Learning curve and hospital resource utilization of unilateral biportal endoscopic lumbar decompression: a CUSUM analysis

Abstract

Unilateral biportal endoscopic (UBE) surgery has been increasingly adopted for lumbar degenerative diseases; however, its learning curve and impact on healthcare resource utilization remain incompletely understood. A retrospective analysis was conducted in 37 consecutive patients who underwent UBE lumbar decompression by a single surgeon. Operative time per level was evaluated using cumulative sum (CUSUM) analysis. Comparisons were performed between the earlier and later phases according to the CUSUM-derived transition point. Correlation, multivariable regression, and sensitivity analyses evaluated the relationships between operative efficiency, hospitalization parameters, and healthcare costs. CUSUM analysis demonstrated an apparent transition in operative efficiency at Case 24. Operative time per level was significantly shorter in the later phase (144.8 ± 45.3 vs. 93.9 ± 25.9 min, p < 0.001), and multivariable regression confirmed that increasing surgical experience was independently associated with shorter operative time per level after adjustment for age, body mass index, American Society of Anesthesiologists physical status, and number of operated levels. No statistically significant between-phase differences were observed in total length of stay, postoperative length of stay, total hospitalization cost, or DPC reimbursement. By contrast, adjusted multivariable analysis showed that increasing case number was independently associated with shorter total length of stay, but not postoperative length of stay. Cost structure analysis showed no significant between-phase differences in individual cost components. Sensitivity analyses using alternative CUSUM cutoffs yielded consistent results for the primary outcome. Hospitalization duration was strongly associated with total hospitalization cost (ρ = 0.914, p < 0.001) and DPC reimbursement (ρ = 0.892, p < 0.001). Operative efficiency improved progressively with increasing surgical experience in UBE lumbar decompression. However, no statistically significant between-phase differences were observed in hospitalization parameters or healthcare costs. Hospitalization duration showed the strongest association with healthcare expenditure, suggesting that perioperative management and discharge planning may influence healthcare resource utilization more than operative efficiency alone.