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Adverse events and warfarin management

 

Clinical bottom line

Different ways of delivering warfarin therapy may give different rates of adverse events like major and minor bleeding, but information is mainly from small retrospective and uncontrolled studies.


Reference

JE Ansell & R Hughes. Evolving models of warfarin management: anticoagulation clinics, patient self-monitoring, and patient self-management. American heart Journal 1996 132: 1095-1100.

Study

This paper is a lengthy editorial. It reviews warfarin adverse events in relation to management of warfarin therapy, but has no documented search strategy and few definitions to help readers. It defined coordinated anticoagulation care or management service as a specialised programme focussing predominantly on oral anticoagulant therapy. It defines routine care as that provided by a patient's own physician without systematic organisation. No definitions are given for major or minor bleed or thromboembolism.

Results

The main results are summarised in Table 1, from individual studies that were almost all retrospective analyses (though the paper gives little detail). The authors distinguish between routine and coordinated anticoagulation from studies without a control and with a control.

Table 1: Summary information

 
Number of
Event rate (percentage per year)

Type of management

Studies

Patients

Major haemorrhage

Minor haemorrhage

Thromboembolism

Uncontrolled studies
Routine anticoagulation

1

565

7.4

7.4

no data

Coordinated anticoagulation

12

11,360

4.6

27.8

4.8

Controlled studies
Routine anticoagulation

6

480

10.9

17.6

16.2

Coordinated anticoagulation

6

562

2.8

18.3

2.4

Comment

This paper was probably never intended to be a systematic review, and in many ways it fails to be helpful exactly because of those failures. We know too little about the individual studies to be content that they should be combined, and so should not make too much of the combined information.

There is a wealth of references, though. These would be useful to anyone wanting to answer the question about whether different types of delivery of care really make any difference in terms of harm from warfarin anticoagulation.