BMI is a risk factor for adjacent segment disease in lumbar fusion patients

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A study published ahead-of-print by the journal Neurosurgery has found that increased body mass index (BMI) is a risk factor for adjacent segment disease in patients undergoing lumbar fusion for degenerative spine diseases.

The authors, led by Chien-Yu Ou, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan, noted that although adjacent segment disease is an important complication after fusion of degenerative lumbar spines, the role of BMI in adjacent segment disease “has been addressed less”.

For the retrospective study, the team enrolled 190 patients undergoing lumbar fusion surgery to treat degeneration, documenting BMI at admission. Adjacent segment disease was defined by integration of the clinical presentations and radiographic criteria based on the morphology of the dural sac on magnetic resonance images.

Ou and colleagues write: “Adjacent segment disease was identified in 13 of the 190 patients (6.8%). The interval between surgery and diagnosis as adjacent segment disease ranged from 21 to 66 months. Five of the 13 patients required subsequent surgical intervention for clinically relevant adjacent segment disease. In the logistic regression model, BMI was a risk factor for adjacent segment disease after lumbar fusion for degenerative spine diseases (odds ratio 1.68; 95% confidence interval, 1.27–2.21; p<0.001). Any increase of 1 mean value in BMI would increase the adjacent segment disease rate by 67.6%. The patients were subdivided into two groups based on BMI, and up to 11.9% of patients with BMI >=25 kg/m2 were diagnosed as having adjacent segment disease at the last follow-up.”

The authors conclude that BMI is a risk factor for adjacent segment disease in patients undergoing lumbar fusion for degenerative spine diseases. In terms of practical applications of these findings, Ou et al suggest that because BMI is clinically objective and modifiable, “controlling body weight before or after surgery may provide opportunities to reduce the rate of adjacent segment disease and to improve the outcome of fusion surgery.”