Class 2/3 Obesity Leads to Significantly Worse Outcomes Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

Introduction: No previous study has analyzed the impact of class 2/3 obesity (body mass index, BMI >35) on outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). This study aimed to analyze outcomes of MIS TLIF in class 2/3 obese patients and compare them with other BMI groups.

Methods: This retrospective cohort study included patients who underwent primary single-level MIS TLIF for degenerative lumbar pathology and had a minimum of 1-year follow-up. Outcome measures were: 1) Patient reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS); 2) Global rating change (GRC), minimal clinically important difference (MCID), and patient acceptable symptom state (PASS) achievement; 3) Return to activities; and 4) Complication/reoperation rates. Patients were divided into 4 cohorts: normal (BMI 18.5 to < 25), overweight (25 to < 30), class 1 obesity (30 to < 35), and class 2/3 obesity (BMI >35). Two postoperative timepoints were defined – early ( < 6 months) and late (>6 months). Outcome measures were compared between the groups.

Results: 390 patients were included (119 normal, 160 overweight, 67 class 1 obesity, 44 class 2/3 obesity). Class 2/3 obesity patients had significantly worse ODI, VAS back, VAS leg, and SF-12 PCS at the late postoperative timepoint (>6 months). Class 2/3 obesity group had significantly lower PASS achievement rates (43% vs. >67% in other groups, p=0.01) and significantly lower MCID achievement rates in VAS leg (41% vs. >61% in other groups, p=0.04) and SF-12 PCS (41% vs. >65% in other groups, p=0.04) at >6 months. Class 2/3 obesity group had significantly higher postoperative length of stay (LOS) (62 hours vs. < 50 hours in other groups, p=0.006) and took significantly greater number of days to return to driving (74 days vs. < 40 days in other groups, p=0.015). No significant difference was found in return to work, discontinuation of narcotics, fusion rates, and complication/reoperation rates between the groups.

Conclusion : Class 2/3 obese patients had significantly worse clinical outcomes at >6 months. They took longer to be discharged from the hospital and return to driving following surgery.