Background: Efforts to identify hospital-acquired complications from claims data by applying exclusion rules to discharge diagnosis codes exhibit low positive predictive value (PPV). The PPV improves when a variable is added to each secondary diagnosis to indicate whether the condition was “present-on-admission” (POA) or “hospital-acquired”. Such indicator variables will soon be required for Medicare reimbursement. No estimates are available, however, of the proportion of hospital-acquired complications that are missed (sensitivity) using either exclusion rules or indicator variables. We estimated sensitivity, specificity, PPV, and negative predictive value (NPV) of claims-based approaches using the Rochester Epidemiology Project (REP) venous thromboembolism (VTE) cohort as a “gold standard.”
Methods: All inpatient encounters by Olmsted County, Minnesota, residents at Mayo Clinic-affiliated hospitals 1995–1998 constituted the at-risk-population. REP-identified hospital-acquired VTE consisted of all objectively-diagnosed VTE among County residents 1995–1998, whose onset of symptoms occurred during inpatient stays at these hospitals, as confirmed by detailed review of County residents' provider-linked medical records. Claims-based approaches used billing data from these hospitals.
Results: Of 37,845 inpatient encounters, 98 had REP-identified hospital-acquired VTE; 47 (48%) were medical encounters. NPV and specificity were >99% for both claims-based approaches. Although indicator variables provided higher PPV (74%) compared with exclusion rules (35%), the sensitivity for exclusion rules was 74% compared with only 38% for indicator variables. Misclassification was greater for medical than surgical encounters.
Conclusions: Utility and accuracy of claims data for identifying hospital-acquired conditions, including POA indicator variables, requires close attention be paid by clinicians and coders to what is being recorded.
From the *Department of Health Sciences Research, Mayo Clinic College of Medicine, Rochester, Minnesota; †University of California School of Public Health, Los Angeles, California; ‡Vanderbilt University Medical Center, Nashville, Tennessee; and Departments of §Internal Medicine, and ¶Nursing, Mayo Clinic College of Medicine, Rochester, Minnesota.
Supported, in part, by grants from the Robert Wood Johnson Foundation, the National Institutes of Health (HL 66216, and AR 30582), US Public Health Service, and Mayo Clinic Foundation.
Reprints: Cynthia Leibson, PhD, Department of Health Sciences Research, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905. E-mail: email@example.com.