CJASN: Billing claims could provide sensitive cardiovascular event risk measure

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The combined use of Medicare Parts A and B billing claims composes a sensitive measure of cardiovascular events in older patients after kidney transplant, according to a study published online June 18 in the Clinical Journal of the American Society of Nephrology.

Billing claims are increasingly examined beyond administrative functions as outcomes measures in observational research, according to Krista L. Lentine, MD, from the Center for Outcomes Research and Division of Nephrology, School of Medicine at Saint Louis University, and colleagues. However, they noted that few studies have described the performance of billing claims as surrogate measures of clinical events among kidney transplant recipients.

The researchers investigated the sensitivity of Medicare billing claims for clinically verified cardiovascular diagnoses (five categories) and procedures (four categories) in a novel database linking Medicare claims to EMRs of one transplant program. They identified cardiovascular events in medical records for 571 Medicare-insured transplant recipients from 1991 through 2002.

Within a claims-ascertainment period spanning of approximately 30 days of clinically recorded dates, aggregate sensitivity of single claims was higher for case definitions incorporating Medicare Parts A and B for diagnoses and procedures (90.9 percent) compared with either Part A (82.3 percent) or Part B (84.6 percent) alone, the authors wrote.

Investigators said that perfect capture of the four procedures was possible within approximately 30 days or with short claims window expansion, but sensitivity for the diagnoses trended lower with all study algorithms (91.2 percent with window up to about 90 days). However, they noted that requirement for additional confirmatory diagnosis claims did not appreciably reduce sensitivity; and sensitivity patterns were similar in the early compared with late periods of the study.

"Future collaborative and ideally prospective study is warranted to define algorithms that maximize specificity as well as sensitivity of claims from Medicare and other insurers as research measures in this population," Lentine and colleagues concluded.