Patient self-management (PSM) of oral anticoagulation with vitamin K antagonists (VKA) is recommended for patients requiring longterm anticoagulation but some aspects are still under debate. It is not known how to identify patients with a low chance of performing well.
Data from a large survey of the International Self-Monitoring Association of Orally Anticoagulated Patients (ISMAAP) were used. The percentages of INR values within therapeutic range (TIR) were calculated as outcome variable, and various characteristics were obtained as potential predictors. Logistic regression for low anticoagulation control (TIR below 75%) was used. A prediction model was fitted by comparing receiver-operating characteristics (ROC curves).
Median age was 72 years (IQR 65 to 77 years), 30.1% were female. Indications for anticoagulation were as follows: mechanical heart valve (46.5%), atrial fibrillation (34.3%), venous thromboembolism (16.4%) and others (2.9%). The median TIR was 88.5% (IQR 76.9 to 96.2%). The patient characteristics are shown in Figure 1, predictors of anticoagulation quality in Table 1 and the final prediction model in Table 2.
Using the proposed prediction model, physicians will be able to identify patients with a low chance of performing well, considering additional teaching lessons, regular follow-up, or adjustment of therapeutic ranges. Intensifying support in this patient group will improve care in PSM patients.
Christian Schaefer1, Michael Nagler2,3, MD, PhD; Walter A. Wuillemin2,4, MD, PhD
1International Self-Monitoring Association of Oral Anticoagulated Patients (ISMAAP), Geneva, Switzerland; 2Division of Hematology and Central Hematology Laboratory, Luzerner Kantonsspital, CH-6000 Lucerne 16, Switzerland; 3Laboratory of Clinical Thrombosis and Haemostasis, and Cardiovascular Research Institute, Maastricht University Medical Center, 6229 ER Maastricht, The Netherlands; 4University of Berne, CH-3010 Berne