Experience with a computer-assisted anticoagulant clinic

A mainframe interfacing computer management system for the control of oral anticoagulant therapy

A unique computerized management system has been used to control the anticoagulation of over 400 patients at a large teaching hospital for the last eighteen months. The system is located on the main pathology computer which can be interfaced with the patient administration system (PAS). This enables files in the anticoagulant program to be linked with files in the PAS and files in the haematology database. This system has many advantages over a stand-alone microcomputer system and will form the basis for the next generation of computerized anticoagulant management systems.

Computer Assisted Anticoagulant Therapy

The constantly workload increase has led to the development of Computerised Decision Support Systems (CDSS) for a better management of patient care. Many clinical situations have been investigated to verify the utility of CDSS: few have demonstrated stable effects. One area where success has been reported is the field of oral anticoagulation management. CDSS system has demonstrated to be able to improve the treatment quality in comparison to manual method. In the future scenario of oral anticoagulant management CDSS will have a pivotal part, the constant increase of patients number and their pressure on thrombosis centres had led to the development of alternative models for delivery OAT: Primary care, General Practitioner, Patient self testing and self management and the use of CDSS has been central to the decentralisation process and may be useful in maintaining the efficacy and quality of anticoagulant control. GP with the aid of CDSS are able to deliver OAT as well as expert physician of Thrombosis Centre in terms of time spent by patient in therapeutic range.

External quality assessment for warfarin dosing using computerised decision support software

AIM

To establish and evaluate an external quality assessment scheme for warfarin dosing for users of a computerised decision support system, BAP-PC.

DESIGN

Analysis of 12 months of clinical data from 10 primary care centres using BAP-PC within an oral anticoagulation clinic. Data were analysed for individual centres and compared with aggregated data for all practices. Individual feedback forms were provided to participating centres.

RESULTS

A total patient population of 367 (range, 17-65/centre) was analysed. On average, patients spent 69% of time in the therapeutic range (range, 60-76%). Patients were seen on average every 27 days (range, 24-30). The average point prevalence was 86% (range, 76-100%). In total, 33 adverse events were reported (0-13/practice). Serious adverse events ranged from 0 to 1 for each practice. This translates into a serious adverse event rate of 1.6/100 patient years.

CONCLUSIONS

Practices were successful in maintaining good therapeutic international normalised ratio control, with centres achieving 60% or higher time in range. There are some doubts about the quality of data collection at a practice level because there were no reported events in half of the participating centres. The observed event rates do concur with previously reported data, however. Further cycles of the scheme are necessary to establish it as a useful research and benchmarking tool.

Management and dosing of warfarin therapy

When initiating warfarin therapy, clinicians should avoid loading doses that can raise the International Normalized Ratio (INR) excessively; instead, warfarin should be initiated with a 5-mg dose (or 2 to 4 mg in the very elderly). With a 5-mg initial dose, the INR will not rise appreciably in the first 24 hours, except in rare patients who will ultimately require a very small daily dose (0.5 to 2.0 mg). Adjusting a steady-state warfarin dose depends on the measured INR values and clinical factors: the dose does not need to be adjusted for a single INR that is slightly out of range, and most changes should alter the total weekly dose by 5% to 20%. The INR should be monitored frequently (eg, 2 to 4 times per week) immediately after initiation of warfarin; subsequently, the interval between INR tests can be lengthened gradually (up to a maximum of 4 to 6 weeks) in patients with stable INR values. Patients who have an elevated INR will need more frequent testing and may also require vitamin K1. For example, a nonbleeding patient with an INR of 9 can be given low-dose vitamin K1 (eg, 2.5 mg phytonadione, by mouth). Patients who have an excessive INR with clinically important bleeding require clotting factors (eg, fresh-frozen plasma) as well as vitamin K1.

Review of computerized decision support systems for oral anticoagulation management

Computerized decision support systems (CDSS) are available to assist clinicians in the therapeutic management of oral anticoagulation. We report the findings relating to CDSS for oral anticoagulation management of a primary-care-based systematic review which largely focused on near-patient testing. Seven papers were reviewed which covered four different systems. The methodology of these papers was generally poor, although one randomized controlled trial showed improved therapeutic control associated with computerized management compared with human performance.

New approaches to the delivery of anticoagulant services

Anticoagulant services are changing in response to the increasing demands on the service. New approaches to the delivery of the service are evolving with more local delivery of services and a shift in the service from secondary to primary care. This change has been assisted by the development of near patient testing devices and the use of computerized anticoagulant decision support systems that are increasingly used in both secondary and primary care. The evolving role of the clinical nurse/pharmacist in the provision of this service is an important development enabling more rapid discharge of patients and the provision of local delivery of service.

Introduction of computer assisted control of oral anticoagulation in general practice

The number of patients referred to hospital clinics for monitoring of oral anticoagulation continues to rise rapidly. Introduction of computer programs for the control of oral anticoagulation improves the quality of anticoagulant control in hospital clinics. This approach has now been extended to include patients managed in general practice. Results confirm that the quality of anticoagulation can also be improved in these patients. A standard approach to anticoagulation for hospital and community based patients has also facilitated the transfer of patients on warfarin from the hospital anticoagulant clinics to the community with no deterioration in the quality of anticoagulant control. As a result, the workload in the hospital anticoagulant clinic has fallen for the first time.

Prospective comparative study of computer programs used for management of warfarin

AIMS

To compare the effectiveness of three computerised systems that are currently used for assisting warfarin control in outpatients with the customary dosing method used by experienced medical staff.

METHODS

A pilot randomised study of three systems with a follow up independently randomised study of two of these was made on 186 patients receiving long term treatment or who had recently started warfarin treatment and had been discharged from hospital.

RESULTS

All three computerised systems seemed to give satisfactory control compared with the traditional dosing method. For patients receiving more intensive treatment with an assigned target range of 3.0-4.5 computerised dosage programs achieved significantly better control; the medical staff undertreated such patients almost 50% of the time.

CONCLUSION

Computer based programs can assist outpatient anticoagulant control with warfarin during both early and long term treatment. For most patients the control achieved is as good as that obtained by the customary method of dosing, by experienced clinic doctors, although the latter tend to be too conservative when dosing patients within the intense target range of 3.0 to 4.5 International Normalised Ratio (INR). The computers were significantly more successful in this higher range.