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Hematocrit and the risk of recurrent venous thrombosis: a prospective cohort study.

Eischer L, Tscholl V, Heinze G, Traby L, Kyrle PA, Eichinger S - PLoS ONE (2012)

Bottom Line: Venous thromboembolism (VTE) is a multicausal disease which recurs.Patients with a first VTE were followed after anticoagulation.Patients with VTE provoked by a transient risk factor, natural inhibitor deficiency, lupus anticoagulant, homozygous or double heterozygous defects, cancer, or long-term antithrombotic treatment were excluded.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine I, Medical University of Vienna, Vienna, Austria.

ABSTRACT

Background: Venous thromboembolism (VTE) is a multicausal disease which recurs. Hematocrit is associated with a thrombotic risk. We aimed to investigate if hematocrit is associated with the recurrence risk.

Methods: Patients with a first VTE were followed after anticoagulation. Patients with VTE provoked by a transient risk factor, natural inhibitor deficiency, lupus anticoagulant, homozygous or double heterozygous defects, cancer, or long-term antithrombotic treatment were excluded. The study endpoint was recurrent VTE.

Results: 150 (23%) of 653 patients had recurrence. Only high hematocrit was significantly associated with recurrence risk [hazard ratio (HR) for 1% hematocrit increase with the third tertile 1.08; 95% CI 1.01-1.15]. No or only a weak association for hematocrits within the first and second tertile was seen (HR 1.03; 95% CI 0.97-1.09, and 1.07; 95% CI 1.00-1.13). Hematocrit was associated with recurrence risk only among women. After five years, the probability of recurrence was 9.9% (95% CI 3.7%-15.7%), 15.6% (95% CI 9.7%-21.2%) and 25.5% (95% CI 15.1%-34.6%) in women, and was 29.2% (95% CI 21.1%-36.5%), 30.1% (95% CI 24.1%-35.7%) and 30.8% (95% CI 22.0%-38.7%) in men for hematocrits in the first, second and third tertile, respectively. Men had a higher recurrence risk (1.9; 95% CI 1.1-2.7; p = 0.03), which dropped by 23.5% after adjustment for hematocrit. Hematocrit was not a significant mediator of the sex-difference in recurrence risk (p = 0.223).

Conclusions: High hematocrit is associated with the recurrence only in women. The different recurrence risk between men and women is possibly partly explained by hematocrit.

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Related in: MedlinePlus

Cumulative recurrence rates (as estimated from the Cox regression model) in women and men according to tertile mean values of hematocrit, adjusted for location of first venous thromboembolism, body mass index, age, factor V Leiden, and smoking status.
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pone-0038705-g002: Cumulative recurrence rates (as estimated from the Cox regression model) in women and men according to tertile mean values of hematocrit, adjusted for location of first venous thromboembolism, body mass index, age, factor V Leiden, and smoking status.

Mentions: We further investigated whether the effect of hematocrit on recurrence risk differed between women and men using interaction analysis. Here, product terms of the transformed hematocrit values with sex (H1×sex and H2×sex) were introduced to the model. If different from zero, these product terms indicate a sex-related difference in the association between hematocrit and the risk of recurrence. Indeed, the two terms were simultaneously significantly different from zero (p = 0.024). This implied that the risk of recurrence associated with a 1% increase in hematocrit not only depended on the level of hematocrit but also on the sex of the patients. In order to illustrate this nonlinear sex-dependent effect of hematocrit, we computed the HRs at the sex-specific hematocrit tertile mean values (36.3%, 40.0% and 42.9% in women; 40.7%, 43.6% and 46.8% in men) (Table 2). While hematocrit had no relevant impact on the recurrence risk in men, its effect was strong and nonlinear in women. From this final Cox regression model we also derived the five-year cumulative recurrence rates in women and in men (Figure 1). Furthermore, we estimated and depicted the cumulative recurrence risk for women with hematocrits of 36%, 40% and 43% (corresponding to the tertile means of female patients), and for men of 41%, 44% and 47% (corresponding to the tertile means of men) (Figure 2). After five years, the probability of recurrence was 9.9% (95% CI 3.7%–15.7%), 15.6% (95% CI 9.7%–21.2%), and 25.5% (95% CI 15.1%–34.6%) in women with hematocrit ranging in the lowest to the highest tertile and was 29.2% (95% CI 21.1%–36.5%), 30.1% (95% CI 24.1%–35.7%), and 30.8% (95% CI 22.0%–38.7%) in men within the respective tertiles.


