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Background: Cardiotoxicity is a known complication of certain breast cancer therapies, but rates come from clinical trials with design features that limit external validity. The ability to accurately identify cardiotoxicity from administrative data would enhance safety information., Objective: To characterize the performance of clinical coding algorithms for identification of cardiac dysfunction in a cancer population., Research Design: We sampled 400 charts among 6460 women diagnosed with incident breast cancer, tumor size ≥ 2 cm or node positivity, treated within 8 US health care systems between 1999 and 2007. We abstracted medical records for clinical diagnoses of heart failure (HF) and cardiomyopathy (CM) or evidence of reduced left ventricular ejection fraction. We then assessed the performance of 3 different International Classification of Diseases, 9th Edition (ICD-9)-based algorithms., Results: The HF/CM coding algorithm designed a priori to balance performance characteristics provided a sensitivity of 62% (95% confidence interval, 40%-80%), specificity of 99% (range, 97% to 99%), positive predictive value (PPV) of 69% (range, 45% to 85%), and negative predictive value (NPV) of 98% (range, 96% to 99%). When applied only to incident HF/CM (ICD-9 codes and gold standard diagnosis both occurring after breast cancer diagnosis) in patients exposed to anthracycline and/or trastuzumab therapy, the PPV was 42% (range, 14% to 76%)., Conclusions: Claims-based algorithms have moderate sensitivity and high specificity for identifying HF/CM among patients with invasive breast cancer. As the prevalence of HF/CM among the breast cancer population is low, ICD-9 codes have high NPV but only moderate PPV. These findings suggest a significant degree of misclassification due to HF/CM overcoding versus incomplete clinical documentation of HF/CM in the medical record.

Background: Most data regarding medical care for cancer patients in the United States comes from Surveillance, Epidemiology and End Results-linked Medicare analyses of individuals aged 65 years or older and typically excludes Medicare Advantage enrollees., Objectives: To assess the accuracy of chemotherapy and hormone therapy treatment data available through the Cancer Research Network's Virtual Data Warehouse (VDW)., Research Design: Retrospective, longitudinal cohort study. Medical record-abstracted, tumor registry-indicated treatments (gold standard) were compared with VDW-indicated treatments derived from health maintenance organization pharmacy, electronic medical record, and claim-based data systems., Subjects: Enrollees aged 18 years and older diagnosed with incident breast, colorectal, lung, or prostate cancer from 2000 through 2007., Measures: Sensitivity, specificity, and positive predictive value were computed at 6 and 12 months after cancer diagnosis., Results: Approximately 45% of all cancer cases (total N=23,800) were aged 64 years or younger. Overall chemotherapy sensitivity/specificities across the 3 health plans for incident breast, colorectal, lung, and prostate cancer cases were 95%/90%, 95%/93%, 93%/93%, and 85%/77%, respectively. With the exception of prostate cancer cases, overall positive predictive value ranged from 86% to 89%. Small variations in chemotherapy data accuracy existed due to cancer site and data source, whereas greater variation existed in hormone therapy capture across sites., Conclusions: Strong concordance exists between gold standard tumor registry measures of chemotherapy receipt and Cancer Research Network VDW data. Health maintenance organization VDW data can be used for a variety of studies addressing patterns of cancer care and comparative effectiveness research that previously could only be conducted among elderly Surveillance, Epidemiology and End Results-Medicare populations.