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Structured Approach for Evaluating Strategies for Cancer Ascertainment Using Large-Scale Electronic Health Record
Ashley Earles1, Lin Liu1, Ranier Bustamante1
1Ashley Earles, Ranier Bustamante, and Samir Gupta, Veterans Affairs (VA) San Diego Healthcare System; Lin Liu, Karen Messer, María Elena Martínez, James D. Murphy, and Samir Gupta, University of California San Diego, San Diego; Tonya Kaltenbach, San Francisco VA Medical Center; Tonya Kaltenbach, University of California San Francisco, San Francisco, CA; Pat Coke, Central Arkansas Veterans Healthcare System, Little Rock, AR; Julie Lynch and Andrew J. Gawron, VA Salt Lake City Health Care System; Andrew J. Gawron, University of Utah, Salt Lake City, UT; Christina D. Williams, Deborah A. Fisher, and Dawn T. Provenzale, Durham VA Medical Center; and Christina D. Williams, Deborah A. Fisher, and Dawn T. Provenzale, Duke University, Durham, NC.
Purpose:
Cancer ascertainment using large-scale electronic health records is a challenge. Our aim was to propose and apply a structured approach for evaluating multiple candidate approaches for cancer ascertainment using colorectal cancer (CRC) ascertainment within the US Department of Veterans Affairs (VA) as a use case.
Methods:
The proposed approach for evaluating cancer ascertainment strategies includes assessment of individual strategy performance, comparison of agreement across strategies, and review of discordant diagnoses. We applied this approach to compare three strategies for CRC ascertainment within the VA: administrative claims data consisting of International Classification of Diseases, Ninth Revision (ICD9) diagnosis codes; the VA Central Cancer Registry (VACCR); and the newly accessible Oncology Domain, consisting of cases abstracted by local cancer registrars. The study sample consisted of 1,839,043 veterans with index colonoscopy performed from 1999 to 2014. Strategy-specific performance was estimated based on manual record review of 100 candidate CRC cases and 100 colonoscopy controls. Strategies were further compared using Cohen's κ and focused review of discordant CRC diagnoses.
Results:
A total of 92,197 individuals met at least one CRC definition. All three strategies had high sensitivity and specificity for incident CRC. However, the ICD9-based strategy demonstrated poor positive predictive value (58%). VACCR and Oncology Domain had almost perfect agreement with each other (κ, 0.87) but only moderate agreement with ICD9-based diagnoses (κ, 0.51 and 0.57, respectively). Among discordant cases reviewed, 15% of ICD9-positive but VACCR- or Oncology Domain-negative cases had incident CRC.
Conclusion:
Evaluating novel strategies for identifying cancer requires a structured approach, including validation against manual record review, agreement among candidate strategies, and focused review of discordant findings. Without careful assessment of ascertainment methods, analyses may be subject to bias and limited in clinical impact.
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