Thyroid function, as assessed by TSH, and future risk of venous thromboembolism: the Tromsø study.

OBJECTIVE: The relationship between thyroid function and the risk of venous thromboembolism (VTE) has not been addressed in population-based cohorts. We investigated the association between TSH levels and the risk of VTE in a general adult population. DESIGN: Population-based cohort study. METHODS: TSH was measured in 11 962 subjects aged 25-89 years who participated in Tromsø 4-6 starting in 1994-1995. Incident VTE events were recorded through 31st December 2010. Cox's regression models with TSH as a time-varying covariate were used to calculate hazard ratios (HRs) of VTE by TSH categories (low TSH: <0.05  mU/l; moderately reduced TSH: 0.05-0.19  mU/l; normal TSH: 0.20-4.00  mU/l; moderately elevated TSH: 4.01-5.00  mU/l; and high TSH: >5.00 mU/l) and within the normal range of TSH, modeling TSH as a continuous variable. RESULTS: There were 289 VTEs during 8.2 years of median follow-up. Subjects with low (prevalence: 0.22%) and high (3.01%) TSH had slightly higher risk estimates for VTE than did subjects with normal TSH (multivariable HRs: 2.16, 95% CI 0.69-6.76 and 1.55, 95% CI 0.87-2.77 respectively), but the CIs were wide. Moreover, there was no association between TSH within the normal range and VTE (HR per 1 mU/l increase: 0.95, 95% CI 0.82-1.11). CONCLUSION: Serum levels of TSH within the normal range were not associated with a risk of VTE, whereas low and high TSH levels were rare and associated with a moderately higher risk of VTE. The present findings suggest that only a minor proportion of the VTE risk in the population can be attributed to thyroid dysfunction.

Family history of myocardial infarction and cause-specific risk of myocardial infarction and venous thromboembolism: the Tromsø Study.

BACKGROUND: A family history of myocardial infarction (FHMI) has been shown to increase the risk of venous thromboembolism (VTE). The mechanism underlying the association remains unclear. Therefore, we aimed to determine the risks of MI and VTE by FHMI using a cause-specific model and to explore whether atherosclerotic risk factors could explain the association between FHMI and VTE in a population-based cohort. METHODS AND RESULTS: The study included 21 624 subjects recruited from the Tromsø Study in 1994 to 1995 and 2001 to 2002. Incident MI and VTE events were registered from date of enrollment to end of follow-up, December 31, 2010. There were 1311 MIs and 428 VTEs during a median follow-up of 15.8 years. FHMI was associated with a 52% increased risk of MI (adjusted hazard ratio, 1.52; 95% confidence interval, 1.35-1.70) and a 26% increased risk of VTE (adjusted hazard ratio, 1.26; 95% confidence interval, 1.02-1.55) in the cause-specific Cox model. Similar results were found using the traditional Cox model. The risk estimates by status of FHMI were highest for unprovoked deep vein thrombosis (adjusted hazard ratio, 1.69; 95% confidence interval, 1.12-2.56), and the risk increased with increasing number of affected relatives. Modifiable atherosclerotic risk factors slightly altered the association between FHMI and MI but had a negligible effect on the association between FHMI and VTE. CONCLUSIONS: FHMI was associated with increased risk of both MI and VTE in a cause-specific model. Apparently, the association between FHMI and VTE applied to unprovoked deep vein thrombosis and was not explained by modifiable atherosclerotic risk factors.

High fish plus fish oil intake is associated with slightly reduced risk of venous thromboembolism: the Tromsø Study.

Current knowledge of the effect of fish consumption on risk of venous thromboembolism (VTE) is scarce and diverging. Therefore, the purpose of the present study was to investigate the impact of fish consumption and fish oil supplements on the risk of VTE in a population-based cohort. Weekly intake of fish for dinner and intake of fish oil supplements during the previous year were registered in 23,621 persons aged 25-97 y who participated in the Tromsø Study from 1994 to 1995. Incident VTE events were registered throughout follow-up (31 December 2010). Cox-regression models were used to calculate HRs for VTE, adjusted for age, body mass index, sex, triglycerides, HDL cholesterol, physical activity, and education level. During a median of 15.8 y of follow-up there were 536 incident VTE events. High fish consumption was associated with a slightly reduced risk of VTE. Participants who ate fish ≥3 times/wk had 22% lower risk of VTE than those who consumed fish 1-1.9 times/wk (multivariable HR: 0.78; 95% CI: 0.60, 1.01; P = 0.06). The addition of fish oil supplements strengthened the inverse association with risk of VTE. Participants who consumed fish ≥3 times/wk who additionally used fish oil supplements had 48% lower risk than those who consumed fish 1-1.9 times/wk but did not use fish oil supplements (HR: 0.52; 95% CI: 0.34, 0.79; P = 0.002). In conclusion, a high weekly intake (≥3 times/wk) of fish was associated with a slightly reduced risk of VTE, and the addition of fish oil supplements strengthened the inverse effect.

Venous thromboembolism increases the risk of atrial fibrillation: the Tromso study.

BACKGROUND: Pulmonary embolism (PE) may trigger atrial fibrillation through increased right atrial pressure and subsequent atrial strain, but the degree of evidence is low. In this study, we wanted to investigate the impact of incident venous thromboembolism (VTE) on future risk of atrial fibrillation in a prospective population-based study. METHODS AND RESULTS: The study included 29 974 subjects recruited from the Tromsø study (1994-1995, 2001-2002, 2007-2008). Incident VTE and atrial fibrillation events were registered from date of enrolment to end of follow-up, December 31, 2010. Cox proportional hazard regression models using age as time-scale and VTE as a time-dependent variable were used to estimate crude and multivariable hazard ratios (HRs) for atrial fibrillation with 95% confidence intervals (CIs). During 16 years of follow up, 540 (1.8%) subjects had an incident VTE event, and 1662 (5.54%) were diagnosed with atrial fibrillation. Among those with VTE, 50 (9.3%) developed subsequent atrial fibrillation. Patients with VTE had 63% higher risk of atrial fibrillation compared to subjects without VTE (multivariable-adjusted HR: 1.63, 95% CI: 1.22 to 2.17). The risk of atrial fibrillation was particularly high during the first 6 months after the VTE event (HR 4.00, 95% CI: 2.21 to 7.25) and among those with PE (HR 1.78, 95% CI: 1.13 to 2.80). CONCLUSIONS: We found that incident VTE was associated with future risk of atrial fibrillation. Our findings support the hypothesis that PE may lead to cardiac dysfunctions that, in turn, could trigger atrial fibrillation.

Impact of incident venous thromboembolism on risk of arterial thrombotic diseases.

BACKGROUND: Growing evidence supports an association between venous thromboembolism (VTE) and arterial thrombotic diseases (ie, myocardial infarction and ischemic stroke). We aimed to study the association between VTE and future arterial events and to determine the population attributable risk of arterial events by VTE in a large prospective cohort recruited from the general population. METHODS AND RESULTS: In 1994 to 1995 and 1993 to 1997, 81 687 subjects were included in the Tromsø Study and in the Diet, Cancer and Health Study and followed up to the date of incident venous and arterial events (myocardial infarction or ischemic stroke), death or migration, or to the end of the study period (2010 and 2008, respectively). There were 1208 cases of VTE and 90 subsequent arterial events during a median follow-up of 12.2 years. An association between VTE and future arterial events was found in all women and men aged <65 years but not in men aged >65 years. Women <65 years old with VTE had 3.3-fold higher risk of arterial disease (adjusted hazard ratio, 3.28; 95% confidence interval, 1.69-6.35) compared with women of the same age without VTE. The corresponding hazard ratio in men aged <65 years was 2.06 (95% confidence interval, 1.32-3.20). Only 0.9% of the arterial events were attributed to VTE, and the VTE explained 63.8% of the risk of arterial events among VTE patients. CONCLUSIONS: Our findings imply that women and young men with VTE have higher risk of arterial thrombotic disease than those without VTE. However, only 1% of the arterial thrombotic events in the population are attributed to VTE.

Heart healthy diet and risk of myocardial infarction and venous thromboembolism. The Tromsø Study.

