Efficacy of a joint didactic intervention using the Junta De Andalucía School for Patients method to control prothrombin time in patients taking anticoagulants: protocol for a randomized controlled trial

BACKGROUND: Oral anticoagulant drugs represent an essential tool in the prevention of thromboembolic events. The ones in widespread use are vitamin K antagonists, whose plasma level is monitored by measuring prothrombin time using the international normalized ratio. If its values are out of the recommended range, the patient will have a higher risk of suffering from thromboembolic or hemorrhagic complications. Previous research has shown that approximately 33% of patients keep having values at an inappropriate level. The purpose of the proposed study is to improve the international normalized ratio control results by a joint didactic intervention based on the Junta de Andalucía School for Patients method that will be implemented by anticoagulated patients themselves. METHODS: A randomized controlled trial will be undertaken at primary care centers from one healthcare area in Málaga (Andalusia, Spain). Study population: patients participating in an oral anticoagulant therapy program of vitamin K antagonists. First step: identification of patients in the oral anticoagulation therapy program with international normalized ratio control of the therapeutic level at 65% or less over total time. Second step: patients with international normalized ratio (INR) control figures under 2 or above 3 will be assigned to two different groups: Group 1 or joint intervention group: patients will be instructed in the joint didactic “from peer to peer,” by a previously trained and expert anticoagulant patient. Group 2 or control group: the control group will receive the usual clinical practice. They will be evaluated by nurses about once a month, except for cases in which their INR figures are under 2 or above 3, and those patients will be evaluated more frequently. A total of 312 individuals will be required (156 in each group) to detect differences in INR figures equal to or higher than 15% between the groups. Study variables: time on therapeutic levels before and after the intervention; sociodemographic variables; vital signs; the existence of cardiovascular risk factors or accompanying diseases in the clinical records; laboratory test including complete blood counts, bleeding time, and prothrombin time or partial thromboplastin time; and blood chemistry, other prescribed drugs, and social support. A quasi-experimental analytic study with before-after statistical analysis of the intervention will be conducted. Linear regression models will be applied for the main variable results (international normalized ratio value, time on therapeutic level) inputting sociodemographic variables, accompanying diseases, and social support. TRIAL REGISTRATION: ClinicalTrials.gov NCT03647254. Registered on 27 August 2018