Miriam E. Tucker

April 30, 2014

BOSTON — Performing endocrine surgery on an outpatient basis did not increase the risk for 30-day hospital readmission, while several patient-related factors did, 2 new studies have found.

Investigators used data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) in an effort to identify risk factors associated with readmission following cervical endocrine surgery, such as thyroid and parathyroid procedures.

Both identified American Society of Anesthesiologists (ASA) class — a widely used grading system for preoperative health of surgical patients — of greater than 2 and renal insufficiency as independent risk factors for readmission after thyroidectomy or parathyroidectomy, along with a number of other factors.

The findings were presented here at the American Association of Endocrine Surgeons (AAES) 2014 Annual Meeting by Matthew G. Mullen, MD, of the University of Virginia, Charlottesville, and James C. Iannuzzi, MD, a surgical resident at the University of Rochester Medical Center, New York.

"I think both studies are important because it's something we're all targeting. We're trying to understand readmission, to predict readmission, and to decrease the chances of it," newly installed AAES president Gerard M. Doherty, MD, Utley Professor and chair of surgery, department of surgery, and professor of medicine, Boston University School of Medicine, Massachusetts, who was not involved in either study, told Medscape Medical News in an interview.

Outpatient Thyroid and Parathyroid Surgery "Safe"

The Hospital Readmission Reduction Program, part of the 2010 Patient Protection and Affordable Care Act, aims to reduce Medicare payments by penalizing hospitals with "excessive" readmission rates. Begun in October 2012, the program currently monitors readmissions due to congestive heart failure, pneumonia, and chronic obstructive pulmonary disease (COPD) exacerbations but will soon include surgical measures, Dr. Mullen said in his introduction.

Dr. Doherty said it was a "good sign" that the 2 studies found that outpatient surgery does not increase the risk for readmission — in fact, both showed that stays of less than 24 hours were associated with lower readmission rates than inpatient surgery.

"It means we're not sending people home prematurely and then having them come back because they weren't ready to be at home. I think that endorses outpatient thyroid and parathyroid surgery as being safe," he told Medscape Medical News.

In their study, Dr. Mullen and colleagues used the 2011 ACS NSQIP data set of 7069 elective thyroidectomies (3711) and parathyroidectomies (3358) performed at 315 university and community hospitals. The primary end point was readmission to the hospital within 30 days of discharge following the procedure: the overall readmission rate was 4.0% (4.1% for thyroidectomy, 3.8% for parathyroidectomy).

Baseline variables associated with a significantly greater 30-day readmission risk included diabetes, severe COPD, chronic hemodialysis, chronic steroid use, and perioperative weight loss. Postoperative respiratory, renal, neurologic, and cardiovascular complications were also associated with increased risk for readmission, as were surgical-site infections/wound disruptions.

Readmission Risk Factors

On multivariate analysis, variables that independently predicted 30-day readmission were: reoperation within 30 days (P < .001); ASA class 3 (odds ratio [OR], 4.3; P = .024); total dependence on functional-status test (OR, 10.2; P = .007); renal insufficiency (OR 41.2; P = .004); hemodialysis (OR 2.4; P = .005); and 10% or greater weight loss (OR 3.6; P = .02).

Of particular note, patients discharged within 24 hours had a significantly lower readmission rate (OR, 0.63; P = .006).

Dr. Mullen told Medscape Medical News that while it is difficult to assign a clear cause for this association, "it may be that patients who are discharged within 24 hours are generally healthier, with fewer comorbid conditions, and suffer fewer postoperative complications, thus leading to a lower rate of 30-day readmissions. It also may be that surgeons who routinely perform these procedures as same day or [with] observation status cases have lower rates of associated complications and subsequent readmissions."

Interestingly, 63% of the patients had stays of longer than 24 hours after surgery. "We were somewhat surprised to see that only a minority of patients were discharged within 24 hours of their surgery," he said during his presentation.

Higher 30-day readmissions were also seen after surgery for malignant rather than benign disease (11% vs. 2.6%, P < .001).

Delay Elective Surgery Until Patient Is in Optimal Condition

The results suggest, said Dr. Mullen, "that if the problems are modifiable, preoperative optimization of a patient's medical conditions, including potentially delaying elective surgery until a patient is appropriate for surgery, may help reduce postoperative readmissions."

