Surgeons Performing Over 25 Thyroidectomies/Year Get Best Outcomes

Miriam E Tucker

March 22, 2016

A patient undergoing total thyroidectomy is far more likely to experience complications if the surgeon performs fewer than 26 such procedures a year, a new analysis finds.

Previous studies have documented associations between higher surgeon volume and better outcomes for several types of operations, including total thyroidectomy.

However, this retrospective review of hospital discharge data involving close to 17,000 patients undergoing total thyroidectomy by nearly 5000 surgeons is the first to identify an actual numeric threshold that patients and referring physicians can use as a guide for that procedure, senior investigator Julie A Sosa, MD, professor of surgery and medicine and chief of the section of endocrine surgery at Duke University, Durham, North Carolina, told Medscape Medical News.

"It's been known that the more procedures a surgeon does on average, the better their patients' outcomes will be. What's novel here in thyroidectomy is now we've identified what appears to be a cut point for a minimum volume threshold, where surgeon volume under that threshold is associated with a significant increase in complications and volumes above that threshold associated with improvement in complications," she explained.

The study also revealed that most patients underwent total thyroidectomy by surgeons performing fewer than 26 procedures a year and that half of the surgeons in the review averaged just one total thyroidectomy a year.

The results are published online March 14 in the Annals of Surgery by Mohamed Abdelgadir Adam, MD, of Duke University Medical Center, and colleagues.

Calls for Minimum Volume Standards

To address this problem in surgery overall, the Leapfrog Group, a consortium of large public and private healthcare purchasers, has promoted volume thresholds for about 10 common surgical procedures and has led volume-based referral initiatives.

And recently, three major US health systems have pledged to impose minimum-volume standards within their organization for certain procedures and have called upon other institutions to do the same.

The American College of Surgeons (ACS) has convened a working group to examine all the available evidence for volume thresholds and will issue a statement later this year.

"The issue of volume and outcomes is being examined in several areas. The college is working to create some principles that would apply broadly to a number of operations," ACS executive director David B Hoyt, MD, told Medscape Medical News.

Safety Threshold for Thyroidectomy Key for This Common Procedure

Defining a safety threshold for total thyroidectomy is of particular importance, Dr Sosa said, because it's becoming such a common procedure. Over two-thirds of Americans are believed to have thyroid nodules, and their increasing detection has led to more thyroid-cancer diagnoses.

The number of total thyroidectomies rose by more than 30% between 2006 and 2011, with approximately 130,000 now performed in the United States annually.

"There's no reason to think that's changing or flattening. We're discovering more and more nodules, and thyroid cancer is one of the fastest-growing cancers in the US," she noted.

Add to that, with total thyroidectomy, "the structures at risk are extraordinarily small…such that there's very little margin for error. While few people die of this operation, the quality-of-life implications of surgery injury and complication can be profound….If you're rendered hypoparathyroid or hoarse, you will be that way for decades."

Taken together, she said, "The implications of this volume threshold have a new dimension both in their impact not only on individual patient's lives but on a national level."

Potential ways of addressing the overall surgical-volume issue include surgical "coaching," incentivizing more surgical specialists to practice in wider geographical areas, and concentrating procedures within institutions so that only a small number of surgeons perform specific procedures.

"I think the solution to this issue is multifaceted.…This will require high-level input from physicians, patients, payers, and policy makers," Dr Sosa said.

Defining a Threshold

In their study, the Duke investigators reviewed hospital discharge data for patients undergoing total thyroidectomy between 1998 and 2009 in the Health Care Utilization Project National Inpatient Sample, which represents a sample of about 20% of inpatient discharges across the United States.

A total of 16,954 patients who underwent total thyroidectomy by 4627 surgeons met inclusion criteria. Thyroid cancer was the indication in nearly half (47%). (Thyroid lobectomies were not included because the data linking outcomes to surgeon volume are not as strong.)

The median annual surgeon volume was seven cases, ranging from one to 157. Overall, 6% of the patients experienced at least one complication after the surgery, with 2% experiencing hypoparathyroidism and/or a recurrent laryngeal nerve injury.

After adjustment for a variety of patient demographic and clinic-pathologic factors and hospital type and volume, increasing annual surgeon procedural volume was significantly associated with a decreasing likelihood of the patient experiencing a postoperative complication (P < .001).

Using a multivariate logistic regression model, the authors found that the inverse relationship between number of total thyroidectomies performed by a surgeon and the odds of complications continued up to 26 cases per year, after which there was no significant association. Results were similar with the analysis restricted to just the thyroid-cancer patients.

In subsequent analyses, surgeons who performed more than 25 total thyroidectomies a year were considered "high volume" and those doing 25 or fewer "low volume."

Compared with patients in the high-volume surgeon group, those in the low-volume surgeon group were more likely to be nonwhite, uninsured, and treated at nonteaching hospitals and in rural areas (all P < .0001).

The majority of patients (81%) underwent total thyroidectomy by low-volume surgeons, with half of the surgeons (51%) performing an average of just one case of total thyroidectomy per year.

Patients undergoing total thyroidectomy by low- vs high-volume surgeons were more likely to experience endocrine-related complications (2.3% vs 1.6%, P = .01), bleeding (1.6% vs 1.0%, P = .006), respiratory complications (1.3% vs 0.6%, P = .0002), or any complication (6.4% vs 4.1%, P < .0001).

And hospital length of stay was significantly longer for patients who underwent surgery by low-volume surgeons compared with those who had surgery by high-volume surgeons, with a median of 2 vs 1 day (P < .0001). Costs for surgical care of patients in the low-volume surgeon group were significantly higher, by a median $559 (about 10% of the total) per patient (P < .0001).

Quantifying the Risks and Moving Forward

The odds ratio for patient complications for low- vs high-volume surgeons was 1.51 (P= .002), and there was a 12% difference in length of hospital stay (P = .006).

Compared with patients of a high-volume surgeon, patients of low-volume surgeons had an 87% increase in the odds of having a complication if the surgeon performed one case per year, 68% for two to five cases/year, 42% for six to 10 cases/year, 22% for 11 to 15 cases/year, 10% for 16 to 20 cases/year, and 3% for 21 to 25 cases/year.

Dr Hoyt noted that while these new data are informative, the optimal methodology for making determinations about surgical thresholds has not yet been identified.

"We're trying to find how best to measure this kind of thing….It will continue to be studied."

Indeed, Dr Sosa told Medscape Medical News, "I think this study really should serve as a starting point for what I think will quickly become very challenging conversations and potentially contentious debate. I think it's a very important debate."

Of course, she noted, it's unrealistic to expect that everyone who undergoes total thyroidectomy in the United States will have it done by high-volume surgeons, at least in the short term, "because the sad fact is that there aren't enough such surgeons in the US and they're not regionally distributed in such a way that all patients can access them."

But, she said, institutions should begin to explore ways in which that access can be increased. "These are frank conversations we [need to] have within the medical and surgical community."

Dr Sosa is a member of the data monitoring committee of the Medullary Thyroid Cancer Registry, supported through UBC by Novo Nordisk, GlaxoSmithKline, AstraZeneca, and Eli Lilly. The coauthors and Dr Hoyt have no relevant financial relationships.

Ann Surg. Published online March 14, 2016. Abstract

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