. RESULTS: The proportion of patients with LMCA stenosis of all CABG patients increased from 7% during the 1970s to 26% in 1999. During 1970-1984 early mortality was 5.8% in patients with LMCA stenosis compared with 1.5% in patients without LMCA stenosis (odds ratio (OR) 3.7 (95% confidence interval (CI) 1.8-7.6)). The corresponding rates during 1995-1999 were 2.0% versus 2.2% (OR 0.8 (95% CI 0.5-1.5)), respectively. The increased risk of early death in patients with LMCA stenosis was neutralised in males during 1985-1994 and in females during 1995-1999. Five-year survival in males was 88% after operations performed during 1994-1999 compared with 82% after CABG performed during 1970-1984. Five-year mortality, exclusive of early deaths, during 1970-1984 was higher in patients with LMCA stenosis (12.8%) than in those without (8.4%) (relative risk 1.7 (95% CI 1.1-2.5)). An increased risk of late mortality in patients with LMCA stenosis was neutralised in males during 1985-1994 and in females during 1995-1999. CONCLUSIONS: During 1970-1999 there was a decrease of early and five-year mortality in patients with LMCA stenosis after CABG despite increase of patient age and risk factors. There were gender differences so that the risk of death in patients with compared with in those without LMCA stenosis was neutralised in males during 1985-1994 and in females during 1994-1999. The continuous decline of mortality during three decades most likely reflects improvement of the peri- and postoperative management of patients undergoing CABG during this period.

Aged↗
PubMed2006

Risk of death or acute myocardial infarction 10 years after coronary artery bypass surgery in relation to type of diabetes.

BACKGROUND: The aim of this study was to assess the long-term risk of death or acute myocardial infarction (AMI) in patients with diabetes mellitus (DM) compared with that in patients without DM after coronary artery bypass grafting (CABG). METHODS: National registers were used to record death or AMI occurring in 6727 patients who had CABG during 1980 to 1995. Diabetes mellitus in 856 patients (13%) was classified as type 1 (6%) or type 2 treated with insulin (29%), oral drugs (46%), or diet (19%). RESULTS: The risk of death < or = 30 days of the operation was increased in patients with insulin-treated type 2 DM (odds ratio [OR] 4.6, 95% CI 2.5-8.4) and in those on oral antidiabetic drugs (OR 2.0, 95% CI 1.0-3.8), but not in diet-treated diabetic patients, compared with that in patients without diabetes. At 10 years, the relative risk of death or having an AMI was 1.8 (95% CI 1.5-2.2) in insulin-treated patients and 1.4 (95% CI 1.2-1.7) in patients on oral drugs. No increased risk of late death or AMI was observed in diet-treated patients with diabetes compared with patients without diabetes. Survival at 10 years without an AMI was 40% in insulin-treated type 2 diabetic patients, 48% if on oral drugs, and 59% if diet managed, compared with 66% in nondiabetic patients. CONCLUSION: Type 2 DM requiring insulin treatment or oral antidiabetic drugs is associated with an increased early and long-term risk of death or AMI after CABG, whereas diet-treated patients have a risk similar to that in patients without diabetes.

Adult↗
PubMed2006

High mortality after coronary bypass surgery in patients with high-grade left main coronary artery stenosis.

OBJECTIVE: To determine mortality after coronary artery bypass grafting (CABG) in relation to degree of left main coronary artery (LMCA) obstruction. DESIGN: All patients without LMCA stenosis (n=3370), with low-grade stenosis (n = 261), high-grade stenosis (n = 224) or total occlusion of the LMCA (n = 15) were followed for ten years after CABG performed during 1970-1989. RESULTS: Early mortality was 1.9% and 2.3%, respectively, if there was no or a low-grade LMCA stenosis vs. 6.3% if the stenosis was high-grade. Ten-year survival was 76% if no LMCA obstruction, 74% if low-grade stenosis and 64% if the stenosis was high-grade. Risk of early death (odds ratio 2.6, 95% CI 1.4-4.8) and mortality at ten years (relative risk 1.5, 95% CI 1.1-2.0) was higher in patients with high-grade stenosis than in those without LMCA stenosis. There was no increased long-term mortality in patients with low-grade stenosis or among the few patients with occlusion of the LMCA. CONCLUSIONS: High-grade LMCA stenosis was associated with a three-fold increased risk of early and fifty percent higher risk of late death than in patients without LMCA stenosis.

Aged↗
PubMed2006

Use of oral contraceptives and mortality during 14 years' follow-up of Norwegian women.

AIMS: The aim was to evaluate total and cardiovascular disease (CVD) mortality in relation to use of oral contraceptives (OC) in a cohort of women with a relatively high prevalence of smoking and high serum lipid levels. METHODS: In all 29,053 women aged 20-49 years were invited to a health survey in 1985-88. Of the total 82% attended and 20,282 women free of known CVD were included in this analysis. The relative risk (RR) of mortality during 14 years of follow-up was compared between OC users and non-users by means of proportional hazards regression. RESULTS: About 50% of 827 OC users were daily cigarette smokers, and the mean total cholesterol level in the cohort was 5.9 mmol/l. There were 518 deaths, of which 10 occurred among the women taking OC at baseline. Of three deaths from CVD among OC users, two occurred in the first year of follow-up. Among non-smokers using OC three women died during the follow-up; none of the deaths was due to CVD. Women using OC of any type had no different adjusted total mortality (RR 0.87; 95% CI 0.46-1.65) or CVD mortality (RR 1.41; 95% CI 0.44-4.56) compared with non-users. CONCLUSIONS: The results were consistent with previous evidence which does not indicate that mortality from all causes or CVD is elevated in women using OC.

Adult↗
PubMed2005

Creatinine clearance and risk of early mortality in patients undergoing coronary artery bypass grafting.

OBJECTIVES: We sought to evaluate renal function assessed on the basis of calculated creatinine clearance as a predictor of early mortality and postoperative complications in patients undergoing coronary artery bypass grafting and to assess whether calculated creatinine clearance is superior to serum creatinine concentration in predicting early death postoperatively. METHODS: Six thousand seven hundred eleven consecutive patients without dialysis-dependent renal insufficiency undergoing a first isolated coronary artery bypass grafting were included. Preoperative serum creatinine concentrations and creatinine clearance calculated by using the Cockroft-Gault formula were related to mortality within 30 days postoperatively. RESULTS: There were 136 early deaths. After adjustment for age and other confounders in multivariate analyses, moderate (calculated creatinine clearance 30-60 mL/min) and severe (calculated creatinine clearance < 30 mL/min) renal insufficiency predicted early mortality (odds ratio of 2.4 [95% confidence interval, 1.2-4.8] and odds ratio of 4.8 [95% confidence interval], 1.6-13.9, respectively) compared with normal (calculated creatinine clearance > or = 90 mL/min) renal function. The area under the receiver operating characteristic curve for calculated creatinine clearance and serum creatinine concentration was 0.71 and 0.62, respectively, yielding a difference of 0.08 (P = .0004). No increased risk of mediastinitis or bleeding was observed in patients with renal insufficiency. CONCLUSION: Moderate and severe renal insufficiency independently increase the risk of early death after coronary artery bypass grafting. Our results indicate that calculated creatinine clearance is a better predictor of early mortality postoperatively than serum creatinine concentration.

Aged↗
PubMed2005

Migration and smoking: an epidemiological study of Finnish twins in Sweden.

BACKGROUND: Male migrants from Finland to Sweden have been found to have a reduced risk of coronary heart disease after several years in Sweden. Changes in smoking habits may contribute to this reduced risk. AIMS: A study was undertaken to compare smoking habits in Finnish migrants to Sweden and subjects always living in Finland and to analyse whether the migration may have influenced smoking. METHODS: The study population consisted of same-sex twin pairs born in Finland younger than 76 years with at least one twin that had migrated to Sweden (n = 1,083 pairs). Smoking habits obtained by mailed questionnaire were compared in migration-discordant twin pairs to take into account early childhood and genetic factors. RESULTS: Immigrants and returnees with a history of smoking had predominantly started to smoke before the migration. Among women, immigrants to Sweden smoked more than never migrants in Finland, odds ratio (OR) 2.1 for current smokers (95% confidence interval CI 1.4-3.3) but this difference was already present before migration. In men there were essentially no differences in smoking prevalence between immigrants and never migrants but heavy smoking was less common among immigrants than among never migrant smokers, OR 0.5 (95% CI 0.2-0.9) and migration was associated with a greater propensity to cease smoking. CONCLUSIONS: Migration from Finland to Sweden does not seem to have had a strong influence on smoking among migrants. A favourable trend in smoking habits after migration may in part have contributed to reduced mortality and incidence of coronary heart disease in male Finnish migrants after several years in Sweden.

