Characterizing utilization patterns and reoperation risk factors of interspinous process devices: analysis of a national claims database

Introduction: Interspinous process devices (IPDs) were developed as minimally invasive alternatives to open decompression surgery for spinal stenosis. However, given high treatment failure and reoperation rates, there has been minimal adoption by spine surgeons. This study leveraged a national claims database to characterize national IPD usage patterns and postoperative outcomes after IPD implantation. Method: Using the PearlDiver database, we identified all patients who underwent 1- or 2-level IPD implantation between 2010 and 2018. Univariate and multivariable logistic regression was performed to identify predictors of the number of IPD levels implanted and reoperation up to 3 years after the index surgery. Right-censored Kaplan-Meier curves were plotted for duration of reoperation-free survival and compared with log-rank tests. Results: Patients (n ¼ 4865) received 1-level (n ¼ 3246) or 2-level (n ¼ 1619) IPDs. Patients who were older (adjusted odds ratio [aOR] 1.02, 95% confidence interval [CI] 1.01–1.03, P < .001), male (aOR 1.31, 95% CI 116–1.50, P < .001), and obese (aOR 1.19, 95% CI 1.05–1.36, P < .01) were significantly more likely to receive a 2-level IPD than to receive a 1-level IPD. The 3-year reoperation rate was 9.3% of patients when mortality was accounted for during the follow-up period. Older age decreased (aOR 0.97, 95% CI 0.97–0.99, P ¼ .0039) likelihood of reoperation, whereas 1-level IPD (aOR 1.37, 95% CI 1.01–1.89, P ¼ .048), Charlson Comorbidity Index (aOR 1.07, 95% CI 1.01–1.14, P ¼ .018), and performing concomitant open decompression increased the likelihood of reoperation (aOR 1.68, 95% CI 1.35–2.09, P ¼ .0014). Conclusion: Compared with 1-level IPDs, 2-level IPDs were implanted more frequently in older, male, and obese patients. The 3-year reoperation rate was 9.3%. Concomitant open decompression with IPD placement was identified as a significant risk factor for subsequent reoperation and warrants future investigation.