Audit of correction of high INR in an anticoagulation clinic

Examination of the ways in which staff in the anticoagulation clinic dealt with high International Normalized Ratio (INR) results, not dosed by the computer programme, revealed an unacceptable variation in dosage change. Our aim has been to produce a protocol for either manual use and/or transfer to the computer, which would safely correct INR above the upper limit of the therapeutic range, 4.5 to a maximum of 8.0 within 7 days. We collected a large number of results (4.095) and arranged them in four INR groups (4.6-5.0, 5.1-6.0, 6.1-7.0 and 7.1-8.0) and three dosage classes (<3, 3-8 and >8 mg) in order to analyse the effects of the regimens used. This has enabled us to construct a protocol partly empirically and partly by use of a graph correlating dosage change with reduction in the INR, which will now be tested in the clinic. This protocol will deal with all INR up to a maximum of 7.0 as we have decided to contact patients with higher results. Putting this protocol onto the computer should reduce manual dosing by 15%.