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Variation in Outcomes Across Centers After Surgery for Lumbar Stenosis and Degenerative Spondylolisthesis in the Spine Patient Outcomes Research Trial

Desai, Atman, MD*; Bekelis, Kimon, MD*; Ball, Perry A., MD*; Lurie, Jon, MD†,‡,§; Mirza, Sohail K., MD; Tosteson, Tor D., DSc; Zhao, Wenyan, MS§; Weinstein, James N., DO, MS‡,§

doi: 10.1097/BRS.0b013e318278e571
Health Services Research

Study Design. Retrospective review of a prospectively collected database.

Objective. To examine whether short- and long-term outcomes after surgery for lumbar stenosis (SPS) and degenerative spondylolisthesis (DS) vary across centers.

Summary of Background Data. Surgery has been shown to be of benefit for both SPS and DS. For both conditions, surgery often consists of laminectomy with or without fusion. Potential differences in outcomes of these overlapping procedures across various surgical centers have not yet been investigated.

Methods. Spine Patient Outcomes Research Trial cohort participants with a confirmed diagnosis of SPS or DS undergoing surgery were followed from baseline at 6 weeks, 3, 6, and 12 months, and yearly thereafter, at 13 spine clinics in 11 US states. Baseline characteristics and short- and long-term outcomes were analyzed.

Results. A total of 793 patients underwent surgery. Significant differences were found between centers with regard to patient race, body mass index, treatment preference, neurological deficit, stenosis location, severity, and number of stenotic levels. Significant differences were also found in operative duration and blood loss, the incidence of durotomy, the length of hospital stay, and wound infection. When baseline differences were adjusted for, significant differences were still seen between centers in changes in patient functional outcome (Short Form-36 bodily pain and physical function, and Oswestry Disability Index) at 1 year after surgery. In addition, the cumulative adjusted change in the Oswestry Disability Index Score at 4 years significantly differed among centers, with Short Form-36 scores trending toward significance.

Conclusion. There is a broad and statistically significant variation in short- and long-term outcomes after surgery for SPS and DS across various academic centers, when statistically significant baseline differences are adjusted for. The findings suggest that the choice of center affects outcome after these procedures, although further studies are required to investigate which center characteristics are most important.

In this retrospective study, outcome variation after surgery for spinal stenosis and degenerative spondylolisthesis among centers participating in the Spine Patient Outcomes Research Trial (SPORT) were analyzed. Significant variation, including the presence of outlier centers, was found. This suggests that the choice of center influences the outcome after these procedures, although further studies are required to ascertain which center characteristics may be most important.

*Section of Neurosurgery

Department of Medicine

Department of Orthopaedics, Dartmouth-Hitchcock Medical Center, Lebanon, NH; and

§The Dartmouth Institute for Health Policy and Clinical Practice, Hanover, NH.

Address correspondence and reprint requests to Atman Desai, MD, Dartmouth-Hitchcock Medical Center, Section of Neurosurgery, One Medical Center Dr., Lebanon NH 03756; E-mail:

Acknowledgment date: October 31, 2011. First revision date: January 12, 2012. Second revision date: August 2, 2012. Acceptance date: October 7, 2012.

The manuscript submitted does not contain information about medical device(s)/drug(s).

The National Institute of Arthritis and Musculoskeletal and Skin Diseases (U01-AR45444) and the Office of Research on Women's Health, the National Institutes of Health, the National Institute of Occupational Safety and Health, and the Centers for Disease Control and Prevention grant funds were received in support of this work.

Relevant financial activities outside the submitted work: consultancy, grant.

© 2013 Lippincott Williams & Wilkins, Inc.