Validation of diagnosis codes to identify side of colon in an electronic health record registry.

568Background: The anatomical side of the colon from which a tumor arises is prognostic. Real-world evidence (RWE) studies in colon cancer should include this information. Can International Classification of Diseases (ICD) codes be reliably used to determine side of tumor, and, if so, when? Should electronic health records (EHR) be reviewed to supplement? Methods: Flatiron Health maintains an EHR-derived registry for metastatic colon cancer patients (current N = 9403). A random sample of 100 patients was included in this study. Data about tumor site was compared using ICD codes versus data abstracted from unstructured documents in the EHR (e.g., surgical notes). Concordance was determined via observed agreement and Cohen’s kappa coefficient (𝜿). Accuracy of ICD codes was determined by calculating the sensitivity, specificity, and positive predictive values, and corresponding 95% confidence intervals (CI), using abstracted data as the gold standard. Results: Sampled patients had similar side of colon distr...