Development of an ICD Coding Definition for Inflammatory Bowel ...

5.2 Linkage with the registry
A data file with the necessary variables (refer to section 4.4) was developed for the
EndoPro procedures (i.e. 23,527 colonoscopies for 21,193 patients). As two or more of
the four linkage variables (i.e. first and last name, date of birth, and gender) were missing
in some procedure records; they were removed from the linkage process (i.e. 4.5% of the
procedures). 17,699 subjects were successfully assigned a valid PHN in the Calgary
Health Region registry (83.5%). Of 17,699 subjects, 16,717 (94.45%) were tagged as
active in the registry in fiscal year 2003/04.
5.3 Classification of the subjects
Based on the criteria presented in section 4.5 , we classified each patient (i.e. each PHN)
into one of the following categories:
• Definite IBD n = 1,353
• Possible IBD n = 840
• Non-IBD n = 15,506
Of 15,506 non-IBD subjects, 5,204 underwent colonoscopy for colorectal cancer
screening (33.6%).
5.4 Linkage to the Calgary Health Region administrative data
Using the PHNs, health service records of our patients were traced in IP, PC and ACCS
databases.
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