Risk factors for thrombosis in an african population

A combination of strongly associated prothrombotic single nucleotide polymorphisms could efficiently predict venous thrombosis risk

Background

Venous thrombosis (VT) is multifactorial trait that contributes to the global burden of cardiovascular diseases. Although abundant single nucleotide polymorphisms (SNPs) provoke the susceptibility of an individual to VT, research has found that the five most strongly associated SNPs, namely, rs6025 (F5 Leiden), rs2066865 (FGG), rs2036914 (F11), rs8176719 (ABO), and rs1799963 (F2), play the greatest role. Association and risk prediction models are rarely established by using merely the five strongly associated SNPs. This study aims to explore the combined VT risk predictability of the five SNPs and well-known non-genetic VT risk factors such as aging and obesity in the Hungarian population.

Methods

SNPs were genotyped in the VT group (n = 298) and control group (n = 400). Associations were established using standard genetic models. Genetic risk scores (GRS) [unweighted GRS (unGRS), weighted GRS (wGRS)] were also computed. Correspondingly, the areas under the receiver operating characteristic curves (AUCs) for genetic and non-genetic risk factors were estimated to explore their VT risk predictability in the study population.

Results

rs6025 was the most prevalent VT risk allele in the Hungarian population. Its risk allele frequency was 3.52-fold higher in the VT group than that in the control group [adjusted odds ratio (AOR) = 3.52, 95% CI: 2.50-4.95]. Using all genetic models, we found that rs6025 and rs2036914 remained significantly associated with VT risk after multiple correction testing was performed. However, rs8176719 remained statistically significant only in the multiplicative (AOR = 1.33, 95% CI: 1.07-1.64) and genotypic models (AOR = 1.77, 95% CI: 1.14-2.73). In addition, rs2066865 lost its significant association with VT risk after multiple correction testing was performed. Conversely, the prothrombin mutation (rs1799963) did not show any significant association. The AUC of Leiden mutation (rs6025) showed better discriminative accuracy than that of other SNPs (AUC = 0.62, 95% CI: 0.57-0.66). The wGRS was a better predictor for VT than the unGRS (AUC = 0.67 vs. 0.65). Furthermore, combining genetic and non-genetic VT risk factors significantly increased the AUC to 0.89 with statistically significant differences (Z = 3.924, p < 0.0001).

Conclusions

Our study revealed that the five strongly associated SNPs combined with non-genetic factors could efficiently predict individual VT risk susceptibility. The combined model was the best predictor of VT risk, so stratifying high-risk individuals based on their genetic profiling and well-known non-modifiable VT risk factors was important for the effective and efficient utilization of VT risk preventive and control measures. Furthermore, we urged further study that compares the VT risk predictability in the Hungarian population using the formerly discovered VT SNPs with the novel strongly associated VT SNPs.

Coagulation Status and Venous Thromboembolism Risk in African Americans: A Potential Risk Factor in COVID-19

Severe acute respiratory syndrome coronavirus 2 infection (COVID-19) is known to induce severe inflammation and activation of the coagulation system, resulting in a prothrombotic state. Although inflammatory conditions and organ-specific diseases have been shown to be strong determinants of morbidity and mortality in patients with COVID-19, it is unclear whether preexisting differences in coagulation impact the severity of COVID-19. African Americans have higher rates of COVID-19 infection and disease-related morbidity and mortality. Moreover, African Americans are known to be at a higher risk for thrombotic events due to both biological and socioeconomic factors. In this review, we explore whether differences in baseline coagulation status and medical management of coagulation play an important role in COVID-19 disease severity and contribute to racial disparity trends within COVID-19.

Different strategies for pharmacological thromboprophylaxis for lower-limb immobilisation after injury: systematic review and economic evaluation

BACKGROUND

Thromboprophylaxis can reduce the risk of venous thromboembolism (VTE) during lower-limb immobilisation, but it is unclear whether or not this translates into meaningful health benefit, justifies the risk of bleeding or is cost-effective. Risk assessment models (RAMs) could select higher-risk individuals for thromboprophylaxis.

OBJECTIVES

To determine the clinical effectiveness and cost-effectiveness of different strategies for providing thromboprophylaxis to people with lower-limb immobilisation caused by injury and to identify priorities for future research.

DATA SOURCES

Ten electronic databases and research registers (MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Database of Abstracts of Review of Effects, the Cochrane Central Register of Controlled Trials, Health Technology Assessment database, NHS Economic Evaluation Database, Science Citation Index Expanded, ClinicalTrials.gov and the International Clinical Trials Registry Platform) were searched from inception to May 2017, and this was supplemented by hand-searching reference lists and contacting experts in the field.

REVIEW METHODS

Systematic reviews were undertaken to determine the effectiveness of pharmacological thromboprophylaxis in lower-limb immobilisation and to identify any study of risk factors or RAMs for VTE in lower-limb immobilisation. Study quality was assessed using appropriate tools. A network meta-analysis was undertaken for each outcome in the effectiveness review and the results of risk-prediction studies were presented descriptively. A modified Delphi survey was undertaken to identify risk predictors supported by expert consensus. Decision-analytic modelling was used to estimate the incremental cost per quality-adjusted life-year (QALY) gained of different thromboprophylaxis strategies from the perspectives of the NHS and Personal Social Services.

