Taller women are at greater risk of recurrent venous thromboembolism: the Iowa Women's Health Study

Venous valve hypoxia as a possible mechanism of deep vein thrombosis: a scoping review

INTRODUCTION

The pathogenesis of deep vein thrombosis (DVT) has been explained by an interplay between a changed blood composition, vein wall alteration, and blood flow abnormalities. A comprehensive investigation of these components of DVT pathogenesis has substantially promoted our understanding of thrombogenesis in the venous system. Meanwhile, the process of DVT initiation remains obscure. This systematic review aims to collect, analyze, and synthesize the published evidence to propose hypoxia as a possible trigger of DVT.

EVIDENCE ACQUISITION

An exhaustive literature search was conducted across multiple electronic databased including PubMed, EMBASE, Scopus, and Web of Science to identify studies pertinent to the research hypothesis. The search was aimed at exploring the connection between hypoxia, reoxygenation, and the initiation of deep vein thrombosis (DVT). The following key words were used: "deep vein thrombosis," "venous thrombosis," "venous thromboembolism," "hypoxia," "reoxygenation," "venous valve," and "venous endothelium." Reviews, case reports, editorials, and letters were excluded.

EVIDENCE SYNTHESIS

Based on the systematic search outcome, 156 original papers relevant to the issue were selected for detailed review. These studies encompassed a range of experimental and observational clinical research, focusing on various aspects of DVT, including the anatomical, physiological, and cellular bases of the disease. A number of studies suggested limitations in the traditional understanding of Virchow's triad as an acceptable explanation for DVT initiation. Emerging evidence points to more complex interactions and additional factors that may be critical in the early stages of thrombogenesis. The role of venous valves has been recognized but remains underappreciated, with several studies indicating that these sites may act as primary loci for thrombus formation. A collection of studies describes the effects of hypoxia on venous endothelial cells at the cellular and molecular levels. Hypoxia influences several pathways that regulate endothelial cell permeability, inflammatory response, and procoagulation activity, underpinning the endothelial dysfunction noted in DVT.

CONCLUSIONS

Hypoxia of the venous valve may serve as an independent hypothesis to outline the DVT triggering process. Further research projects in this field may discover new molecular pathways responsible for the disease and suggest new therapeutic targets.

Body Height and Incident Risk of Venous Thromboembolism: A Cosibling Design

BACKGROUND

Body height has been associated with an increased risk of venous thromboembolism (VTE), but the association can be confounded with shared familial factors (genetic/environmental). A cosibling design is useful for deeper understanding about the relationship between VTE and height.

METHODS AND RESULTS

From Swedish national registry databases, we used a corelative design with full siblings alongside a general Swedish population sample. A cohort of male conscripts (n=1 610 870), born in 1951 to 1992 without previous VTE, was followed from enlistment (1969-2010) until 2012. Another cohort of first-time pregnant women (n=1 093 342) from the medical birth register, without previous VTE, was followed from first pregnancy (1982-2012) until 2012. Using the Multi-Generation Register, we identified all full-sibling pairs discordant for height. This cosibling design allowed for adjustment for familial factors (genetic/environmental). Compared with the tallest women (>185 cm) and men (>190 cm), there was a graded decreased risk by lower height for both men and women. The risk was lowest in women and men with the shortest stature (<155 and <160 cm, respectively): hazard ratios=0.31 (95% confidence interval, 0.22-0.42) and 0.35 (95% confidence interval, 0.22-0.55), respectively. There was a graded association also in the cosibling design comparing siblings with varying degree of discordance for height (reference was the taller sibling): ≥10 cm difference between brothers hazard ratios=0.69 (95% confidence interval, 0.61-0.78) and sisters hazard ratios=0.65 (95% confidence interval, 0.52-0.80), respectively.

CONCLUSIONS

Height is an independent predictor of VTE. The use of sibling pairs reduces the likelihood that familial confounding explains the results. The findings are important for the understanding of the pathogenesis of VTE.

Joint effects of prothrombotic genotypes and body height on the risk of venous thromboembolism: the Tromsø study

Essentials Body height and prothrombotic genotypes are associated with risk of venous thromboembolism (VTE). The joint effect of prothrombotic genotypes and tall stature on VTE risk is scarcely investigated. We investigated the joint effect of prothrombotic genotypes and tall stature on VTE risk. Prothrombotic genotypes did not yield excess risk of VTE in subjects with a tall stature.

SUMMARY

Background Studies have reported synergistic effects of prothrombotic single-nucleotide polymorphisms (SNPs) and obesity on the risk of venous thromboembolism (VTE). Tall stature is associated with an increased VTE risk, but the joint effect of prothrombotic genotypes and tall stature on the VTE risk is unknown. Aims To investigate the joint effects of prothrombotic genotypes and tall stature on the VTE risk. Methods Cases with incident VTE (n = 676) and a randomly selected age-weighted subcohort (n = 1842) were sampled from the Tromsø study (cohort follow-up: 1994-2012). DNA was genotyped for rs6025 (factor V Leiden), rs1799963 (FII), rs8176719 (ABO blood group), rs2066865 (fibrinogen-γ), and rs2036914 (FIX). Age-adjusted and sex-adjusted hazard ratios (HRs) of VTE were calculated by categories of risk alleles (de Haan 5-SNP score: 0-1, 2-3, and ≥ 4) and body height (< 40th, 40th-80th and > 80th percentiles). Results The VTE risk increased by increasing category of body height, and subjects with height ≥ 178 cm had a two-fold higher VTE risk (HR 2.03; 95% confidence interval [CI] 1.51-2.73) than those with height ≤ 165 cm. The VTE risk also increased across categories of risk alleles. However, the combination of a tall stature and risk alleles, either individual SNPs or risk score, did not result in an excess VTE risk. Subjects with four or more risk alleles and height ≥ 178 cm had a two-fold (HR 2.08; 95% CI 1.24-3.52) higher VTE risk than subjects ≤ 165 cm with no risk allele or one risk allele. Conclusions In contrast to obesity, the presence of prothrombotic genotypes did not result in an excess VTE risk in subjects with a tall stature.

