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16-04-2012 | Legal medicine | Article

Off-label prescribing ‘common’


Free abstract

MedWire News: Off-label prescribing is common but variable in the primary care setting, according to Canadian research published in the Archives of Internal Medicine.

"Off-label prescribing, the use of drugs for indications that have not received regulatory approval is common, occurring with up to 21% of prescribed drugs," write Tewodros Eguale (McGill University, Montreal, Canada) and colleagues. "Although the absence of regulatory approval for a treatment indication does not mean a drug is harmful in that circumstance, off-label use is suspected to be an important determinant of preventable adverse drug events."

In a study of the electronic health record network in Quebec, Canada, which involved 253,347 electronic prescriptions for 50,823 patients issued by 113 primary care physicians, the researchers found an off-label prescription prevalence of 11%. However, they also found that this varied with medication, patient, and physician characteristics.

Of the off-label prescriptions identified, 79.0% lacked strong supporting scientific evidence, report Eguale and team. The highest proportion of off-label prescribing was associated with central nervous system medications (26.3%), including anticonvulsants (66.6%), antipsychotics (43.8%), and antidepressants (33.4%), followed by anti-infective medications (17.1%), and ear-nose-throat medications (15.2%).

The researchers found that drugs with three or four approved indications were associated with less off-label use than drugs that had one or two (6.7 vs 15.7%, respectively). Likewise, drugs approved after 1995 were associated with less off-label use than those approved before 1981 (8.0 vs 17.0%).

Patients who had a Charlson Comorbidity Index of 1 or higher were found to have a lower off-label use than patients with an index of 0 (9.6 vs 11.0%). The researchers noted that the prevalence of off-label use was also influenced by the extent to which the prescribing physician uses scientific evidence to make clinical decisions, as opposed to using their clinical experience or the views of opinion leaders. Assessment using the Evidence-Practicality-Conformity questionnaire showed that physicians with a preference for evidence-based medicine had a decreased likelihood of prescribing off-label.

Eguale and co-authors conclude: "Electronic health records can be used to document treatment indication at the time of prescribing and may pave the way for enhanced postmarketing evaluation of drugs if linked to treatment outcomes."

In an accompanying editorial, Patrick O'Malley (Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA) writes that off-label prescribing "indicates that there are major gaps in our ability to monitor the appropriateness of medication use and in the evidence required to guide the use of medications in real-world settings… we need to do a better job of tracking medications by diagnosis and by appropriateness."

By Chloe McIvor

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