Long-term clinical outcomes and complications after surgical treatment of degenerative spinal diseases: The Effect of BMI and Smoking

2014

Purpose
Degeneration diseases of the spine cause symptoms such as pain and radiculopathy.  After exhausting non-surgical options, decompression and fusion is utilized to treat symptoms.  The pre-operative risk factors for complications and inferior outcomes in these patients are not clearly understood.  We studied the impact of 2 specific risk factors, smoking and body mass index (BMI), on the long-term clinical outcomes including complications after arthrodesis for spinal degenerative disease.

Methods
Prospectively gathered data were retrospectively reviewed from 228 patients, age 57.1 (21.2-86.3 years) who underwent open posterior spinal fusion with BMP for spinal degeneration from 2002-2011 at one spine center.  All patients had a minimum of 2 year clinical and radiographic follow-up. Fusions averaged 2.3 (range1-7) levels; 195 had TLIF, 22 had ALIF.  The BMI and smoking status of the patient were recorded. Clinical outcomes included perioperative and long-term complications, preoperative and 2 year Visual Analog Pain Scale (VAS) and Oswestry Disability Index (ODI).  Using logistic regression, the association of BMI and smoking status on outcome measures was analyzed.

Results
At an average follow-up of 5.8 years (24.1-125.6 months) complications included nonunion-9, infection-5, adjacent fractures-5 and long-term adjacent degeneration-97. Revision or extension of fusion was required in 43 (19%). The average BMI was 28.8 (16.2-43.6)) with 36 patients who were smokers.  The average preoperative VAS and ODI were 6.7 (0-10) and 52.8% (8-92%), respectively. At 2 years post-operative the average VAS and ODI were 4.1 (0-9) and 34.6 (0-78.0%), respectively.  Logistic regression found that neither BMI nor smoking were significant predictors of post-operative VAS and ODI scores.  The only significant predictors of post-operative VAS and ODI scores were preoperative VAS and ODI scores (p<0.001) and increasing age (p=0.033).  The overall complication rate was 14% in this study. Smoking and BMI had an Odds Ratio (OR) of 5.02 (95% CI 1.87-13.49) and 1.09 (95% CI 1.01-1.18) for rate of complications.  Age had an OR of 1.06 (95% CI 1.02-1.10)

Conclusion
At an average of 5 years of follow-up after PSF for spinal degeneration, one in five patients required revision or extension of their index procedure. Both smoking and BMI increased the odds of complications with smoking having a stronger predictive value.  Age was also weakly associated with increased complications.