Do Basketball Players Have a High Risk of Pulmonary Embolism? A Scoping Review

PURPOSE

Pulmonary embolism (PE) is a serious preventable disease that requires urgent care. In recent years, there have been several reports in the media about basketball players experiencing PE. The aim of the present study was to assess whether there is a need for in-depth studies to determine whether basketball players constitute a group particularly at risk of PE and to describe some hypotheses to be investigated.

METHODS

We reviewed original articles about PE among professional and amateur basketball players in the scientific literature (PubMed) and the Internet (Google search) for the seasons 2010-2011 to 2014-2015, both of which were included. We used search strategies that included some combination of PE-related terms. Rates of PE were calculated and were compared with those obtained from other studies.

RESULTS

Of the 15 cases detected, the majority were men (66.7%), mean ages being 28.8 yr among males and 20.4 yr among females. We focused on six cases which, were detected among National Basketball Association and Asociación de Clubes de Baloncesto basketball players, resulting in an average incidence of 1.27 and 2.06 cases per 1000 players per year in the National Basketball Association and Asociación de Clubes de Baloncesto, respectively. This incidence is much higher than that observed in general population studies for the same age group.

CONCLUSIONS

Basketball players seem to have a higher risk of PE than their peers from the general population. More studies are needed to confirm these findings and identify factors predisposing them to PE to contribute to its prevention.

Body height, mobility, and risk of first and recurrent venous thrombosis

BACKGROUND

Tall people have an increased risk of a first venous thrombosis. Sedentary lifestyle has been shown to act synergistically with body height, especially during long-haul flights.

OBJECTIVE

To estimate the relation between height and risk of a first and recurrent venous thrombosis and a possible additional association with a mobile or an immobile lifestyle.

METHODS

Patients with a first venous thrombosis and control subjects were included between 1999 and 2004 (MEGA case-control study). Patients were followed for recurrence for an average time of 5.1 years (MEGA follow-up study). Odds ratios and hazard ratios (HRs) per increase of 5 cm were calculated compared with a height of 165-170 cm, separately and in combination with (im)mobility.

RESULTS

In 4464 patients who reported their height, we found an increasing risk of a first and recurrent event with height. For men, a 2.9-fold (95% confidence interval [CI] 1.9-4.4) increased risk for first venous thrombosis was found for those between 195 and 200 cm and a 3.8-fold (95% CI 1.5-9.8) higher risk for those > 200 cm compared with the reference category. For recurrence risk, the HRs were 1.7 (95% CI 0.8-3.3) and 3.7 (95% CI 1.4-10.0), respectively. For women, a 1.5-fold (95% CI 0.7-3.4) and 3-fold (95% CI 0.9-9.4) increased risk was found for those > 185 cm for first and recurrent venous thrombosis, respectively. For the tallest men and women, a slight additionally increased risk was observed for sedentary lifestyle.

CONCLUSIONS

Tall men and women have an increased risk of first and recurrent venous thrombosis, possibly higher in combination with a sedentary lifestyle.

Association between obstructive sleep apnea and pulmonary embolism

OBJECTIVES

To compare the prevalence of obstructive sleep apnea (OSA) in patients with pulmonary embolism (PE) with a sex-, age-, and body mass index (BMI)-matched, population-based control group and to assess the association between OSA and PE.

METHODS

We performed a case-control study from October 1, 2006, through November 30, 2009. We included 107 patients with PE and a control group (n=102) without PE in University Hospitals Son Espases and La Paz in Spain. Variables included in the analysis were medical history, anthropometric variables (weight, height, BMI, and neck circumference), Epworth Sleepiness Scale score, home respiratory polygraphy, basic biochemical profile and hemogram, spirometry, and physical activity.

RESULTS

The mean ± SD apnea-hypopnea index (AHI) was significantly higher in patients with PE than population controls (21.2±20.6 vs 11.5±15.9 h(-1); P<.001). The presence of an AHI greater than 5 h(-1) and hypersomnolence (Epworth Sleepiness Scale score ≥11) was more frequent in PE patients than in controls (14.0% vs 4.9%; P=.0002). A crude model analysis by several cutoffs revealed that the AHI was significantly associated with PE. After adjustment for age, sex, smoking, BMI, lung function, and all known PE risk factors, the odds ratio for PE was 3.7 (95% CI, 1.3-10.5; P=.01).

CONCLUSION

A higher prevalence of OSA was detected in patients diagnosed as having acute PE than controls. This study identified a significant and independent association between OSA and PE.