Mortality Trends for Veterans Hospitalized With Heart Failure and Pneumonia Using Claims-Based vs Clinical Risk-Adjustment Variables.

Prior studies have reported declines in mortality for patients admitted to Veterans Health Administration (VA) and non-VA hospitals using claims-based risk adjustment. These apparent mortality reductions may be influenced by changes in coding practices. To compare trends in the VA for 30-day mortality following hospitalization for heart failure (HF) and pneumonia using claims-based and clinical risk-adjustment models. This observational time-trend study analyzed admissions to a VA Medical Center with a principal diagnosis of HF, pneumonia, or sepsis/respiratory failure (RF) with a secondary diagnosis of pneumonia. Exclusion criteria included having less than 12 months of VA enrollment, being discharged alive within 24 hours, leaving against medical advice, and hospice utilization. Admission to a VA hospital from January 2009 through September 2015. The primary outcome was 30-day, all-cause mortality. All models included age and sex. Claims-based covariates included 22 (30) comorbidities for HF (pneumonia). Clinical covariates included vital signs, laboratory values, and ejection fraction. Among the 146 924 HF admissions, the mean (SD) age was 71.6 (11.4) years and 144 502 (98.4%) were men; among the 131 325 admissions for pneumonia, the mean (SD) age was 70.8 (12.3) years and 127 491 (97.1%) were men. Unadjusted 30-day mortality rates were 6.45% (HF) and 11.22% (pneumonia). Claims-based models showed an increased predicted risk of 30-day mortality over time (0.019 percentage points per quarter for HF [95% CI, 0.015 to 0.023]; 0.053 percentage points per quarter for pneumonia [95% CI, 0.043 to 0.063]). Clinical models showed declines or no change in predicted risk (-0.014 percentage points per quarter for HF [95% CI, -0.020 to -0.008]; -0.004 percentage points per quarter for pneumonia [95% CI, -0.017 to 0.008]). Claims-based risk adjustment yielded declines in 30-day mortality of 0.051 percentage points per quarter for HF (95% CI, -0.074 to -0.027) and 0.084 percentage points per quarter for pneumonia (95% CI, -0.111 to -0.056). Models adjusting for clinical covariates attenuated or eliminated these changes for HF (-0.017 percentage points per quarter; 95% CI, -0.039 to 0.006) and for pneumonia (-0.026 percentage points per quarter; 95% CI, -0.052 to 0.001). Compared with the claims-based models, the clinical models for HF and pneumonia more accurately differentiated between patients who died after 30 days and those who did not. Among HF and pneumonia hospitalizations, adjusting for clinical covariates attenuated declines in mortality rates identified using claims-based models. Assessments of temporal trends in 30-day mortality using claims-based risk adjustment should be interpreted with caution.