Postoperative Length of Stay After Minimally Invasive Transforaminal Lumbar Interbody Fusion: Analysis of Perioperative Predictors.

Length of stay is a key quality and cost metric after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Published benchmarks vary widely between healthcare systems, and in tertiary referral settings total hospital stay is confounded by preoperative workup time. Whether patient-level perioperative factors independently predict extended postoperative length of stay in this procedure remains unclear. This retrospective cohort analysis included 101 consecutive patients who underwent MIS-TLIF at a single tertiary spine center between January 2019 and October 2024. To isolate surgical recovery from preoperative workup time, the primary outcome was postoperative length of stay, measured from the day of surgery to the day of discharge. Extended postoperative length of stay was pre-specified as ≥ 7 days (cohort 75th percentile). Candidate predictors-age, body mass index (BMI), preoperative C-reactive protein, number of fused levels, operative time, estimated blood loss, preoperative pain scores, Oswestry Disability Index (ODI), and perioperative complications-were screened by univariate logistic regression and entered into a multivariable model, validated by 1000-iteration bootstrap resampling. Pre-specified sensitivity analyses used cutoffs of ≥ 6 days and ≥ 5 days. Median postoperative length of stay was 4 days (interquartile range 3-6), consistent with international benchmarks. Eighteen patients (17.8%) met the primary extended-stay definition. BMI showed a marginal inverse association at the primary threshold (adjusted odds ratio (OR) 0.83, p = 0.039), but this signal did not persist at either ≥ 6-day (p = 0.12) or ≥ 5-day (p = 0.11) cutoffs, indicating that it is not robust. No patient-level perioperative factor was robustly and independently associated with extended postoperative stay. Once surgical recovery was isolated from preoperative workup time, the drivers of extended postoperative stay appeared to lie outside traditionally targeted patient-level variables, supporting a shift in focus toward system-level factors such as standardized discharge pathways and enhanced recovery protocols.