Adequacy of anticoagulation in patients with atrial fibrillation: effect of various parameters

BACKGROUND: Despite reported evidence of the vital importance of appropriate anticoagulation in patients with chronic atrial fibrillation for stroke prevention, this treatment modality still lags behind optimal requirements. HYPOTHESIS: Our objectives were to evaluate various doctor or patient-related factors that influence quality of control and to assess the adequacy of anticoagulation provided by physicians in the community. METHODS: In a retrospective study, International Normalized Ratio (INR) values obtained immediately on admission to hospital were considered representative of previous long-term control. RESULTS: Only 42% of the relevant 385 patient population fell within the protective anticoagulation range of INR 1.91-4.1. The respective figures for patients with poor (INR < 1.5) or suboptimal (INR 1.51-1.9) control, as well as those whose INR values risked bleeding (INR > 4.1), were 28.3, 14.1, and 15.6%. Patient involvement in treatment positively influenced quality of control. By contrast, age 70-80 years or absence of congestive heart failure negatively affected quality of anticoagulation [p = 0.07, odds ratio (OR), 1.7 (95% confidence interval. 0.94-3.08), p = 0.014, OR, 2.06 (95% confidence interval, 1.15-3.7) respectively]. The percentage of patients admitted with stroke who had been adequately anticoagulated was significantly lower than that of patients who had no stroke (21 vs. 44.4%). Adequacy of anticoagulation in patients with cardiac prosthetic valves was superior compared with the rest of the patient population (56.7 vs. 42% with optimal, and only 14.5 vs. 28.3% with poor anticoagulation, respectively), indicating that under the same conditions a better quality of treatment could be achieved. CONCLUSIONS: Adequacy of anticoagulation in patients with atrial fibrillation lags behind actual recommendations. Better control is required and achievable.