The 'carry-over' effects of patient self-testing: positive effects on usual care management by an anticoagulation...

Patient self-testing (PST) of the international normalised ratio (INR) has a positive effect on anticoagulation control. This study investigated whether the benefits of PST (other than increased frequency of testing, e.g. patient education, empowerment, compliance etc.) could be 'carried-over' into usual care management after a period of home-testing has ceased.

Patients that completed a six month period of PST (as part of a randomised controlled trial) but returned to clinic management when the trial ended were included in the study. The primary outcome variable was the difference in anticoagulation control (measured using the time in therapeutic range) between the two periods. A group of patients who were managed solely by the anticoagulation clinic served as the control.

There was no significant difference in median time in therapeutic range (TTR) between the 52 patients during clinic management post-PST and the six month period of PST (75% vs 75.3%; p=0.061). Patients tested more frequently while home-testing compared with the subsequent six month period of clinic management (once every 5.6±0.7days compared with once every 23.2±7.4days; p=0.000). Patients with previous experience of PST performed significantly better than the control group of patients (n=107) that were managed solely by the anticoagulation clinic (75% vs 59.7%; p=0.009) despite less frequent monitoring of the INR (every 23.2±7.4days vs. 17.4±6.7days; p=0.000).

The improvements in anticoagulation control observed during a period of PST can be sustained when patients cease home-testing and revert back to usual care management.