Impact of time since diagnosis and mortality rate on cancer-associated venous thromboembolism: the Scandinavian Thrombosis and Cancer (STAC) cohort.

Essentials Competing risk by death may lead to overestimation of venous thromboembolism (VTE) risk in cancers. We assessed the risk of VTE in cancer with and without accounting for competing risk by death. The risk of VTE was influenced by the mortality rate and the time since cancer diagnosis. Competing risk by death should be taken into account when exploring VTE risk in cancer. SUMMARY: Background Venous thromboembolism (VTE) is a common complication in cancer, and studies have suggested that aggressive cancers create the highest risk of VTE. However, competing risk by death may result in overestimation of VTE risk in patients with cancers associated with high mortality. Therefore, we estimated the risk of VTE by cancer site, accounting for the differential mortality between cancers. Methods The Scandinavian Thrombosis and Cancer cohort included 144 952 participants followed from 1993-1997 to 2008-2012. Incidence rates, cause-specific hazard ratios (HRs) and subdistribution HRs (SHRs) were assessed for overall cancer and by cancer site according to time intervals since cancer diagnosis. Results During follow-up, 14 272 subjects developed cancer, and 567 had cancer-related VTE. In cause-specific analyses, the VTE risk was highest in the first 6 months after cancer diagnosis (HR 17.5, 95% confidence interval [CI] 15.1-20.3), and declined rapidly thereafter. However, when mortality was taken into account, the risk was similar in the periods 6 months before (SHR 4.8, 95% CI 3.6-6.4) and 6 months after (SHR 4.6, 95% CI 3.9-5.4) cancer diagnosis. The range of the 2-year cumulative VTE incidence rates was substantially narrowed for all cancer sites after competing risk by death was taken into account (from 1-10% to 1-4%). Conclusion VTE risk by cancer site was influenced by the mortality rate and the time since cancer diagnosis. Our findings suggest that the cancer itself is a major contributor to VTE risk, and that competing risk by death should be taken into account when VTE risk in cancer is explored.

The impact of initial cancer stage on the incidence of venous thromboembolism: the Scandinavian Thrombosis and Cancer (STAC) Cohort.

Essentials Impact of cancer stage on venous thromboembolism (VTE) risk is not well-known in all cancers. The Scandinavian Thrombosis and Cancer Cohort provides person-time data and validated VTEs. Impact of cancer stage on VTE incidence tended to vary with cancer type. Cancer stage may not per se be a risk factor for VTE in all cancer types. SUMMARY: Background Absolute measures of the impact of cancer stage on the incidence of venous thromboembolism (VTE) in patients with distinct cancer types have not been investigated in a large population-based cohort study. Objectives To investigate differences in the incidence rates of objectively confirmed VTE according to the development of cancer in a large population-based cohort study. Cancer type and stage at the time of diagnosis were taken into account. Patients and Methods The Scandinavian Thrombosis and Cancer Cohort includes data regarding cancer types, stages and objectively confirmed VTE diagnoses among 144 952 participants followed from 1993 to 2012. We studied stage-specific incidence rates of VTE, and calculated incidence rate differences (IRDs) for VTE according to stages in patients with 10 types of solid cancer. Results During the entire follow-up, 335 VTEs occurred, of which 293 occurred within 5 years. The IRD of VTE in patients with distant metastasis as compared with those with localized disease indicated large variation depending on cancer type. The highest IRD was observed for pancreatic cancer (IRD of 187.0 × 10-3 person-years [p-y]; 95% confidence interval [CI] - 6.7 to 380.8), and the lowest IRD was observed for prostate cancer (IRD of 3.7 × 10-3 p-y; 95% CI - 7 to 15.2). Regional spread as compared with localized disease also indicated large variation depending on cancer type; the highest IRD was observed for uterine cancer (IRD of 37.6 × 10-3 p-y; 95% CI - 23.7 to 99), and the IRDs for breast and prostate cancer were close to zero. Conclusion More advanced cancer at the time of diagnosis was associated with a higher risk of VTE, but the strength of the associations differed substantially between cancer types.

