Methods for managing the increased workload in anticoagulant clinics

Abstract

A weekly anticoagulant clinic was administered by a phlebotomist with the help of two health care assistants, and all patients were seen by the clinic doctors (a consultant haematologist and a registrar) for dosing and counselling. In 1991 a baseline audit of 152 notes and details of anticoagulant control over six months was conducted. As only half of clinic attenders spend more than half the time within therapeutic limits,4 100 patients were required to have an 80% chance of detecting a 20% change in the proportion of patients spending most of the study period within their target range. The first group (group 1) was a 1 in 2 sample of patients attending the clinic for more than six months (n=105), selected alternately from an alphabetical list. Because control of anticoagulation is more variable at the start of treatment,5 a second group (group 2) was formed from consecutive new patients (n=47). Control of anticoagulation was audited against the patients' individual international normalised ratio (INR) target ranges. We estimated the time which each patient spent within therapeutic limits during the six months by calculating the interval between INR tests and dividing it equally between INR results at the beginning and end of each interval.