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The Risk of Risk-Adjustment Measures for Perioperative Spine Infection After Spinal Surgery

Goode, Adam P. DPT, PT*; Cook, Chad PhD, PT, MBA; Gill, J. Brian MD, MBA; Tackett, Sean MD§; Brown, Christopher MD; Richardson, William MD

doi: 10.1097/BRS.0b013e3181e030b3
Surgery

Study Design. Cross-sectional data analysis of the Nationwide Inpatient Sample (NIS).

Objective. To develop a risk-adjustment index specific for perioperative spine infection and compare this specific index to the Deyo Comorbidity Index. Assess specific mortality and morbidity adjustments between teaching and nonteaching facilities.

Summary of Background Data. Risk-adjustment measures have been developed specifically for mortality and may not be sensitive enough to adjust for morbidity across all diagnosis.

Methods. This condition-specific index was developed by using the NIS in a two-step process to determine confounders and weighting. Crude and adjusted point estimates for the Deyo and condition-specific index were compared for routine discharge, death, length of stay, and total hospital charges and then stratified by teaching hospital status.

Results. A total of 23,846 perioperative spinal infection events occurred in the NIS database between 1988 and 2007 of 1,212,241 procedures. Twenty-three diagnoses made up this condition-specific index. Significant differences between the Deyo and the condition-specific index were seen among total charges and length of stay at nonteaching hospitals (P < 0.001) and death, length of stay, and total charges (P < 0.001) for teaching hospitals.

Conclusion. This study demonstrates several key points. One, condition-specific measures may be useful when morbidity is of question. Two, a condition-specific perioperative spine infection adjustment index appears to be more sensitive at adjusting for comorbidities. Finally, there are inherent differences in hospital disposition characteristics for perioperative spine infection across teaching and nonteaching hospitals even after adjustment.

Risk-adjustment measures may not be sensitive enough to adjust for morbidity across all diagnosis. Using the Nationwide Inpatient Sample a condition-specific index was developed to adjust for perioperative spine infection. Results indicate a condition-specific perioperative spine infection index may be more sensitive at adjusting for comorbidities. However, significant differences in hospital disposition characteristics across teaching hospital status are observed even after adjustment.

*Department of Community and Family Medicine, Duke University, Durham NC

Division of Physical Therapy, Walsh University, North Canton, OH

Division of Orthopedic Surgery, Duke University Medical Center, Durham NC

§University of Pittsburgh Medical School, Pittsburgh, PA

Address correspondence and reprint requests to Adam Goode, DPT, PT, Department of Community and Family Medicine, Duke University, Durham NC 27708; E-mail: Adam.goode@duke.edu

Acknowledgment date: August 20, 2009. First revision date: January 4, 2010. Second revision date: February 25, 2010. Accepted date: March 1, 2010.

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

Federal and Foundation funds were received in support of this work.

The primary author is supported by the NIH Loan Repayment Program, National Institute of Arthritis Musculoskeletal and Skin Diseases (1-L30-AR057661-01) and the “Agency for Health Care Research and Quality (AHRQ) K-12 Comparative Effectiveness Career Development Award grant number HS19479-01. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the AHRQ.”

The primary author, Adam Goode, has been supported by the Foundation for Physical Therapy for educational financial support during his PhD training in epidemiology at the UNC Gillings School of Global Public Health.

© 2011 Lippincott Williams & Wilkins, Inc.