Adult↗
PubMed2004

Shift workers' mortality scrutinized.

The objective of this article is to reappraise previous published data on the mortality of male shift workers from Taylor and Pocock (1972). Mortality rate ratios were calculated for shift workers, ex-shift workers, and for shift workers plus ex-shift workers, respectively, compared to day workers using the Mantel-Haenszel method. The overall risk for current and former shift workers was 1.05 (95% Confidence Interval: 0.95-1.16). For ex-shift workers the mortality was increased compared to day workers (1.24, 95% Confidence Interval: 1.03-1.51). In the age specific analyses increased mortality was observed in shift workers compared with day workers in the age group of 45-54 yrs (Relative Risk: 1.47, 95% Confidence Interval: 1.12-1.93). We suggest that shift work is associated with increased mortality risk.

Adult↗
PubMed2003

Mortality from cancer and other causes among male airline cockpit crew in Europe.

Airline pilots and flight engineers are exposed to ionizing radiation of cosmic origin and other occupational and life-style factors that may influence their health status and mortality. In a cohort study in 9 European countries we studied the mortality of this occupational group. Cockpit crew cohorts were identified and followed-up in Denmark, Finland, Germany, Great Britain, Greece, Iceland, Italy, Norway and Sweden, including a total of 28,000 persons. Observed and expected deaths for the period 1960-97 were compared based on national mortality rates. The influence of period and duration of employment was analyzed in stratified and Poisson regression analyses. The study comprised 547,564 person-years at risk, and 2,244 deaths were recorded in male cockpit crew (standardized mortality ratio [SMR] = 0.64, 95% confidence interval [CI] = 0.61-0.67). Overall cancer mortality was decreased (SMR = 0.68; 95% CI = 0.63-0.74). We found an increased mortality from malignant melanoma (SMR = 1.78, 95% CI = 1.15-2.67) and a reduced mortality from lung cancer (SMR = 0.53, 95% CI = 0.44-0.62). No consistent association between employment period or duration and cancer mortality was observed. A low cardiovascular mortality and an increased mortality caused by aviation accidents were noted. Our study shows that cockpit crew have a low overall mortality. The results are consistent with previous reports of an increased risk of malignant melanoma in airline pilots. Occupational risk factors apart from aircraft accidents seem to be of limited influence with regard to the mortality of cockpit crew in Europe.

Accidents, Aviation↗
PubMed2003

Mortality from cancer and other causes among airline cabin attendants in Europe: a collaborative cohort study in eight countries.

There is concern about the health effects of exposure to cosmic radiation during air travel. To study the potential health effects of this and occupational exposures, the authors investigated mortality patterns among more than 44,000 airline cabin crew members in Europe. A cohort study was performed in eight European countries, yielding approximately 655,000 person-years of follow-up. Observed numbers of deaths were compared with expected numbers based on national mortality rates. Among female cabin crew, overall mortality (standardized mortality ratio (SMR) = 0.80, 95% confidence interval (CI): 0.73, 0.88) and all-cancer mortality (SMR = 0.78, 95% CI: 0.66, 0.95) were slightly reduced, while breast cancer mortality was slightly but nonsignificantly increased (SMR = 1.11, 95% CI: 0.82, 1.48). In contrast, overall mortality (SMR = 1.09, 95% CI: 1.00, 1.18) and mortality from skin cancer (for malignant melanoma, SMR = 1.93, 95% CI: 0.70, 4.44) among male cabin crew were somewhat increased. The authors noted excess mortality from aircraft accidents and from acquired immunodeficiency syndrome in males. Among airline cabin crew in Europe, there was no increase in mortality that could be attributed to cosmic radiation or other occupational exposures to any substantial extent. The risk of skin cancer among male crew members requires further attention.

Adult↗
PubMed2003

Obesity and the risk of early and late mortality after coronary artery bypass graft surgery.