Venous thromboembolism and subsequent permanent work-related disability.

Essentials The burden of venous thromboembolism (VTE) related to permanent work-related disability is unknown. In a cohort of 66 005 individuals, the risk of work-related disability after a VTE was assessed. Unprovoked VTE was associated with 52% increased risk of work-related disability. This suggests that indirect costs due to loss of work time may add to the economic burden of VTE. SUMMARY: Background The burden of venous thromboembolism (VTE) related to permanent work-related disability has never been assessed among a general population. Therefore, we aimed to estimate the risk of work-related disability in subjects with incident VTE compared with those without VTE in a population-based cohort. Methods From the Tromsø Study and the Nord-Trøndelag Health Study (HUNT), Norway, 66 005 individuals aged 20-65 years were enrolled in 1994-1997 and followed to 31 December 2008. Incident VTE events among the study participants were identified and validated, and information on work-related disability was obtained from the Norwegian National Insurance Administration database. Cox-regression models using age as time-scale and VTE as time-varying exposure were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) adjusted for sex, body mass index, smoking, education level, marital status, history of cancer, diabetes, cardiovascular disease and self-rated general health. Results During follow-up, 384 subjects had a first VTE and 9862 participants were granted disability pension. The crude incidence rate of work-related disability after VTE was 37.5 (95% CI, 29.7-47.3) per 1000 person-years, vs. 13.5 (13.2-13.7) per 1000 person-years among those without VTE. Subjects with unprovoked VTE had a 52% higher risk of work-related disability than those without VTE (HR, 1.52; 95% CI, 1.09-2.14) after multivariable adjustment, and the association appeared to be driven by deep vein thrombosis. Conclusion VTE was associated with subsequent work-related disability in a cohort recruited from the general working-age population. Our findings suggest that indirect costs because of loss of work time may add to the economic burden of VTE.

The relationship between body mass index, activated protein C resistance and risk of venous thrombosis.

BACKGROUND: High body mass index (BMI) is associated with an increased risk of venous thrombosis (VT). Clotting factor VIII levels are increased in obese subjects, possibly because of a chronic inflammatory state, which increases activated protein C (APC) resistance. The APC resistance in FV Leiden carriers could be aggravated and further worsened by high FVIII levels in blood group non-O carriers. We hypothesized that an association exists between BMI and APC resistance, and that this is amplified by the presence of FV Leiden and/or blood group non-O. METHODS: We used the Leiden Thrombophilia Study (LETS) to determine whether an association exists between BMI and APC resistance, and whether the combination of high BMI and APC resistance increases the risk of VT. In a pooled analysis of LETS and a Norwegian case-cohort study (TROL), we verified whether FV Leiden modified the risk of the occurrence of VT with increasing BMI, and whether this risk was further increased by blood group non-O. RESULTS: APC resistance increased linearly with increasing BMI, partly because of a concurrent rise in FVIII. A BMI in the median or upper tertile was associated with a 1.9-fold (95% confidence interval [CI] 1.0-2.5) and 2.2-fold (95% CI 1.4-3.4) increased risk as compared with the lowest tertile. Both relative risks decreased slightly after FVIII and APC resistance adjustments. The effect of BMI on VT risk was enhanced two-fold to 10-fold in FV Leiden or blood group non-O carriers. CONCLUSIONS: The increased risk of VT in individuals with high BMI is partly mediated by FVIII-related APC resistance. This risk is more pronounced when other causes of increased APC resistance are also present.

Increased levels of free thyroxine and risk of venous thrombosis in a large population-based prospective study.

