Intravenous immune globulin use in Canada

Abstract

Objectives: To determine the amount of intravenous immune globulin (IVIG) used across indications in Canada and which Canadian medical specialties prescribe IVIG. To assess the proportion of IVIG that was used in appropriate off-label and labelled indications versus those deemed to be inappropriate off-label indications.

Methods: In Canada, all IVIG is distributed by the Canadian Blood System to Canadian blood banks within the hospital setting. Hospital blood banks then dispense IVIG to individual patients as it is prescribed and, as such, many institutions maintain a comprehensive database inventory on IVIG use. This study is a retrospective review of IVIG use as obtained from 10 teaching and community hospital blood bank databases in Ontario, Quebec, Alberta and British Columbia. Two of these 10 institutions were pediatric teaching hospitals whereas the remaining eight centres were adult care sites. Product usage was assessed between 1997 and 1999 in adult care sites, and 1997 and 1998 in the pediatric hospitals. The information collected included the number of grams of IVIG dispensed, the indications, the prescribing physician's specialty and the number of patients treated for a given indication, all assessed on an annual basis. A separate analysis was performed to determine the appropriateness of IVIG use where appropriateness was based on the published 1997 and 1999 Canadian Consensus Guidelines for IVIG use.

Results: IVIG was prescribed for 90 different indications, six of which are licensed in Canada. When considered as separate populations, adult and pediatric use accounted for 61 and 65 different indications, respectively. Licensed use for all known indications represented approximately 47% and 62% in adult and pediatric settings, respectively. Twenty-nine per cent of IVIG use in adult and 17% in pediatric settings was not reported and is therefore unknown. Although off-label use by definition is approximately 53% in adults and 38% in pediatrics, the majority of overall IVIG use (89% in both populations) is considered appropriate by guideline definition. Hematologists and neurologists were the most prevalent prescribers of IVIG.

Conclusions: Based on guideline definition, appropriate off-label use of IVIG is very high in Canada.