What good are quality metrics if they measure factors that hospitals can’t change? Using readmission data after PCI in hospitals in Massachusetts, researchers attempted to identify modifiable deficiencies that hospitals could target to improve performance. What they found was a wide variation in 30-day all-cause risk-standardized readmission rates (RSRRs), little of which was attributable to differences in procedural and postprocedural factors.

Publicly reported measures for hospital quality include risk-adjusted 30-day readmission rates for pneumonia, heart failure and MI. Under the Patient Protection and Affordable Care Act (PPACA), these measures will be used to financially penalize hospitals with high readmission rates in an effort to improve care and lower costs. There is pressure to expand this policy to other conditions as well.

MedPAC has pointed to PCI as having high short-term readmission rates at a cost of $350 million a year, prompting the National Quality Forum to endorse PCI RSRRs as a new measure of hospital quality. But based on evidence that there is significant variation in RSRRs after PCI, Robert W. Yeh, MD, MSc, of the cardiology division at Massachusetts General Hospital in Boston, and colleagues said an examination of factors that account for this variability was warranted.

Their analysis was published in the April issue of Circulation: Cardiovascular Interventions.

“Understanding the reasons that patients are readmitted after PCI, identifying characteristics of patients at high risk, and determining the reasons for variability among hospital readmission rates are necessary first steps in predicting the impact of such a measure and developing implementable strategies to reduce readmissions,” Yeh and colleagues wrote.

The researchers linked two datasets for their study: National Cardiovascular Data Registry (NCDR) Cath-PCI data from acute care nonfederal Massachusetts hospitals that are submitted electronically to the Massachusetts Data Analysis Center at Harvard Medical School and hospital-discharge billing data collected by the Massachusetts Division of Healthcare Finance and Policy. For their analysis, they identified 36,060 adults at 24 hospitals who had undergone PCI between Oct. 1, 2005, and Sept. 8, 2008, and survived to discharge.

The primary outcome was readmission from any cause within 30 days after discharge. For risk adjustment they included data on sociodemographics, smoking status, medical history and cardiovascular history in their regression model. They also used nested hierarchical logistic regression models to assess differences in race, insurance status and PCI and post-PCI characteristics, in an effort to explain differences in readmission rates.

They found that 12.4 percent of the patients were readmitted within 30 days of discharge. Hospital RSRRs ranged from 9.5 percent to 17.9 percent. A third of the hospitals were considered outliers, with four lower than expected and four higher than expected. Differences in race, insurance, PCI, and post-PCI factors accounted for 10.4 percent of the between-hospital variance in RSRRs.

The 10 most common diagnoses accounted for 65 percent of all readmissions, with ischemic heart disease leading the list at 24.5 percent, followed by chest and respiratory symptoms (12.3 percent), heart failure (8.5 percent), acute MI (4.8 percent), procedural complications (4.3 percent) and cardiac dysrhythmias (3.8 percent).

Readmitted patients were older, more likely to be female, nonwhite, be insured under Medicare and have a higher prevalence of most cardiovascular and noncardiovascular comorbidities. Patients who were discharged to a nursing home, uninsured, on Medicare or Medicaid or had periprocedural complications were at higher risk of readmission while statin prescription was associated with lower risk.  

“Although a number of post-PCI factors, including procedural complications and adherence to guideline-recommended medications at discharge, were found to be associated with short-term readmission, these variables explained between 10 percent and 15 percent of the variation in risk-standardized readmission rates seen among hospitals,” Yeh and colleagues wrote.

They added that their results showed procedural complications were associated with higher readmission risk, consistent with other studies. Strategies to reduce procedural complications and improve prescription of beta-blockers and statins at discharge provide effective methods for improving performance, but they said that in their analysis these factors explained only 15 percent of differences in 30-day readmission rates.

“Defining those factors that explain between-hospital differences thus becomes a critical step to ultimately improving the value of risk-standardized readmission rates as a useful and actionable quality measure,” they suggested.

The authors warned that implementing a PCI quality measure tied with financial incentives may motivate hospitals to invest resources before fully understanding the reasons for readmission and the best pathway for prevention. The measure also may inappropriately penalize hospitals and lead to protective strategies such as prolonging hospital stays unnecessarily.

“Further studies to determine the factors that explain differences in hospital readmission rates and to identify which factors are modifiable are necessary to evaluate the validity of short-term readmission after PCI as a useful quality measure,” they concluded.

The researchers cautioned that they did not have access to data on transitions of care and outpatient care that might affect readmission rates. Their study relied solely on Massachusetts data and may not be generalizable to other settings, they wrote, but because the state mandated reporting of PCI outcomes, the data covered a broad patient population.