System helped classify adverse events in spine surgery patients

The 2010 version of the system was validated in a European population and pediatric patient setting.

Retrospective studies may underestimate the frequency of adverse events in patients who undergo complex spine surgery, but according to the results of a prospective consecutive cohort study, the Spine Adverse Event Severity System provided spine surgeons with a proven prospective evaluation tool to identify adverse events in their patients and the level of severity for the events.

The Spine Adverse Event Severity (SAVES) system was previously validated and found reliable in the Canadian health care setting, but never before in the setting of a European population. The SAVES system improves adverse event (AE) recognition, Sven Karstensen, BSc, said at the North American Spine Society (NASS) Annual Meeting.

Data from the study Karstensen presented which received one of the two Outstanding Paper Awards at the meeing, show it can be used for a pediatric and European patient population, he noted.

AEs and SAVES

“A retrospective analysis most likely underestimates the frequency of adverse events and the SAVES system can be used as a generalizable, prospective evaluation tool. In general, the short-term mortality is acceptable compared to other surgical procedures, but for the subgroup analysis it is necessary to identify specific risk groups,” Karstensen said.

The study was conducted at a single facility in 2013. The investigators used SAVES version 2010, and an independent observer collected all intraoperative and perioperative study data. The independent observer did not treat any patients.

The Danish health care system was the study’s setting, as it closely mirrors the Canadian system where SAVES was first confirmed as a prospective evaluation tool, Karstensen said.

Focus on infection, adverse events

The study included 679 patients who underwent complex spine surgery. All patients completed the SAVES questionnaires and were grouped according to type of admission (emergency or elective) and age. They were also placed in subgroups according to the major diagnostic groups.

There were 162 intraoperative (AEs) overall for an overall incidence rate of 20%. The postoperative AEs totaled 1,415 for an overall postoperative AE incidence rate of 77%. The rate of in-hospital mortality was 1.3%, and all mortalities occurred after emergency procedures, according to the study findings.

“Fifteen patients required revision for postoperative infections and we found there was a significantly higher rate of AE in patients older than 65 years,” Karstensen said.

Settings were similar

During his presentation, Karstensen showed a table of differences between the Canadian and Danish settings where the SAVES system was studied.

“The mean number of perioperative events in our study was 2.1 per patient compared with 2.2 in the Canadian system, which highlights the similarities between the findings. The in-hospital mortality in our facility was 1.3% with hospitalization varying from 2 to 45 days,” Karstensen said.

According to Karstensen, one major challenge with morbidity studies in spine surgery is a lack of consensus for the definitions of adverse events and complications. The present study, he said, confirms that mortality alone may not be sensitive enough to reflect the general level of morbidity.

“The role of the case mix and comorbidities needs to be investigated further, as well as the extent of long-term complications. Furthermore, the economic outcomes, related to adverse events, even the minor ones, needs to be investigated,” Karstensen said.

The investigators noted the prospective registration helped improve adverse event recognition and the study data confirmed the SAVES system can be effective when used in a European and pediatric patient setting. – by Robert Linnehan

Reference:
Karstensen S, et al. Surgical science morbidity and mortality of complex spine surgery: A prospective cohort study in 679 patients validating the Spine AdVerse Event Severity (SAVES) system in a European population. Presented at: North American Spine Society Annual Meeting; Oct. 14-17, 2015; Chicago.

For more information:

Sven Karstensen, BSc, can be reached at Spine Unit, Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, 9 Blegdamsvej, 2100 Copenhagen, Denmark; email: svenhka@gmail.com.

Disclosure: Karstensen reports he receives research support from Medtronic, Globus Medical, the Lundbeck Foundation, the Danish Research Council and the Novo Nordisk Foundation.