Although patient self-management (PSM) of oral anticoagulation with vitamin K antagonists is recommended for patients requiring long-term anticoagulation, important aspects are still unclear. Using data from a large international survey (n=15834; median age 72years; 301% female), we studied predictors of poor anticoagulation control (percentage of International Normalized Ratio values within therapeutic range below 75%) and developed a simple prediction model. The following variables were identified as risk factors for poor anticoagulation control and included in the final model: higher intensity of therapeutic range (odds ratio [OR] on every level 19; 95% confidence interval [CI] 18-20), long intervals between measurements (>14d; 15; 95% CI 13-17), female sex (OR 13; 95% CI 12-14), and management other than PSM (OR 14; 95% CI 12-16). At a threshold of 02 (at least one variable present), the model predicted poor anticoagulation control with a sensitivity of 853% (95% CI: 840, 864) and a specificity of 285% (276, 295). The area under the receiver operated characteristic curve was 065. Using the proposed prediction model, physicians will be able to identify patients with a low chance of performing well, considering additional training, regular follow-up, or adjustment of therapeutic ranges.
- vitamin K antagonists
- self care
- International Normalized Ratio
- anticoagulant administration
- drug monitoring