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Trends in Spine Patients Over Time

Age and Comorbidities Have Increased, While Complication Rates Have Decreased or Remained the Same

Researchers at Hospital for Special Surgery (HSS) have found that the median age of patients undergoing spine surgery has increased significantly from 2006 to 2016, with an accompanying increase in comorbidities. However, the overall rates of complications from these surgeries have either stayed the same or decreased.1 These findings were presented at the 2019 American Society of Anesthesiologists (ASA) Annual Meeting on October 19.

As the demand for spine surgeries — specifically anterior cervical discectomy and fusion (ACDF) and posterior lumbar fusion (PLF) — continues to rise, it is important to understand changes in the patient populations undergoing these procedures.

“The assumption in medicine is that as knowledge advances, clinicians and treatments get better and better, and therefore complications should decrease,” said Stavros Memtsoudis, MD, PhD, MBA, an anesthesiologist at HSS. “It’s one of those untested theories that people rarely question because they feel like it’s a logical conclusion. Studies that look into whether that’s true are really rare.”

A decade ago, Dr. Memtsoudis and colleagues conducted studies of patients who had undergone joint replacements and spine surgeries to examine whether complications had decreased between 1998 and 2008 and found that they did not. They also found that while mortality either decreased or remained stable, many other complications measured either stayed the same or increased.2,3 “We also found that the average comorbidity burden, meaning how sick a patient is when they show up for surgery, also went up,” he said. “Our conclusion at the time was, we may be getting better at identifying complications and taking care of them, as evidenced by lower mortality rates, but the fact that patients are sicker makes it more likely that complications will occur, resulting in no change overall or sometimes worsening outcomes. We decided we wanted to repeat this study 10 years later.”

As a follow-up, the researchers identified 236,856 cases of ACDF surgery and 170,238 cases of PLF surgery in the national Premier Healthcare database of HSS patients between 2006 and 2016. They examined patient and hospital characteristics, patient comorbidities and postoperative complications, including blood transfusions; cardiovascular, pulmonary, renal or wound complications; hemorrhage; stroke; sepsis; thromboembolism; delirium; inpatient falls and mortality.

The median age of patients undergoing these surgeries increased significantly from 2006 to 2016, from 51 to 57 years for ACDF and from 58 to 61 years for PLF.

Comorbidities in these patients also increased, from 61% to 76% in ACDF and from 75% to 81% in PLF. However, despite patients’ increased age and higher rates of comorbidities, overall rates of complications and blood transfusions were stable in ACDF and decreased in PLF.

“The decrease in complications may be because we’ve developed protocols specifically to prevent some of the complications, including new interventions, or that we may be better at appropriately screening patients for surgeries,” Dr. Memtsoudis explained.

However, when evaluating complications individually, acute renal failure and inpatient falls were found to have significantly increased in both ACDF and PLF patients. Hemorrhage/hematoma and wound complications also increased in ACDF. All other postoperative complication rates remained stable or declined in PLF.

“This may be because patients are getting older,” Dr. Memtsoudis said. “Not only is the population aging in general, but surgeons are also getting more and more comfortable extending certain procedures to older patients. We know that age is a risk factor for inpatient falls. If people fall, they’re also more likely to have wound complications.”

He added that as patients get sicker, they are also more likely to have conditions such as diabetes, obesity or hypertension. These comorbidities, which raise the risk of wound infections and complications, have increased.

The increase in hematoma complications may be due to the increasing potency of anticoagulant medications that clinicians use to prevent blood clots, Dr. Memtsoudis explained.

“This study encourages us to step back and try to find further answers,” he added. “We want to be sure that it’s not something that we are doing that increases these complication rates. Currently we’re looking at a study balancing the risk of hematomas and bleeding that requires transfusions with the benefits of preventing blood clots, specifically, pulmonary embolisms and deep vein thrombosis.”

Results from this work suggest that other follow-up research is needed, including identifying risk factors for infections and what causes renal failure in some patients.

“This study also allows hospital administrators to keep an eye on trends, where resources need to be allocated, and to attack the problems that need attacking,” Dr. Memtsoudis concluded.


1. Lauren A. Wilson MPH, Megan Fiasconaro MS, Jiabin Liu MD PhD, Janis Bekeris MD, Jashvant Poeran MD PhD, David H. Kim MD, Federico Girardi MD, Andrew Sama MD, Stavros G. Memtsoudis MD PhD MBA FCCP. “Trends in comorbidities and complications among patients undergoing inpatient spine surgery.” Presented at: 2019 American Society of Anesthesiologists® (ASA) Annual Meeting, October 19-23, 2019; Orlando, FL.

2. M. Kirksey, Y. L. Chiu, Y. Ma, A. G. Della Valle, L. Poultsides, P. Gerner, S. G. Memtsoudis. “Trends in in-hospital major morbidity and mortality after total joint arthroplasty: United States 1998–2008.” Anesthesia & Analgesia, 2012;115(2), 321-327.

3. M. Pumberger, Y. L. Chiu, Y. Ma, F. P. Girardi, M. Mazumdar, S. G. Memtsoudis. “National in-hospital morbidity and mortality trends after lumbar fusion surgery between 1998 and 2008.” The Journal of bone and joint surgery. British volume, 2012;94(3), 359-364.

About HSS

HSS is the world’s leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the 14th consecutive year), No. 2 in rheumatology by U.S. News & World Report (2023-2024), and the best pediatric orthopedic hospital in NY, NJ and CT by U.S. News & World Report “Best Children’s Hospitals” list (2023-2024). In a survey of medical professionals in more than 20 countries by Newsweek, HSS is ranked world #1 in orthopedics for a fourth consecutive year (2023). Founded in 1863, the Hospital has the lowest readmission rates in the nation for orthopedics, and among the lowest infection and complication rates. HSS was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center five consecutive times. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State, as well as in Florida. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. In addition, more than 200 HSS clinical investigators are working to improve patient outcomes through better ways to prevent, diagnose, and treat orthopedic, rheumatic and musculoskeletal diseases. The HSS Innovation Institute works to realize the potential of new drugs, therapeutics and devices. The HSS Education Institute is a trusted leader in advancing musculoskeletal knowledge and research for physicians, nurses, allied health professionals, academic trainees, and consumers in more than 165 countries. The institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally.