Rates, predictive factors, and adverse outcomes of fusion surgery for lumbar degenerative disorders in Ontario, Canada between 2006 and 2015: a retrospective cohort study

Background — The addition of fusion surgery to the decompression for lumbar degenerative disorders remains controversial. The purpose of this study is to compare the rate and outcome of decompression and fusion versus decompression alone.

Methods — This population-based retrospective cohort study used several linked administrative databases to identify patients who underwent spinal decompression surgery in Ontario, Canada, from 2006-2015. Patients who had previous spine surgery, concurrent lumbar disc replacement, or a diagnosis other than degenerative disc disease were excluded. Adjusted logistic regression was used to assess our outcomes.

Results — We identified 33,912 patients, of which 9,748 (28.74%) underwent fusion. Overall, fusion rates increased from 27.66% to 31.33% over the study period (p=0.025). Factors associated with fusion included: older age, female gender, ASA ≥3, prior total joint replacement, and surgery by an orthopaedic surgeon. Fusion surgery was associated with increased odds of 30 day mortality (OR 1.77, 95% CI 1.01-3.09, p=0.046), 30-day (OR 1.94, 95% CI 1.53-2.46 p<0.0001) and 90-day reoperation (OR 1.66, 95% CI 1.35 – 2.05, p<0.0001), and 30-day readmission (OR 1.23, 95% CI 1.02-1.49, p=0.027) when adjusting for confounding variables. The odds of suffering a complication after fusion and decompression surgery vs. decompression surgery alone were 4.3-fold higher (95% CI 3.78-5.09, p<0.0001).

Conclusion — As compared to decompression alone, spinal fusion for degenerative lumbar disorders is associated with increased odds of adverse outcomes. These findings highlight the need for spine surgeons to consider carefully their indications for fusion procedures in the setting of degenerative spinal disorders.