An ‘ongoing uncertainty’: How reliable are national CV hospital rankings?

Hospitals ranked highest for cardiology and heart surgery by the U.S. News and World Report (USNWR) boast lower 30-day mortality rates for acute MI, heart failure and coronary artery bypass grafting (CABG), according to research published in JAMA Cardiology—but those same hospitals also see similar or higher readmission rates compared with hospitals that aren't ranked at all.

“Hospital rankings that evaluate and publicly compare hospital performance for cardiovascular care have become increasingly common as part of a movement to enhance transparency in healthcare,” first author David E. Wang, MD, and colleagues wrote in JAMA. “Understanding whether USNWR top-ranked hospitals perform better than non-ranked hospitals on mortality rates and readmission measures is important given the significant influence that these rankings may have on patients and hospitals.”

Wang and his co-authors at Brigham and Women’s Hospital and Harvard Medical School said hospital rankings should guide individuals to high-quality healthcare using metrics that matter to patients, like mortality and readmission rates. The USNWR is highly regarded by physicians and patients alike, and past research has suggested top-ranked hospitals do indeed perform better than their unranked counterparts. But studies solidifying that idea are either too narrow or too old to rely on in 2018.

In a review involving 3,552 U.S. hospitals, Wang and his team assessed 30-day risk-standardized mortality rates for acute MI (AMI), heart failure and CABG. They also considered Hospital Consumer Assessment of Healthcare Providers and Systems patient satisfaction star ratings, which they pulled from CMS databases.

Compared to 3,502 hospitals unranked by the USNWR, the authors said 30-day mortality rates at the 50 top-ranked hospitals were lower for AMI (11.9 percent compared to 13.2 percent), heart failure (9.5 percent compared to 11.9 percent) and CABG (2.3 percent compared to 3.3 percent). Readmission rates were similar for AMI and CABG, differing by just a fraction of a percentage between ranked and unranked hospitals, but higher for heart failure at top-ranked hospitals.

The researchers also found patient satisfaction was higher at top-ranked hospitals.

“Although the USNWR methods have changed in recent years, top-ranked cardiology hospitals have lower mortality rates and higher patient satisfaction scores compared with non-ranked hospitals,” they reported. “This likely reflects the fact that 37.5 percent of USNWR rankings are based on raw mortality data that are obtained from the CMS, although the approach to risk adjustment is different than that of the CMS’ risk standardization."

Wang et al. said it’s possible that mortality rates are lower in ranked hospitals and readmission rates remain similar between ranked and unranked institutions because of the implementation of the Hospital Readmissions Reduction Program, which has provided healthy financial incentives for hospitals to lower overall readmission rates. The authors suggested those incentives could have resulted in better overall readmission rates across the board, while mortality rates remained disparate between hospitals.

“Readmission rates are similar for AMI and CABG at top-ranked vs. non-ranked hospitals and are higher for heart failure at top-ranked hospitals,” the team wrote. “This disconnect between mortality rates and readmission outcomes at top-ranked hospitals compared with non-ranked hospitals highlights the ongoing uncertainty as to whether readmissions are an adequate surrogate for quality of care.”