Importance: 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.
Objective: 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.
Design, setting, and participants: 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.
Exposures: Admission to a VA hospital from January 2009 through September 2015.
Main outcomes and measures: 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.
Results: 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.
Conclusions and relevance: 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.