February 17, 2017

The back-surgery paradox—and why it matters

Daily Briefing

Why do so many people in Casper, Wyoming, get back surgery? The answer likely boils down to physician preferences—and helps explain why controlling health care costs is so difficult, Austin Frakt and Jonathan Skinner write for the New York Times' "The Upshot."

It is not unreasonable to believe that medical treatments become more common when they are shown to be effective and fall out of favor when they are shown not to work. But these assumptions are wrong, Frakt and Skinner write.

Why 'useless' surgeries persist

"Instead, innovations in health care diffuse unevenly across geographic regions—not unlike the spread of a contagious disease," they explain. "And even when studies show a new technology is overused, retrenchment is very slow and seemingly haphazard."

Spotlight on back surgery

For example, in 1992, back surgery among older Medicare beneficiaries was relatively uncommon. In New York and other cities, as few as 1 in 1,000 patients had the procedure. By 2006, the average rate of back surgery increased to 4.9 per 1,000 patients, although rates varied significantly by region.

The surgery had become more popular despite a dearth of evidence that it was effective. "It wasn't until 2006 that the first large randomized trial on the subject was published," Frankt and Skinner note—and the results weren't encouraging.

The study found that among about 500 patients (average age, 42) in the United States, back surgery for many conditions that lead to back pain had modest benefits. Overall, about as many patients who had surgery saying they felt better after a year as patients in a control group who did not have surgery. The number of back surgeries performed in hospitals began to decline after 2006, Frakt and Skinner write, but little information was known about the rate of such surgeries in outpatient centers.

In a recent study, researchers from Dartmouth University used both outpatient and inpatient data to calculate rates of back surgery. They found that since 2006, the rate of back surgery covered by Medicare increased by 28 percent—and there's been no decrease in regional variation. "Rates in 2014 ranged from 3 per 1,000 in the Bronx to 11.5 per 1,000 in Casper, Wyoming," Frakt and Skinner write.

So what causes the regional variation? Frakt and Skinner contend that the "best guess" comes from a separate study on cardiac treatments. According to that study, different physician preferences for the intensity of cardiac treatments were significantly correlated with overall Medicare spending—particularly when the evidence of the treatment's efficacy was ambiguous. "Patient preferences exerted almost no influence," they write.

Physician preferences may drive regional variation

While the pattern hasn't been studied for back surgery in the Untied States, Frakt and Skinner speculate physician preferences are likely behind the regional differences in rates of that procedure because other explanations don't add up.

For instance, rates of back surgery are not correlated with overall care intensity, Frakt and Skinner write, noting that certain cities with low rates of back surgery also have high rates of cardiac bypass surgery. And since Medicare provides uniform reimbursement rates (adjusted for cost of living) across the country, individual physicians should have similar financial incentives to perform surgery in every region.

It is also unlikely that medical tourism accounts for the difference, Frakt and Skinner write, as Medicare record keepers would categorize an operation based on patients' hometowns, not the state or city to which they traveled for care. Regional differences in health also aren't likely to explain the difference in surgery rates, Frakt and Skinner write, noting that both New Englanders and residents in the Northern Plains states have jobs involving hard physical labor but sharply different rates of back surgery.

Moreover, a separate study found that patient preferences didn't explain variation in back surgery among several small regions in Ontario, Canada. Rather, it was physician beliefs about the benefits of the procedure that was associated with the differing rates, according to the study.

How to respond

Frakt and Skinner say there are several strategies that could help bring rates of the surgery down. For instance, providing patients with unbiased information about the procedure could help them make more informed treatment choices. "But the concern remains that for people in intense pain, when the doctor says that 'I get good results with surgery, and my patients generally feel much better,' the back surgery option, with little out-of-pocket cost, will be hard to resist," Frankt and Skinner write.

Hospitals and insurance companies can also audit outlier physicians more aggressively, as some have done recently, Frankt and Skinner write. And some employers—such as Walmart—steer patients to high-quality spine centers with financial incentives to reduce unnecessary procedures.

Frakt and Skinner say the back surgery paradox is a reminder of how difficult it is to control health care costs. "It seems just as important, though, not to let more waste creep in as it did with back surgery," they conclude. "Once it spreads widely, it's very hard to undo" (Frakt/Skinner, "The Upshot," New York Times, 2/13).

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