Prudent dietary patterns are associated with reduced risk of arterial cardiovascular diseases (CVD). Limited data exist on the relation between diet and venous thromboembolism (VTE). The aim of our prospective, population based study was to investigate the association of a heart healthy diet on risk of myocardial infarction (MI) and VTE. Information on dietary habits was available in 18,062 subjects, aged 25-69, who participated in the fourth Tromsø study, 1994-1995. Dietary patterns were assessed by a slightly modified version of the validated SmartDiet score; a 13-item questionnaire producing a diet score based on the intakes of fat, fibre, fruit and vegetables. Incident events of MI (n=518) and VTE (n=172) were recorded to the end of follow-up December 31, 2005 (median follow-up 10.8 years). Cox-regression models were used to calculate hazard ratios (HR). A healthy diet score of >27 points (upper tertile) was associated with 17% reduced risk of MI (HR: 0.83, 95% confidence interval [CI]: 0.66-1.06), and no association with VTE (HR: 1.01; 95%CI: 0.66-1.56), compared to <24 points (lower tertile) in multivariable analysis. High intake of fish, fruit, vegetables and polyunsatured fat had a 23% reduced risk of MI (HR 0.77; 95%CI: 0.60-0.98), but no association with VTE (HR 0.95; 95%CI: 0.64-1.40). A heart healthy diet showed an even more favourable association with MI in obese subjects (HR: 0.62; 95%CI: 0.41-0.95), but not with VTE. Our findings suggest that a heart healthy dietary pattern is associated with moderately reduced risk of MI, but not related to risk of VTE.

Emotional states and future risk of venous thromboembolism: the Tromsø Study.

Emotional states of depression and loneliness are reported to be associated with higher risk and optimism with lower risk of arterial cardiovascular disease (CVD) and death. The relation between emotional states and risk of venous thromboembolism (VTE) has not been explored previously. We aimed to investigate the associations between self-reported emotional states and risk of incident VTE in a population-based, prospective study. The frequency of feeling depressed, lonely and happy/optimistic were registered by self-administered questionnaires, along with major co-morbidities and lifestyle habits, in 25,964 subjects aged 25-96 years, enrolled in the Tromsø Study in 1994-1995. Incident VTE-events were registered from the date of inclusion until September 1, 2007. There were 440 incident VTE-events during a median of 12.4 years of follow-up. Subjects who often felt depressed had 1.6-fold (95% CI:1.02-2.50) higher risk of VTE compared to those not depressed in analyses adjusted for other risk factors (age, sex , body mass index, oestrogens), lifestyle (smoking, alcohol consumption, educational level) and co-morbidities (diabetes, CVD, and cancer). Often feeling lonely was not associated with VTE. However, the incidence rate of VTE in subjects who concurrently felt often lonely and depressed was higher than for depression alone (age-and sex-adjusted incidence rate: 3.27 vs. 2.21). Oppositely, subjects who often felt happy/optimistic had 40% reduced risk of VTE (HR 0.60, 95% CI: 0.41-0.87). Our findings suggest that self-reported emotional states are associated with risk of VTE. Depressive feelings were associated with increased risk, while happiness/optimism was associated with reduced risk of VTE.

Alcohol consumption, types of alcoholic beverages and risk of venous thromboembolism - the Tromsø Study.

Moderate alcohol consumption has been shown to protect against cardiovascular diseases. The association between alcohol consumption, especially types of alcoholic beverages, and venous thromboembolism (VTE) is less well described. The aim of this study was to investigate the impact of alcohol consumption and different alcoholic beverages on risk of VTE. Information on alcohol consumption was collected by a self-administrated questionnaire in 26,662 subjects, aged 25-97 years, who participated in the Tromsø Study, in 1994-1995. Subjects were followed through September 1, 2007 with incident VTE as the primary outcome. There were 460 incident VTE-events during a median of 12.5 years of follow-up. Total alcohol consumption was not associated with risk of incident VTE. However, subjects consuming ≥ 3 units of liquor per week had 53% increased risk of VTE compared to teetotalers in analyses adjusted for age, sex, body mass index, smoking, diabetes, cancer, previous cardiovascular disease, physical activity and higher education (HR: 1.53, 95% CI: 1.00-2.33). Contrary, subjects with a wine intake of ≥ 3 units/week had 22% reduced risk of VTE (HR: 0.78, 95% CI: 0.47-1.30), further adjustment for liquor and beer intake strengthened the protective effect of wine (HR: 0.53, 95% CI: 0.30-1.00). Frequent binge drinkers (≥ 1/week) had a 17% increased risk of VTE compared to teetotallers (HR 1.17, 95% CI: 0.66-2.09), and a 47% increased risk compared to non-binge drinkers (HR 1.47, 95% CI: 0.85-2.54). In conclusion, liquor consumption and binge drinking was associated with increased risk of VTE, whereas wine consumption was possibly associated with reduced risk of VTE.