BACKGROUND: Recent studies have shown that high levels of free thyroxine (FT4), even without leading to hyperthyroidism, are associated with a procoagulant state. OBJECTIVES: The aim of our study was to determine whether high levels of thyroid hormones are associated with an increased risk of venous thrombosis. PATIENTS/METHODS: From a prospective nested case-cohort design within the second Nord-Trøndelag Health Study (HUNT2) cohort (1995-1997; 66,140 subjects), all patients with venous thrombosis during follow-up (n=515) and 1476 randomly selected age-stratified and sex-stratified controls were included. Relative and absolute risks for venous thrombosis were calculated for different cut-off levels of thyroid hormones on the basis of percentiles in the controls and different times between blood sampling and thombosis. RESULTS: In subjects with an FT4 level above the 98th percentile (17.3 pmol L(-1)), the odds ratio (OR) was 2.5 (95% confidence interval [CI] 1.3-5.0) as compared with subjects with levels below this percentile. For venous thrombosis within 1 year from blood sampling, this relative risk was more pronounced, with an OR of 4.8 (95% CI 1.7-14.0). Within 0.5 years, the association was even stronger, with an OR of 9.9 (95% CI 2.9-34.0, adjusted for age, sex, and body mass index). For thyroid-stimulating hormone, the relationship was inverse and less pronounced. The absolute risk within 6 months in the population for FT4 levels above the 98th percentile was 6.1 per 1000 person-years (95% CI 1.7-15.7). CONCLUSIONS: Levels of FT4 at the upper end of the normal range are a strong risk factor for venous thrombosis. The risk increased with higher levels of thyroxine and shorter time between blood sampling and thrombosis. Further studies on the effect of clinical hyperthyroidism are warranted.

Incidence and mortality of venous thrombosis: a population-based study.

BACKGROUND: Estimates of the incidence of venous thrombosis (VT) vary, and data on mortality are limited. OBJECTIVES: We estimated the incidence and mortality of a first VT event in a general population. METHODS: From the residents of Nord-Trøndelag county in Norway aged 20 years and older (n = 94 194), we identified all cases with an objectively verified diagnosis of VT that occurred between 1995 and 2001. Patients and diagnosis characteristics were retrieved from medical records. RESULTS: Seven hundred and forty patients were identified with a first diagnosis of VT during 516,405 person-years of follow-up. The incidence rate for all first VT events was 1.43 per 1000 person-years [95% confidence interval (CI): 1.33-1.54], that for deep-vein thrombosis (DVT) was 0.93 per 1000 person-years (95% CI: 0.85-1.02), and that for pulmonary embolism (PE) was 0.50 per 1000 person-years (95% CI: 0.44-0.56). The incidence rates increased exponentially with age, and were slightly higher in women than in men. The 30-day case-fatality rate was higher in patients with PE than in those with DVT [9.7% vs. 4.6%, risk ratio 2.1 (95% CI: 1.2-3.7)]; it was also higher in patients with cancer than in patients without cancer [19.1% vs. 3.6%, risk ratio 3.8 (95% CI 1.6-9.2)]. The risk of dying was highest in the first months subsequent to the VT, after which it gradually approached the mortality rate in the general population. CONCLUSIONS: This study provides estimates of incidence and mortality of a first VT event in the general population.

A prospective study of anticardiolipin antibodies as a risk factor for venous thrombosis in a general population (the HUNT study).

We prospectively examined whether there is an association between elevated anticardiolipin antibody levels and the risk for a future first venous thrombosis (VT) in a general population. We studied this in a large population-based nested case-cohort study of 508 VT cases and 1464 matched control subjects from a cohort of 66,140 participants in the Health Study of Nord-Trøndelag in Norway. Venous thrombosis was validated using standardized criteria for venous thrombosis and pulmonary embolism. Prethrombotic serum anticardiolipin antibodies were measured by an enzyme-linked immunoassay. There was no association between elevated anticardiolipin antibody levels and subsequent venous thrombosis, overall or after stratification by sex, different age groups or idiopathic vs. secondary thrombosis. The overall odds ratio was 1.11 (95% CI: 0.71-1.74) for greater than vs. less than the 95th percentile of anticardiolipin antibody levels. In conclusion, in this general population sample elevated anticardiolipin antibody levels was not a risk factor for subsequent venous thrombosis.