An administrative claims model for profiling hospital 30-day mortality rates for pneumonia patients

Abstract

Background: Outcome measures for patients hospitalized with pneumonia may complement process measures in characterizing quality of care. We sought to develop and validate a hierarchical regression model using Medicare claims data that produces hospital-level, risk-standardized 30-day mortality rates useful for public reporting for patients hospitalized with pneumonia.

Methodology/principal findings: Retrospective study of fee-for-service Medicare beneficiaries age 66 years and older with a principal discharge diagnosis of pneumonia. Candidate risk-adjustment variables included patient demographics, administrative diagnosis codes from the index hospitalization, and all inpatient and outpatient encounters from the year before admission. The model derivation cohort included 224,608 pneumonia cases admitted to 4,664 hospitals in 2000, and validation cohorts included cases from each of years 1998-2003. We compared model-derived state-level standardized mortality estimates with medical record-derived state-level standardized mortality estimates using data from the Medicare National Pneumonia Project on 50,858 patients hospitalized from 1998-2001. The final model included 31 variables and had an area under the Receiver Operating Characteristic curve of 0.72. In each administrative claims validation cohort, model fit was similar to the derivation cohort. The distribution of standardized mortality rates among hospitals ranged from 13.0% to 23.7%, with 25(th), 50(th), and 75(th) percentiles of 16.5%, 17.4%, and 18.3%, respectively. Comparing model-derived risk-standardized state mortality rates with medical record-derived estimates, the correlation coefficient was 0.86 (Standard Error = 0.032).

Conclusions/significance: An administrative claims-based model for profiling hospitals for pneumonia mortality performs consistently over several years and produces hospital estimates close to those using a medical record model.

Figure 1. Development of the derivation and validation cohorts for the pneumonia mortality models.

The administrative derivation cohort included a stratified random sample of half of the eligible pneumonia discharges for calendar year 2000. Subsequent administrative validation cohorts included the other half of eligible discharges from 2000, and all eligible discharges for calendar years 1998, 1999, and 2001–2003. The chart model derivation cohort included 50,858 eligible patients with abstracted medical record data. An additional administrative validation cohort using the claims of patients in the chart model derivation cohort was created to compare state-specific standardized mortality rates generated by the 2 models.

Figure 2. Distribution of hospital-level standardized 30-day pneumonia mortality rates.

Risk-standardized mortality rates for the 4,684 hospitals are based on the administrative claims model using data for 449,296 Medicare patients discharged during calendar year 2000.

Figure 3. Comparison of the state-level risk-standardized mortality rates generated by the medical record model and the administrative model.

Risk-standardized mortality rates were generated with both models for the 50,858 patients in the chart model derivation cohort. The correlation coefficient for rates generated by the 2 models is 0.86 (Standard Error = 0.032).