The Relationship between Medicare's Process of Care Quality Measures and Mortality
Ryan, Andrew M., Burgess, James F., Jr., Tompkins, Christopher P., Wallack, Stanley S., Inquiry
Using Medicare inpatient claims and Hospital Compare process of care quality data from the period 2004-2006, we estimate two model specifications to test for the presence of correlational and causal relationships between hospital process of care performance measures and risk-adjusted (RA) 30-day mortality for heart attack, heart failure, and pneumonia. Our analysis indicates that while Hospital Compare process performance measures are correlated with 30-day mortality for each diagnosis, after we account for unobserved heterogeneity, process of care performance is no longer associated with mortality for any diagnosis. This suggests that the relationship between hospital-level process of care performance and mortality is not causal. Implications for pay-for-performance are discussed.
Medicare spending totaled $374 billion in 2006 and is expected to grow at a rate of almost 8% over the next decade (Kaiser Family Foundation 2007). The massive outlays for Medicare and well-documented deficiencies in health care quality in the United States (Institute of Medicine [IOM] 2000, 2001; McGlynn et al. 2003) have raised pressing concerns about the value of medical care received by Medicare beneficiaries. In an attempt to address these concerns, Congress enacted legislation as part of the 2005 Deficit Reduction Act calling for hospital value-based purchasing (VBP), a combination of pay-for-performance (P4P) and public quality reporting, to be implemented for Medicare hospital care by fiscal year 2009 (U.S. Congress 2005). While this deadline was missed, a recent report by the Senate Finance Committee shows strong, continued support for VBP (U.S. Senate 2009).
A critical question is how health care quality will be assessed in VBP. Process of care performance measures, which attempt to assess whether "what is now known to be 'good' medical care has been applied" (Donabedian 1966), have been the cornerstone of Medicare's existing hospital-based P4P demonstration, the Premier Hospital Quality Incentive Demonstration (PHQID), and its public quality reporting program, Hospital Compare; they are likely to be prominent, or possibly exclusive, metrics of quality in VBP. This analysis evaluates the usefulness of process performance measures in VBP by assessing the correlational and causal associations between process of care measures and 30-day mortality, a prominent and commonly used measure of patient outcomes.
The potential relationships between hospital processes and outcomes of care may vary substantially by condition and the nature of the evidence base supporting the process measures. Since our focus is Medicare VBP, this analysis employs data that are part of the current experiments. Consequently, our study is limited to examining hospital care for acute myocardial infarction (AMI), heart failure, and pneumonia, the clinical conditions for which data are widely reported in Hospital Compare and which are part of Medicare's current pay-for-reporting program.
Quality in health care is frequently defined by process, outcome, and structure measures (Donabedian 1966), with process and outcome measures being the most common. Process of care measures are often preferred to outcome measures on the grounds that providers have greater control over their performance on these measures, and that the measures offer "actionable" information for quality improvement (Birkmeyer, Kerr, and Dimick 2006; Mant 2001). However, the attribution of "quality" to performance on process of care measures is contingent on the nature of the measures. Performance on process of care measures that exhibit minimal clinical significance or a weak causal relationship with patient health will be of little value, even as effort is expended in achieving and documenting them. Absent the causal relationship between process performance and patient outcomes, process measures are compromised as a metric of individual provider improvement and as a means of selective referral to high-quality providers, since measure responsiveness by patients would not result in better outcomes. …