Variation in diagnostic coding of patients with pneumonia and its association with hospital risk-standardized mortality rates: a cross-sectional analysis.

BACKGROUND

Most U.S. hospitals publicly report 30-day risk-standardized mortality rates for pneumonia. Rates exclude severe cases, which may be assigned a secondary diagnosis of pneumonia and a principal diagnosis of sepsis or respiratory failure. By assigning sepsis and respiratory failure codes more liberally, hospitals might improve their reported performance.

OBJECTIVE

To examine the effect of the definition of pneumonia on hospital mortality rates.

DESIGN

Cross-sectional study.

SETTING

329 U.S. hospitals.

PATIENTS

Adults hospitalized for pneumonia (as a principal diagnosis or secondary diagnosis paired with a principal diagnosis of sepsis or respiratory failure) between 2007 and 2010.

MEASUREMENTS

Proportion of patients with pneumonia coded with a principal diagnosis of sepsis or respiratory failure and risk-standardized mortality rates excluding versus including a principal diagnosis of sepsis or respiratory failure.

RESULTS

When the definition of pneumonia was limited to patients with a principal diagnosis of pneumonia, the risk-standardized mortality rate was significantly better than the mean in 4.3% of hospitals and significantly worse in 6.4%. When the definition was broadened to include patients with a principal diagnosis of sepsis or respiratory failure, this rate was better than the mean in 11.9% of hospitals and worse in 22.8% and the outlier status of 28.3% of hospitals changed. Among hospitals in the highest quintile of proportion of patients coded with a principal diagnosis of sepsis or respiratory failure, outlier status under the broader definition improved in 7.6% and worsened in 40.9%. Among those in the lowest quintile, 20.0% improved and none worsened.

LIMITATION

Only inpatient mortality was studied.

CONCLUSION

Variation in use of the principal diagnosis of sepsis or respiratory failure may bias efforts to compare hospital performance regarding pneumonia outcomes.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.