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12
| 3 | 2004
Klinisk Biokemi i Norden
We have monitored patients on
oral anticoagulation for many
years at our department. From
1995 – 2003 the number of
patients increased from 250 to
600 pr year and visits for this
purpose from 2500 to 6000.
The patients were registered
on a conventional paper-based
record system with manual transferal of INR results.
The dosage and date for next visit was written in
the record and later transferred to a dosage plan,
which was given or sent to the patients.
There were several drawbacks with this system.
- The administrative burden increased with the
growing numbers of patients.
- Retrieval of data was difficult, for instance in
connection with a phone call from a patient.
- Monitoring of the quality of the treatment given
was time-consuming as well as generation of
statistics.
- Mistakes during dosage increased with the
increasing workload.
A computer-based system?
As personal computers came into common use
around 1990 we often discussed the possibility of
designing a system which could assist physicians,
laboratory technicians and secretaries in the mana-
gement of these patients.
During 1994-96 Jens Flensted Lassen worked as
a Ph.D.-student in our lab to identify the factors
which caused variations in the INR results and
consequently on the physicians decision to change
dosage.
He described the “Ping-Pong effect” caused by
the physician reacting to small changes in INR with
changes in dosage leading to INR values oscillat-
ing above and below the therapeutic interval. He
furthermore described the “critical difference” i.e.
the change in INR value, which represented a sig-
nificant change that requires an alteration in dose.
(1,2).
Development and implementation of an electronic decision
support system for oral anticoagulation
Ivan Brandslund, The Laboratory Center, Vejle County Hospital.
E-post: ibr@vs.vejleamt.dk
Figure 1.
Presentation of
patients.