He added, "In addition to preoperative medical optimization, early recognition of postoperative complications, and close follow-up after discharge with a patient's surgeon, primary-care physician, and/or endocrinologist is of paramount importance and may lead to a reduction in readmissions."

Some limitations of this study include the lack of data in the 2011 NSQIP on the reasons for readmission and on endocrine-surgery–specific complications such as hypocalcemia or recurrent laryngeal-nerve injury, he noted.

"Although we presumed that many postoperative readmissions are related to endocrine-surgery–specific complications, we were unable to determine that with our data set," he told Medscape Medical News.

Five Risk Factors Could Contribute to "Score"

In their study, Dr. Iannuzzi and colleagues aimed to identify risk factors for readmission and develop them into a risk score for clinical use at the time of discharge following surgery.

"Identifying high-risk patients may allow providers to implement systems aimed at addressing these patients' needs, with the goal of reducing unwarranted readmissions," he said.

They used the 2011 and 2012 NSQIP data for cervical endocrine surgical procedures, including total thyroidectomy (with and without limited lymph-node dissection), lobectomy, parathyroidectomy, and modified radical lymph node dissection (MRND), with an end point of unplanned 30-day readmissions.

The analysis involved a total of 34,046 NSQIP cases (including 33% thyroidectomy, 23% parathyroidectomy and 23% lobectomy) of which there were a total of 2.8% unplanned readmissions.

Among the various procedures, the only ones for which readmission rates varied significantly from that mean [of 2.8%] were MRND (4.6%) and lobectomy (2.1%).

From a long list of the variables associated with readmission, Dr. Iannuzzi and colleagues identified the 5 strongest independent predictors: ASA greater than 2 (OR, 1.98), renal insufficiency (OR, 2.06), thyroid malignancy (OR, 1.53), hypoalbuminemia (OR, 2.58), and length of stay greater than 1 day (OR, 2.26). All were significantly more common among those who had unplanned readmissions (P < .001).

"We aimed to utilize the fewest number of factors while maximizing the predictive ability in order to improve clinical usability," he told Medscape Medical News.

The observed remission rate held close to that predicted by the score. For example, patients with 1 risk factor had both a predicted and an observed readmission rate of 3.2%, with a 1.78-fold higher risk for readmission compared with those with no risk factors. Patients with 2 risk factors had an observed readmission rate of 5.1% compared with 5.8% predicted and a 3-fold increased risk compared with those with no risk factors.

Those with 3 risk factors had a 6-fold increased risk, and 4 risk factors, a 10-fold greater risk. No patient had all 5 risk factors, Dr. Iannuzzi noted.

Dr. Doherty told Medscape Medical News that this study was important because "it told us what things might predict readmission, so that we can come up with an expected likelihood of readmission based on [baseline] patient characteristics [and derive] an observed-to-expected ratio to know whether we're really doing the right things given our patient population."

Hypocalcemia: A Potential Issue Following Surgery

Data on the reason for readmission were available in NSQIP starting in 2012. For that year, hypocalcemia was the most common, at 33%. Several audience members expressed surprise at this, given that postoperative calcium levels are manageable.

Dr. Iannuzzi told Medscape Medical News, "This finding will inform future studies aimed at understanding how many of these could be prevented through calcium supplementation at time of discharge or avoided altogether through outpatient treatment algorithms."

Dr. Doherty commented that although "hypocalcemia shouldn't happen very often," one likely reason it topped the list is that endocrine procedures are generally safe. "There aren't many other significant complications from these procedures. We don't see a lot of wound infections, for example."

Indeed, thyroid malignancies were listed as the reason for 12% of readmissions and surgical-site infection and hematoma in just 8% each. A quarter of the reasons were simply listed as "other," and 9% were NSQIP-defined complications, including bleeding, pulmonary embolism, deep vein thrombosis, and urinary-tract infection.


Dr. Doherty, Dr. Mullen and Dr. Iannuzzi have no relevant financial relationships.

American Association of Endocrine Surgeons 2014 Annual Meeting; April 28, 2014; Boston, Massachusetts. Abstracts 16 and 17.


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