After a decade in which physicians and observers focused on processes and outcomes, the pendulum is swinging back toward viewing volume as the best barometer of hospital quality.
Welcome back, Procedural Volume.
Your popularity as a way to measure hospital quality—that the more procedures a hospital or doctor does, the lower risk of complications and vice versa—has been on the wane. But now you're trending back up. Good for you.
Here's why:
- On Wednesday, U.S. News & World Report published, as part of its annual Best Hospitals report, a special new set of ratings that evaluate hospital performance in five common surgical procedures and medical conditions. The expanded report, Best Hospitals for Common Care, found that patients who receive these procedures at low-volume hospitals have a much higher risk of death or complications, while patients at higher-volume facilities have a reduced risk.
- On Tuesday, Dartmouth-Hitchcock Medical Center, The Johns Hopkins Hospital and Health System, and the University of Michigan Health System announced their "Take the Volume Pledge" program. They will restrict their 20 hospitals and surgeons from performing any of 10 procedures if they don't do a minimum amount per year. They also encourage other hospitals to adopt similar policies, perhaps as a condition for granting physician staff privilege.
- The Centers for Medicare & Medicaid Services has begun posting on a new Hospital Compare tab the number of Medicare beneficiaries who received care for any of 64 medical conditions or surgeries at various levels of complexity. The idea is that an especially fragile patient may require a hospital with experience treating a more complex case.
"There is a pendulum swing back toward paying attention to the volume/outcome story now," says John Birkmeyer, MD, a surgeon, outcomes researcher, and executive vice president for enterprise support services at Dartmouth-Hitchcock.
So procedural volume is officially back in the game. Or maybe we're just re-recognizing volume with much more appreciation for the important role it plays.
Volume has had an interesting journey since it first came on the scene in 2001.
That's when the Leapfrog Group's survey, in an effort to help employers and patients make better choices about hospital care, became the first advocacy group to include procedural volume as a proxy for quality of care.
Leapfrog scored reporting hospitals on how often they performed six procedures, setting minimum numbers for each necessary for proficiency: coronary artery bypass grafts, coronary angioplasty, carotid endarterectomy, esophageal cancer surgery, abdominal aortic aneurysm repair, and high-risk obstetrics. Later came aortic valve repairs and pancreatectomies.
Leapfrog's move, which President Leah Binder says garnered criticism at the time, was based on numerous studies published in the New England Journal of Medicine and other journals showing that procedure volume was just about the best quality measure going at the time, other than mortality, the ultimate outcome measure. Dozens of other quality measures were added in later years, diluting the impact of volume, but procedural volume persisted.
Birkmeyer, who has written many papers linking higher volume to better outcomes and advised Leapfrog in its move to use volume to guide choice of care, recalls those days as having "a huge flurry of attention to this from the lay media and professional [physician] societies. But over the next few years, volume as a measure for outcomes moved to the back burner."
That was partly because "the professional societies—the physician guilds—were successful in arguing that volume is just a proxy of quality and we should really measure outcomes and more direct measures of quality," for example infection rates or reoperation rates, "rather than getting so distracted with volume."
What followed was a new emphasis on process measures, such as timely administration of clot-busting drugs to heart attack patients, or giving surgical patients timely antibiotics, which correlate with greater success.
With the passage of the Patient Protection and Affordable Care Act in 2010, new penalty programs added readmission rates, patient experience survey scores, and infections to the equation of what determines high quality. And today, those measures are associated with adjustments to hospital pay that can represent nearly 6% of a hospital's annual reimbursement from Medicare.
Today, many of those measures are under fire as hospital officials point out bias or flaws. Counting avoidable 30-day readmission rates is controversial because it lacks an adjustment for socioeconomic status and unfairly punishes hospitals that treat the poor. Thirty-day mortality is important, but carries a low weight in the scoring formula, and may be more sensitive to patient comorbidities than the adjustment factor shows, some argue.
Last year, the Centers for Disease Control and Prevention acknowledged, and corrected this year, its measures for counting central line bloodstream and catheter-associated urinary tract infections. Previously, they were too vague and allowed too much interpretation and subjectivity, leaving hospitals to interpret what qualified and what didn't. Plus, thousands of hospitals didn't have enough cases to reach statistical significance.
Now, the CDC has clarified those infection reporting definitions. But hospital officials still argue they'll never get to zero, and what is a reasonable rate of hospital-acquired infections for different kinds of facilities remains in dispute.
So we're back to volume.
"Despite all the best intentions, consumers/patients still have a real paucity of information about comparative quality of surgeons and hospitals for elective but high-risk things," Birkmeyer says. "So the promise of better quality measures never really got there, certainly in any way that's meaningful to patients or leads to better choices."
So what is it about volume that makes it such a good measure for quality?
Ashish Jha, MD, director of the Harvard Global Health Institute, and a hospitalist at the VA Boston Healthcare System, agrees that volume is on the rebound. "But we're swinging back with a far greater sophistication of why volume is important than just 'practice makes perfect,' which is what we thought 15 years ago. It may be related more toward other components that come with larger volumes, such as more nurses per patient, better nutrition programs, or even having important equipment like a PET scanner."
Birkmeyer says Jha is "exactly right."
"It may have to do, too, with having a more coordinated team that surrounds the surgeon and is there after surgery," Birkmeyer says. "It means the scrub nurses and the anesthesiologists and other teams work well.
"And that if you're seeing a condition often enough, you're able to make good judgments about who needs surgery in the first place, and obviously making sure you do those surgeries well.
"It may be the team is good at not just avoiding complications but in rescuing patients when things start to go sour. With greater procedural volume, you become more adept in seeing when something isn't right, and taking the right steps toward pulling a patient out of the fire."
That's why for Birkmeyer and Binder—and perhaps patients—volume never really went away.