BACKGROUND: Obesity is often considered to be a significant risk factor for postoperative mortality when selecting candidates for coronary artery bypass grafting (CABG). METHODS: We included all patients undergoing a first isolated CABG at the Karolinska Hospital in Stockholm, Sweden, between 1980 and 1995 (n = 6728). Patients were categorized on the basis of body mass index (BMI): non-overweight (BMI <25 kg/m2), overweight (25 kg/m2 < or = BMI <30 kg/m2), and obese (BMI > or =30 kg/m2). Multivariate Cox regression was used to assess the risk of re-operation for bleeding, deep sternal wound infection, and early (< or =30 days) and late (< or =5 years) mortality rates. RESULTS: The average length of follow-up was 6.5 years. There were 252 re-operations for bleeding, 53 deep sternal wound infections, and 628 deaths. Patients who were obese had a significantly lower risk of re-operation for bleeding (risk ratio [RR], 0.32; 95% CI, 0.19-0.53), but a greater risk of deep sternal wound infection (RR, 2.66; 95% CI, 1.21-5.88) compared with patients who were not overweight. However, patients who were obese and patients who were not overweight experienced similar 30-day (RR, 0.65; 95% CI, 0.34-1.27), 1-year (RR, 0.56; 95% CI, 0.29-1.10), and 5-year mortality rates (RR, 0.91; 95% CI, 0.66-1.25). Results for patients who were overweight were consistent with those of patients who were obese. CONCLUSION: Patients who are obese are not at a greater risk of early and late mortality after CABG compared with patients who are not overweight, although they appear to have a lower risk of re-operation for bleeding and a greater risk of deep sternal wound infection. Therefore, obesity per se is not a contraindication for CABG.

Angina Pectoris↗
PubMed2003

Enhanced endothelium-dependent vasodilation in subjects with Proline7 substitution in the signal peptide of neuropeptide Y.

Neuropeptide Y (NPY) is a molecule that may have both vasoconstrictive and vasodilatory actions. A common polymorphism in the human NPY gene that results in the Leucine7 to Proline7 substitution (Leu7Pro) in the signal peptide part of the NPY was recently identified. This substitution has been associated with elevated serum cholesterol levels and with slightly accelerated progression rate of carotid intima-media thickness, thus suggesting increased risk of atherosclerosis in carriers of Pro7 substitution. Recent data also indicate that subjects with Pro7 substitution may have increased endothelial release of NPY. This study was undertaken to elucidate the effects of Leu7Pro polymorphism on arterial endothelial function. We measured flow-mediated endothelial-dependent dilatation (FMD) of the brachial artery in two separate populations: in 152 middle-aged men and in 95 prepubertal children. In both study populations, subjects with Pro7 substitution had 48-52% higher FMD compared with subjects having the wildtype (Leu7/Leu7) signal peptide sequence. We conclude that Pro7 substitution in signal peptide of the NPY is associated with enhanced endothelial-dependent vasodilation. Prospective studies are needed to determine whether Pro7 substitution is associated with increased or decreased risk of cardiovascular morbidity and mortality.

Adult↗
PubMed2003

Assessment of alcohol consumption by mailed questionnaire in epidemiological studies: evaluation of misclassification using a dietary history interview and biochemical markers.

BACKGROUND: Self-reported information on alcohol from questionnaires is generally assumed to introduce misclassification of consumption, mainly in the direction of underestimation. The aim of this study was to evaluate self-reported information on alcohol consumption from a mailed questionnaire by comparing to a dietary history interview and biochemical markers of alcohol intake. SUBJECTS AND METHODS: For 76 male twin pairs of the Finnish Twin Cohort Study aged 40-70 years information on self-reported alcohol consumption was collected through mailed questionnaire and dietary history interview. Carbohydrate-deficient transferrin (CDT), Gamma-glutamyltransferase (Gamma-GT) and mean corpuscular volume (MCV) were determined from blood samples. RESULTS: Mean levels of CDT, gamma-GT and MCV showed a rise with increased self-reported alcohol consumption already at low levels of reported consumption (<20 g alcohol/day). There was a positive correlation between reported amount alcohol intake per day and levels of CDT (r = 0.46), gamma-GT (r = 0.32) and MCV (r = 0.36) but within the high consumption group (> or = 30 g/day) there was no such correlation. The questionnaire had sensitivity of 28-43% and specificity of 89% for identification of high consumers of alcohol using the biochemical markers as reference and sensitivity 41% and specificity 94% using the dietary history interview as reference. Sensitivity was improved when information on binge drinking (82%) or possible drinking problems (73%) was considered. CONCLUSION: Comparison to dietary history interview as well as to biochemical markers indicate that self-reported information on alcohol consumption from a mailed questionnaire may be used to distinguish between groups with different levels of alcohol consumption. The suggested misclassification of high consumers implies that only strong associations between high alcohol intake and disease are likely to be detected in studies based on questionnaire data.

Adult↗
PubMed2003

Higher prevalence of Chlamydia pneumoniae seropositivity in Finnish twins compared with co-twins living in Sweden: relationships with markers of subclinical atherosclerosis.

Mortality rates from coronary heart disease are lower in Swedish men and among Finnish migrants who have lived in Sweden for over 20 years than in men living in Finland. Sero-epidemiological studies, investigations of atheromatous plaque specimens, in vitro animal models and anti-chlamydial antibiotic trials have given support to the hypothesis that Chlamydia pneumoniae (Cpn) has a role in atherosclerosis. We investigated whether men with a similar genetic background but living permanently in Finland or Sweden have differences in the prevalence of Cpn seropositivity, and whether chronic Cpn infection is associated with markers of subclinical atherosclerosis. We measured anti-Cpn antibodies and ultrasonographic markers of subclinical atherosclerosis, including carotid intima-media thickness, carotid artery compliance and brachial artery flow-mediated dilatation, in a population of 76 migrant-discordant male twin pairs (152 men). The number of men with seropositivity to Cpn infection (defined as IgA>/=1:64 and IgG>/=1:128) was greater in Finland than in Sweden (21.5% compared with 10.5%; P =0.046). Cpn seropositivity accompanied by elevated C-reactive protein (CRP) levels (>1 mg/l) was associated with attenuated brachial artery flow-mediated dilatation (3.3+/-0.3%, compared with 5.5+/-0.4% in men with no signs of Cpn infection; P <0.001).Thus, among Finnish twin brothers discordant for migration to Sweden, the prevalence of Cpn seropositivity is higher for those living in Finland, and men with Cpn seropositivity combined with elevated CRP levels had attenuated endothelial function. These findings offer insight into the mechanism whereby chronic Cpn infection may increase the risk of coronary heart disease.

Antibodies, Fungal↗
PubMed2003

Abstention, alcohol use and risk of myocardial infarction in men and women taking account of social support and working conditions: the SHEEP case-control study.

AIMS: Very few studies indicating that low-moderate alcohol consumption protects from myocardial infarction (MI) controlled for social support and working conditions, which could confound the findings. Therefore, a first aim was to study the risk of non-fatal and total MI in relation to volume of alcohol consumption and measures of social support and working conditions. A second aim was to analyse the impact of the volume of earlier alcohol use in abstainers. DESIGN: Data came from a case-control study, the Stockholm Heart Epidemiology Program (SHEEP), including first MI among Swedish citizens 45-70 years old. SETTING: Stockholm County 1992-94. PARTICIPANTS: There were 1095 cases of MI in men and 471 in women (928 and 372 were non-fatal), and 2339 living controls from the general population. MEASUREMENT: Information about alcohol use at different periods in life and job strain, social anchorage and life control besides pre-existing health problems, smoking, physical activity, socio-economic status and marital status was obtained by a questionnaire from the cases and the controls. FINDINGS: In multivariate logistic regression analyses, the relative risk for MI (especially non-fatal) was reduced among alcohol consumers. RR for non-fatal MI was 0.52 (95% confidence intervals 0.32, 0.85) in men with a consumption of 50-69.9 g 100% ethanol/day and 0.21 (95% confidence interval 0.06, 0.77) in women with a consumption of 30 g or more per day (reference category 0.1-5 g 100% ethanol/day). Men who were abstainers during the previous 1-10 years and with an earlier average consumption of 5-30 g 100% ethanol/day had a significantly lower relative risk compared to such abstainers with an earlier higher consumption. Earlier consumption among abstainers may also have an impact on gender differences in MI. Analyses showed positive interaction between abstention and low life-control in women, but only 4% of the female cases were due to this interaction. There were no other interactions between measures of alcohol use and social anchorage, life control and working situations. CONCLUSION: Alcohol use had a protective impact on MI, with little impact of job strain, social anchorage and life control, giving increased support for a protective impact of low-moderate alcohol use. The level of previous alcohol consumption among male 1-10-year-long abstainers influenced the risk of MI.

Aged↗