Anticoagulation intensity and outcomes among patients prescribed oral anticoagulant therapy: a systematic review and meta-analysis

Abstract

O ral anticoagulant therapy is essential for the treatment and prevention of many thromboembolic disorders. Since anticoagulants can cause serious adverse events, 1-3 physicians monitor the international normalized ratios of patients taking these drugs to ensure that their ratios fall within a target range.An international normalized ratio of 2-3 is the most common target range. Results of previous studies revealed an increased risk of bleeding among patients whose ratios exceeded 4, an increased risk of stroke among patients whose ratios were 1.5-2 and a decreased risk of stroke at a ratio of 2.4. 4,5 However, the evidence supporting the range of 2-3 has some deficiencies. We sought to determine whether the risk of hemorrhagic and thromboembolic events is minimized at an international normalized ratio of 2-3 among patients taking anticoagulants. In addition, it has been observed that patients spend more time with a ratio below 2 than above 3.6,7 The impact of such systematic underanticoagulation on patient outcomes is unknown. We sought to determine the effect of under-or overanticoagulation on the risk of thromboemboli and hemorrhage. Methods Data sourcesWe searched MEDLINE (1966MEDLINE ( -2006 for potentially pertinent studies. We then modified our strategy to include EMBASE (1980EMBASE ( -2006, the Cochrane Central Register of Controlled Trials (1980Trials ( -2006 and CINAHL (1982CINAHL ( -2006 databases. We manually searched references in the Science Citation Index. Our search strategy is outlined in Appendix 1 (available at www.cmaj.ca/cgi/content/full/179/3/235/DC2). Study selection

Acompanhamento Farmacoterapêutico De Pacientes Em Uso De Varfarina: Uma Revisão Da Literatura

“…Se o INR permanecer estável o controle deve ser efetuado uma ou duas vezes por mês (BARREIRA et al, 2004). Essa monitorização é importante, pois o risco de eventos tromboembólicos aumenta quando o INR apresenta valores inferiores ao alvo terapêutico; já valores superiores indicam risco aumentado de hemorragias (OAKE et al, 2008). Para a eficácia da terapia farmacológica é fundamental o conhecimento sobre o uso dos medicamentos e a adesão ao tratamento (MANSOOR et al, 2006).…”

A higher international normalized ratio may be better for your patient

“…4 Although this is higher than the absolute risk of 4.3% per year in the 2-3 range, it is much lower than many physicians think.…”

“…The elegant and carefully performed meta-analysis by Oake and colleagues 4 in this issue of CMAJ should help these physicians to understand the serious risks of underdosing. At the same time, the study provides some reassurance that international normalized ratios that are slightly above 3 are not that dangerous.…”

Implementing Evidence-Based Guidelines: The Role of Ambulatory Care Pharmacists

“…ing and thrombosis [12][13][14]. Figure 2 (online version only) includes a sample warfarin algorithm developed by pharmacists [15].…”