Lumbar fusion outcomes in Washington State workers' compensation.
METHODS
Retrospective population-based cohort study.


OBJECTIVE
To evaluate the influence of lumbar intervertebral fusion devices on clinical and disability outcomes among Washington State compensated workers with chronic back pain.


BACKGROUND
The efficacy of lumbar fusion for chronic low back pain remains controversial. Recent randomized controlled trials have shown results of fusion to be equivalent to those of structured exercise and cognitive intervention. Lumbar fusion rates, however, continue to increase nationally, fueled, in part, by introduction of new fusion devices, including intervertebral cages in 1996. It is not known whether these newer devices have improved outcomes, and particularly in compensated workers.


METHODS
In this population-based retrospective cohort study, we identified Washington State injured workers who underwent lumbar fusion between 1994 and 2001 from Washington State Workers' Compensation system administrative database. All the data for this study were obtained from either the claims or medical bill payment databases. Multiple logistic regression analyses were used to examine the association between the surgical technique (interbody cages and/or instrumentation) and the risk of disability, reoperation, and complications following lumbar fusion.


RESULTS
Among the 1,950 eligible subjects, fusions with cages increased from 3.6% in 1996 to 58.1% in 2001. Overall disability rate at 2 years after fusion was 63.9%, reoperation rate 22.1%, and rate for other complications 11.8%. Use of cages or instrumentation was associated with increased complication risk compared with bone-only fusions without improving disability or reoperation rates. Legal, work-related, and psychologic factors predicted worse disability. Discography and multilevel fusions predicted greater reoperation risk. Degenerative disc disease and concurrent decompression procedures predicted lower reoperation risk.


CONCLUSIONS
Use of intervertebral fusion devices rose rapidly after their introduction in 1996. This increased use was associated with an increased complication risk without improving disability or reoperation rates.
Maghout Juratli
Sham
S
Occupational Epidemiology and Health Outcomes Program, University of Washington, School of Public Health and Community Medicine, Seattle, WA 98103-9058, USA. shamj@u.washington.edu
Franklin
Gary M
GM
Mirza
Sohail K
SK
Wickizer
Thomas M
TM
Fulton-Kehoe
Deborah
D
D015331:Cohort Studies; D006233:Persons with Disabilities / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D016268:Internal Fixators / Q000009:adverse effects* / Q000706:statistics & numerical data*; D008159:Lumbar Vertebrae / Q000293:injuries* / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology; D012086:Reoperation / Q000706:statistics & numerical data; D012189:Retrospective Studies; D018570:Risk Assessment; D013123:Spinal Fusion / Q000295:instrumentation* / Q000706:statistics & numerical data; D014861:Washington / Q000453:epidemiology; D014942:Workers' Compensation / Q000706:statistics & numerical data*