Effect of setting, monitoring intensity and patient experience on anticoagulation control: a systematic review and meta-analysis of the literature

Objectives: To investigate the relationship between time spent in the recommended target International Normalised Ratio (INR) range and the setting and intensity of anticoagulant monitoring, in both treatment-experienced and treatment-naive atrial fibrillation (AF) patients receiving oral anticoagulation (OAQ therapy for the prevention of ischaemic stroke. Research design and methods: Systematic review of published studies on participants with atrial fibrillation on anticoagulation therapy. We compared frequent monitoring (well-controlled, according to a strict protocol) versus infrequent monitoring (frequency representative of routine clinical practice), specialised care versus usual care, and naive versus prior anticoagulant use. Meta-analysis was performed using a random effects model. Results: 36 studies were included, 22 (primary data) of AF patients managed in line with the consensus guidelines target INR range of 2.0-3.0, and 14 studies (secondary data) of mixed patient groups, including AF, with an INR target of 2.0-3.5. Both data sets were combined for sensitivity analysis. Pooled mean time in INR range was 59.1% (95% Cl: 55.5, 62.8%) and 64.3% (95% Cl: 60.5, 68.0%) for infrequent monitoring and frequent monitoring, respectively. Significantly more time was spent in range in specialist care settings compared to usual care: +11.3% (95% Cl: 0.1-21.7%). Naive OAC users spent less time in range 56.5% (95% Cl: 45.5-67.5%) than existing users 61.2% (95% Cl: 57.2-65.2%). All of these differences were found to be significant in the sensitivity analyses. Conclusions: INR control is variable and dependent on monitoring intensity and duration of anticoagulant therapy.