Hematocrit and the risk of recurrent venous thrombosis: a prospective cohort study.

Eischer L, Tscholl V, Heinze G, Traby L, Kyrle PA, Eichinger S - PLoS ONE (2012)

Cumulative recurrence rates (as estimated from the Cox regression model) in women and men according to tertile mean values of hematocrit, adjusted for location of first venous thromboembolism, body mass index, age, factor V Leiden, and smoking status.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368845&req=5

pone-0038705-g002: Cumulative recurrence rates (as estimated from the Cox regression model) in women and men according to tertile mean values of hematocrit, adjusted for location of first venous thromboembolism, body mass index, age, factor V Leiden, and smoking status.
Mentions: We further investigated whether the effect of hematocrit on recurrence risk differed between women and men using interaction analysis. Here, product terms of the transformed hematocrit values with sex (H1×sex and H2×sex) were introduced to the model. If different from zero, these product terms indicate a sex-related difference in the association between hematocrit and the risk of recurrence. Indeed, the two terms were simultaneously significantly different from zero (p = 0.024). This implied that the risk of recurrence associated with a 1% increase in hematocrit not only depended on the level of hematocrit but also on the sex of the patients. In order to illustrate this nonlinear sex-dependent effect of hematocrit, we computed the HRs at the sex-specific hematocrit tertile mean values (36.3%, 40.0% and 42.9% in women; 40.7%, 43.6% and 46.8% in men) (Table 2). While hematocrit had no relevant impact on the recurrence risk in men, its effect was strong and nonlinear in women. From this final Cox regression model we also derived the five-year cumulative recurrence rates in women and in men (Figure 1). Furthermore, we estimated and depicted the cumulative recurrence risk for women with hematocrits of 36%, 40% and 43% (corresponding to the tertile means of female patients), and for men of 41%, 44% and 47% (corresponding to the tertile means of men) (Figure 2). After five years, the probability of recurrence was 9.9% (95% CI 3.7%–15.7%), 15.6% (95% CI 9.7%–21.2%), and 25.5% (95% CI 15.1%–34.6%) in women with hematocrit ranging in the lowest to the highest tertile and was 29.2% (95% CI 21.1%–36.5%), 30.1% (95% CI 24.1%–35.7%), and 30.8% (95% CI 22.0%–38.7%) in men within the respective tertiles.

Bottom Line: Venous thromboembolism (VTE) is a multicausal disease which recurs.Patients with a first VTE were followed after anticoagulation.Patients with VTE provoked by a transient risk factor, natural inhibitor deficiency, lupus anticoagulant, homozygous or double heterozygous defects, cancer, or long-term antithrombotic treatment were excluded.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine I, Medical University of Vienna, Vienna, Austria.

ABSTRACT

Background: Venous thromboembolism (VTE) is a multicausal disease which recurs. Hematocrit is associated with a thrombotic risk. We aimed to investigate if hematocrit is associated with the recurrence risk.

Methods: Patients with a first VTE were followed after anticoagulation. Patients with VTE provoked by a transient risk factor, natural inhibitor deficiency, lupus anticoagulant, homozygous or double heterozygous defects, cancer, or long-term antithrombotic treatment were excluded. The study endpoint was recurrent VTE.

Results: 150 (23%) of 653 patients had recurrence. Only high hematocrit was significantly associated with recurrence risk [hazard ratio (HR) for 1% hematocrit increase with the third tertile 1.08; 95% CI 1.01-1.15]. No or only a weak association for hematocrits within the first and second tertile was seen (HR 1.03; 95% CI 0.97-1.09, and 1.07; 95% CI 1.00-1.13). Hematocrit was associated with recurrence risk only among women. After five years, the probability of recurrence was 9.9% (95% CI 3.7%-15.7%), 15.6% (95% CI 9.7%-21.2%) and 25.5% (95% CI 15.1%-34.6%) in women, and was 29.2% (95% CI 21.1%-36.5%), 30.1% (95% CI 24.1%-35.7%) and 30.8% (95% CI 22.0%-38.7%) in men for hematocrits in the first, second and third tertile, respectively. Men had a higher recurrence risk (1.9; 95% CI 1.1-2.7; p = 0.03), which dropped by 23.5% after adjustment for hematocrit. Hematocrit was not a significant mediator of the sex-difference in recurrence risk (p = 0.223).

Conclusions: High hematocrit is associated with the recurrence only in women. The different recurrence risk between men and women is possibly partly explained by hematocrit.

Show MeSH
Related in: MedlinePlus