The Effect of Morbid Obesity on Complications, Readmission, and Patient-Reported Outcomes Following Minimally Invasive Transforaminal Lumbar Interbody Fusion: An Inverse Propensity Score Weighted Analysis.

Study Design: Retrospective review of prospectively collected data at a single institution.

Objective: To compare perioperative and clinical outcomes in morbidly obese patients who underwent minimally invasive transforaminal lumbar interbody fusion (MiTLIF).

Summary Of Background Data: Obesity remains a serious public health concern. Obese patients who undergo lumbar fusion have historically thought to be at higher risk for complications and fare worse regarding quality-of-life outcomes. However, recent literature may demonstrate comparable risk and outcomes in obese patients. An increasing number of patients are categorized as morbidly obese (body mass index [BMI] ≥ 40 kg/m2). Perioperative and patient-reported outcomes (PROs) are lacking in this patient population.

Methods: The authors retrospectively reviewed a prospectively collected database of all morbidly obese and non-obese patients that underwent MiTLIF between 2015 and 2018 for degenerative conditions who had minimum 1-year follow-up for outcome assessment. An inverse propensity/probability of treatment weighting was utilized to create a synthetic weighted sample in which covariates were independent of obesity designation to adjust for imbalance between groups. Generalized estimating equations (GEE) was used to estimate the association of morbid obesity and complications and 1-year PROs.

Results: A total of 292 patients were analyzed with 234 non-obese patients and 58 morbidly obese patients. Multivariate analysis failed to demonstrate any association between morbid obesity and achieving minimal clinically important difference (MCID) for Oswestry disability index (ODI), visual analog scale (VAS), or short form-12 (SF-12) physical component score. However, morbid obesity was associated with significant decrease in odds of achieving MCID for SF-12 mental component score (P = 0.001). Increased surgery duration was significantly associated with morbid obesity (P = 0.001). Morbid obesity exhibited no statistically significant association with postoperative complications, readmission, pseudarthrosis, or adjacent segment disease (ASD).

Conclusion: Morbidly obese patients who undergo MiTLIF can achieve meaningful clinical improvement comparable to nonobese patients. Morbid obesity was associated with longer surgical times but was not associated with postoperative complications, readmission, or ASD.Level of Evidence: 3.