Sailing Between Scylla and Charybdis: Oral Long-term Anticoagulation in Dialysis Patients

Thilo Krüger; Vincent Brandenburg; Georg Schlieper; Nikolaus Marx; Jürgen Floege

Disclosures

Nephrol Dial Transplant. 2013;28(3):534-541. 

In This Article

Atrial Fibrillation in Dialysis Patients: Risk Stratification Using Scores

In the general population, the most widely used score to identify atrial fibrillation patients with an increased risk of thromboembolic events is the CHA2DS2-VASc score, an extension of the previous CHADS2 score (see Table 2a and Table 2b). Most components of the score such as hypertension, diabetes, advanced age or congestive heart failure are highly prevalent in dialysis populations, raising the score 2 points or higher in the majority of dialysis patients with atrial fibrillation. Consequently, they should be given OAT according to the current guidelines.[9] However, the CHA2DS2-VASc score was derived from non-renal patients and may not be valid in advanced CKD. Indeed, in dialysis patients, major components of the CHADS2-VASc score such as hypertension or congestive heart failure do not predict strokes.[17]

To assess the risk of bleeding in patients on OAT, the HAS-BLED score (Table 3) is recommended by ESC guidelines.[9,26] A score of ≥3 calls for special caution when considering OAT. Again, at least two of the score components, such as hypertension and advanced age, are highly prevalent in the dialysis population and score component number three, namely CKD, is present by definition. In addition, given the common vitamin K deficiency in advanced CKD (see below), targeting a particular INR (international normalized ratio) and maintaining it, is often difficult in ESRD patients; this adds a fourth point to the HAS-BLED score and would suggest caution with OAT in the majority of dialysis patients. However, while the ESC guidelines offer strong evidence-based recommendations for the start of OAT based on the CHA2DS-VASC2 score, the HAS-BLED score does not lead to similarly strong recommendations to stop OAT. An alternative bleeding risk score, termed ATRIA, includes anaemia, severe renal diseases, age ≥75 years, prior bleeding and hypertension (Table 4a and Table 4b). It was derived from 9186 subjects, contributing 32 888 person-years of warfarin exposure, of which ~4% exhibited a GFR <30 mL/min.[27] Patients with a GFR <30 mL/min exhibited a significantly (4.3-fold) increased risk of major haemorrhages (CI 3.2–5.8). Although the score has not been externally validated in other cohorts, it is clear that even just the two criteria, anaemia and advanced CKD, would place almost every dialysis patient in the ATRIA high-risk category.

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