RESULTS

Data from 6857 participants across 13 trials were included in the meta-analysis. Thromboprophylaxis with low-molecular-weight heparin reduced the risk of any VTE [odds ratio (OR) 0.52, 95% credible interval (CrI) 0.37 to 0.71], clinically detected deep-vein thrombosis (DVT) (OR 0.40, 95% CrI 0.12 to 0.99) and pulmonary embolism (PE) (OR 0.17, 95% CrI 0.01 to 0.88). Thromboprophylaxis with fondaparinux (Arixtra®, Aspen Pharma Trading Ltd, Dublin, Ireland) reduced the risk of any VTE (OR 0.13, 95% CrI 0.05 to 0.30) and clinically detected DVT (OR 0.10, 95% CrI 0.01 to 0.94), but the effect on PE was inconclusive (OR 0.47, 95% CrI 0.01 to 9.54). Estimates of the risk of major bleeding with thromboprophylaxis were inconclusive owing to the small numbers of events. Fifteen studies of risk factors were identified, but only age (ORs 1.05 to 3.48), and injury type were consistently associated with VTE. Six studies of RAMs were identified, but only two reported prognostic accuracy data for VTE, based on small numbers of patients. Expert consensus was achieved for 13 risk predictors in lower-limb immobilisation due to injury. Modelling showed that thromboprophylaxis for all is effective (0.015 QALY gain, 95% CrI 0.004 to 0.029 QALYs) with a cost-effectiveness of £13,524 per QALY, compared with thromboprophylaxis for none. If risk-based strategies are included, it is potentially more cost-effective to limit thromboprophylaxis to patients with a Leiden thrombosis risk in plaster (cast) [L-TRiP(cast)] score of ≥ 9 (£20,000 per QALY threshold) or ≥ 8 (£30,000 per QALY threshold). An optimal threshold on the L-TRiP(cast) receiver operating characteristic curve would have sensitivity of 84-89% and specificity of 46-55%.

LIMITATIONS

Estimates of RAM prognostic accuracy are based on weak evidence. People at risk of bleeding were excluded from trials and, by implication, from modelling.

CONCLUSIONS

Thromboprophylaxis for lower-limb immobilisation due to injury is clinically effective and cost-effective compared with no thromboprophylaxis. Risk-based thromboprophylaxis is potentially optimal but the prognostic accuracy of existing RAMs is uncertain.

FUTURE WORK

Research is required to determine whether or not an appropriate RAM can accurately select higher-risk patients for thromboprophylaxis.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017058688.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Risk factors for deep vein thrombosis of lower extremities in Sudanese women

Aim

In this study, we aimed to analyze the genetic and acquired risk factors for deep vein thrombosis (DVT) of the lower extremities among Sudanese women.

Methods

A total of 136 women were enrolled in the study, including 75 DVT patients and 61 healthy controls. Demographic and clinical data were collected using a specific questionnaire. Citrated blood samples of patients and controls were used for coagulation assays, and DNAs isolated from EDTA-blood samples were used for the detection of Factor V Leiden and prothrombin G20210A mutations using multiplex polymerase chain reaction-restriction fragment length polymorphism analysis.

Results

Both gene mutations were found to be absent from all 136 subjects, and therefore did not account for the incidence of DVT in Sudanese women. Of the 75 DVTs, 70 (93.3%) were localized in the left leg and 5 (6.7%) in the right leg. Additionally, 84% of the DVTs were proximal and 16% were distal. Among the 75 patients, 22 (29.33%) were postpartum, 7 (9.33%) were pregnant, and 46 (61.33%) were nonpregnant. Levels of prothrombin fragment 1+2, prothrombin time, activated partial thromboplastin time, and D-dimer were significantly higher in DVT patients than in healthy controls (P<0.0001).

Conclusion

Risk factors that most significantly affected patients in the 18–45 years age group were pregnancy and oral contraceptive usage, whereas those that most significantly affected patients in the 66–90 years age group were immobility, heart disease, and history of DVT.

[Factors of compliance with the wearing of elastic compression stockings in a Sub-Saharan population]

INTRODUCTION

Elastic venous compression is the basic treatment of chronic venous insufficiency (CVI) and deep vein thrombosis (DVT). Very little data exist in sub-Saharan Africa concerning the wearing of compression stockings.

AIM

To determine the factors of compliance with wearing elastic compression stockings.

MATERIALS AND METHODS

This retrospective cross-sectional descriptive and analytical study involved 200 consecutive patients (93 cases of DVT, 94 cases of CVI, 13 cases of DVT and CVI). Data on compliance with wearing compression stockings and the factors influencing this compliance were collected.

RESULTS

The average age was 51±15 years old (range 17 and 91 years old). The sex ratio was 1. The majority of patients (78.5%) performed their occupation in a standing position, for more than 8hours per day for 80.5%. DVT were preferentially on the left side (52.9%) and proximal (44.4%). Concerning the CVI, the predominant symptoms were class C3 (52.3%), C4 and C5 (43.9%) of the CEAP classification. Bilateral involvement was dominant (53.3%) and the large saphenous vein was the most affected (66.9%) compared with 33.1% for the small saphenous vein exclusively. The most common type of stockings prescribed was the lower mid-thighs (57%), followed by the pantyhose (30%), in classes 3 (63%) and 2 (36.5%). The majority of patients (75%) agreed to wear their stockings after prescription with a good compliance rate of 58.5% at the beginning of the prescription. At the time of the study, this rate was 11%. The optimal duration of compliance with wearing compression stockings was 6 months (64%). Over 12 months this rate fell to 7.5%. The main causes were stocking-related compression discomfort (36.7%), patient neglect (21.5%), threading difficulties (16.9%), and an unfavorable working environment (8.7%). The determining factors of compliance with wearing of stockings were living in a couple (68.4% vs 54.2, P=0.04), CVI (53% vs 38.2%, P=0.04) and C3 (39% vs 80%), C4 (37.5% vs 17%), C5 (18% vs 3%) CVI (P=0.0005).

CONCLUSION

Compliance with wearing elastic compression stockings is mediocre. The main factors of non-compliance are discomfort, threading difficulties and patient neglect.