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. 2012 Sep 4;104(17):1293–1305. doi: 10.1093/jnci/djs317

Table 1.

ICD-9 code-based algorithm used to determine HF/CM from administrative data by treatment group*

Treatment group
No chemotherapy Anthracycline only Trastuzumab only Anthracycline + trastuzumab Other chemotherapy
(n=5807 women) (n=3697 women) (n=112 women) (n=442 women) (n=2442 women)
Algorithm criteria % % % % %
≥1 primary discharge diagnosis 4.2 2.1 3.6 4.1 5.3
≥3 secondary discharge diagnoses 0.5 0.2 0 0.5 0.4
≥2 outpatient diagnoses 2.8 1.7 7.1 7.0 2.5
≥3 emergency department diagnoses 0 0 0 0 0
≥2 secondary discharge + ≥1 outpatient diagnosis 0.1 0.1 0 0 0.2
None of the above (no HF/CM) 92.5 95.9 89.3 88.5 91.7

*The study population includes 12 500 women diagnosed with incident invasive breast cancer from January 1, 1999 through December 31, 2007. All women were members of one of eight Cancer Research Network (CRN) integrated health plans for 12 or more months before breast cancer diagnosis. Administrative data included ICD-9 codes for HF/CM as noted by a provider in the medical record and available in the CRN Virtual Data Warehouse (VDW; ICD-9 codes: 398.91, 402.x1, 402.x3, 404.x1, 404.x3, 422.90, 425.4, 425.9, 428.xx). Primary and secondary discharge diagnoses were indicated at the time of the patient’s release from a hospital. Other diagnoses occurred after emergency department release or an outpatient appointment. The algorithm for this study was based on previous HF claims-based algorithms (30,41), with the addition of the 425 “cardiomyopathy” codes because of the nature of cardiotoxicity. The algorithm was validated on a subset of 400 women as previously reported (31). ICD-9 = International Classification of Diseases, Ninth Revision; HF/CM = Heart failure and/or cardiomyopathy.

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