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

• Different time frames of 1 to 5 year(s)
To assess the empirical association of each definition with ”gold standard‘ diagnostic test
(here, EndoPro search), 2 ×2 contingency tables were developed (Table 1). As we were
examining disease prediction in our study with two discrete categories of —diseased“ and
—non-diseased“; it was more appropriate to assess the accuracy of our administrative
definitions by 2 ×2 tables rather than correlation coefficients [40].
Table 1. 2×2 contingency table used to determine the administrative definition
characteristics
EndoPro search
(Gold standard
test)
IBD
Non-IBD
Administrative
definition
IBD Non-IBD
True False
positive negative
False True
positive negative
Sensitivity, specificity, positive predictive value, and negative predictive value were
calculated for each definition using the corresponding 2 ×2 table. For each test
characteristic, 95% confidence intervals (CI) were calculated using exact method [41].
Two possible errors were false positives (i.e. Individuals who were considered not to
have IBD by the gold standard test (EndoPro) but fulfilled the administrative definition
for IBD) and false negatives (i.e. an IBD patient that the administrative definition failed
to identify). Depending on where the dividing line was placed one error would have been
increased and the other would have been decreased. Considering that we aimed to
identify cases of a rare disease, the percentage of FPs should have been far less than FNs.
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