Risk of Pseudoarthrosis After Spinal Fusion: Analysis From the Healthcare Cost and Utilization Project

Background: Pseudoarthrosis after spinal fusion is an important cause of pain, neurologic decline, and reoperation. Methods: The Healthcare Cost and Utilization Project State Inpatient Databases were queried in New York, California, Florida, and Washington for adult patients who had undergone new spinal fusion from 2009 to 2011. In accordance with the Healthcare Cost and Utilization Project methods series and analysis guidelines, generalized linear mixed effects models were used to estimate the odds of experiencing postoperative pseudoarthrosis as a function of multivariable patient characteristics, comorbidities, and surgical approach. Results: Of the 107,420 patients who had undergone cervical fusion, 1295 (1.2%) developed pseudoarthrosis requiring reoperation. On multivariable analysis, the risk factors included posterior (odds ratio [OR], 4.47; 95% confidence interval [CI], 3.92–5.10) and combined (OR, 1.77; 95% CI, 1.33–2.36) approaches, fusion of ≥9 vertebrae (OR, 2.54; 95% CI, 1.38–4.68), smoking (OR, 1.19; 95% CI, 1.05–1.34), and long-term steroid use (OR, 1.89; 95% CI, 1.18–3.00). Of the 148,081 patients who underwent thoracic or lumbar fusion, 2665 (1.8%) developed pseudoarthrosis. Posterior (OR, 0.58; 95% CI, 0.51–0.56) and combined (OR, 0.46; 95% CI, 0.40–0.54) approaches resulted in reduced rates. Fusion of 4–8 vertebrae (OR, 1.52; 95% CI, 1.39–1.67), ≥9 vertebrae (OR, 1.87; 95% CI, 1.49–2.34), hypertension (OR, 1.18; 95% CI, 1.09–1.28), sleep apnea (OR, 1.48; 95% CI, 1.26–1.72), smoking (OR, 1.22; 95% CI, 1.12–1.33), and long-term steroid use (OR, 1.53, 95% CI, 1.08–2.18) resulted in increased rates. Conclusions: These findings strongly associate several diagnoses with the development of pseudoarthrosis. However, further prospective studies are warranted to establish causation.