Is it too safe to prescribe VKA for our old patients ?
By Admin
0 Comments
Is it too safe to prescribe VKA for our old patients ?
Vitamin K antagonists (VKA) are widely prescribed for the prevention and treatment of romboembolic pathologies. These agents, exert their eect by preventing the posttranslational gamma-carboxylation of vitamin K-dependent coagulation factors, ey oers too, a lot of advantages such as lack of dependence on renal clearance, availability of laboratory monitoring, reversibility, and low cost. That’s why the VKA will continue to be used for some time despite the disponibility of new oral anticiagulant.
Unfortunately, the most common adverse event experienced by patients receiving anticoagulant therapy is bleeding which limit its use substantially. ese events range from minor bleeds to life-threatening major bleeds.[1] Meta analysis have showen that the rate of bleeding change with the indication of VKA. The rate of major bleeding is from 1.4% to 3.4% per year in atrial brillation, 1.69% to 1.80% in thromboembolic venous and from 0.3% to 8.3% per patientyear for patient with prothetic valves. [2, 3, 4] In emergency departement, warfarine was identied as the most commonly drug associated with adverse events.
Several consensus guidelines have proposed the use of risk stratication models to assist physicians with the evaluation of a patient’s risk of bleeding.
Ghazali and al. treated the predictive factors of mortality among patients with vitamin K overdose. For the inclusion, the authors used Frensh guidelines published in 2008 by the Haute Autorité de santé (HAS) concerning the management of an excessively elevated INR ratio. As a risk factor of bleeding, age has been debated in several studies. Hutten et al. reported that the incidence of bleeding was higher among old patients over 60 years of age compared to patients≤60 years of age [5]. Additional prospective studies support age as a risk factor of bleeding. Ghazali nd that the rate of major bleeding was associated to patients’age over 75 years. So some views consider that advanced age should limit the prescription of VKA, while in others studies, despite all the risk factors, old age does not constitute a limit for prescription. [6] e second risk factor supported by Ghazali and coll. was anemia. The SCORE study demonstrate that only anemia wash strongly associated with risk of major bleeding. This nding hash been validate in many algorithms in recent reports. The impact of anemia was explain by the comorbidities and vulnerability of the patient, which plays a role in rheology with regards to platelet redistribution, and may lead to the alteration of primary coagulation pathways. The second raison was that anaemia reflects the existence of a predisposing lesion inwhich risk of bleeding is exacerbated by the anticoagulant regimen.
In summary, accordingly to Ghazali and many other studies, the high risk of fatal bleeding in patients under VKA are mainly the old age and anemia. Others conditions must be onssidered also like intensity of anticoagulation therapy, comorbid conditions,and drug interactions. [8] This study has unless potential limitations that need to be addressed.
First, the large majority of international studies, deal with patients with major bleeding or with asymptomatic patients under oral anticoagulation therapy with dierent evolution. Moreover, the follow-up of patient should be more specic and the correlation between mortality and VKA overdose seems biased. Finaly, the small number of cases in each analysis, limits the power of the statistical analysis. Although, these data seem interesting to predict the risk bleeding in patient with VKA in Tunisian context.
Is it too safe to prescribe VKA for our old patients ?