Use of pharmaceuticals by inflammatory bowel disease patients: a population-based study

In 1996 we created the population-based University of Manitoba Inflammatory Bowel Disease (IBD) Database. In 1994, Manitoba Health established the Drug Program Information Network (DPIN), which identified all ambulatory prescription drugs dispensed to each individual resident of the province. All residents have a personal health identification number, and use of this number allowed linkage of the IBD database with the DPIN database. Our aim was to use the linkage of these databases to describe prescription drug use by patients with IBD in Manitoba in 1997.

We analyzed all prescriptions and costs for fiscal year 1997, and stratified our analysis by age, sex, urban versus nonurban residence, income, and disease (Crohn's disease vs ulcerative colitis). We also extracted all subjects diagnosed with IBD in 1984-1987 and those diagnosed in 1994-97 and compared any differences in prescribing patterns in 1997 for these two cohorts.

A total of 87.5% of IBD subjects received prescriptions in 1997. There was a direct, significant relationship between increasing age and number of different prescriptions per IBD drug user and total prescription costs per IBD drug user (in adults only), particularly for alimentary drugs. Female patients used a greater number of different prescriptions, but there was no difference between sexes in costs per user. Only 7.8% of patients used immunomodulatory drugs, but these accounted for the greatest cost ($1404) per user. Patients whose disease was diagnosed in 1994-1997 were significantly more likely to be prescribed oral or rectal 5-aminosalicylic acid and steroids than were those whose disease was diagnosed in 1984-1987. In addition, prescriptions for rectal 5-aminosalicylic acid were significantly increased in those patients whose diagnoses were made later over those whose diagnoses were made earlier. Male patients and Crohn's disease patients were more likely to use oral steroids and immunomodulatory medications. Based on the decade of diagnosis, there was no difference in prescribing patterns for immunomodulatory medications.

The linkage of the University of Manitoba IBD Database and the Manitoba DPIN Database allowed a description of patterns of prescription use in a population-based sample of IBD patients. Among the important findings are the lack of effect of gender and urban residence on prescription use in IBD patients; however the decade of diagnosis did affect prescribing patterns. Furthermore, only 7.8% overall receive immunomodulatory medications, but this was independent of the decade of diagnosis.