Drug interactions in primary health care. A retrospective database study and its implications for the design of a computerized decision support system.
OBJECTIVE
To investigate the occurrence of potential drug interactions in primary health care from the perspective of the prescribing general practitioner.


METHODS
Retrospective database study of computer-based patient records with a query language. All drug prescriptions during a four year period were compared with concurrent or overlapping prescriptions for the same patient and these drug pairs were compared with a database of drug interactions from the Swedish drug catalogue.


METHODS
One health centre in Sweden with six general practitioners and two doctors on vocational training.


METHODS
All patients who had visited a doctor at the health centre between 1 November 1986 and 31 October 1990.


METHODS
The rate of potential interactions in relation to all drug prescriptions and the incidence rate of potential interactions for patients at risk (those receiving two or more drugs).


RESULTS
Approximately 55,000 drug prescriptions were analysed for potential drug interactions. A total of 1,074 cases of potential drug interactions were found, which corresponds to a rate of 1.9% of all drug prescriptions. The incidence rate of potential interactions was 12% for all patients at risk (those receiving two or more drugs) and 22% for elderly (> = 65 years of age) patients at risk. Major interactions were investigated concerning the extent to which the prescribing doctors were aware of the potential interactions.


CONCLUSIONS
Potential drug interactions occur at a high rate in general practice, in particular for elderly patients. Properly designed computer-based decision-support might increase the prescribing doctor's awareness of clinically significant interactions and improve the quality of drug treatment.
Linnarsson
R
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Department of Medical Informatics, Linköping University, Sweden.
D000328:Adult; D000367:Age Factors; D000368:Aged; D003658:Decision Making, Computer-Assisted; D004347:Drug Interactions; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D016347:Medical Records Systems, Computerized; D008875:Middle Aged; D010361:Patients / Q000706:statistics & numerical data*; D011320:Primary Health Care / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors