Cost-effectiveness and cost-utility analysis of transforaminal lumbar interbody fusion versus posterolateral fusion for single-level lumbar spinal stenosis in Thailand: a bidirectional cohort study

Study Design: Bidirectional cohort and model-based economic evaluation.Purpose: This study aimed to compare the cost-effectiveness and cost-utility of open posterolateral fusion combined with transforaminal lumbar interbody fusion (PLF/TLIF) versus open posterolateral fusion (PLF) alone for single-level lumbar spinal stenosis (SLS) in Thailand from a societal perspective.Overview of Literature: Lumbar spinal stenosis is a disabling condition associated with a substantial clinical and economic burden.Although PLF/TLIF and PLF are widely used surgical options, their relative economic value remains uncertain, particularly in developing countries.Methods: A bidirectional cohort of patients with SLS treated between 2014 and 2022 was analyzed.Clinical outcomes included the EuroQol 5-dimension 5-level (EQ-5D-5L) index, the Oswestry Disability Index (ODI), and healthcare costs incurred during the 12 months following surgery.These data populated a Markov model estimating lifetime costs, quality-adjusted life years (QALYs), incremental costeffectiveness ratios, and net monetary benefit (NMB).Analyses applied a Thai willingness-to-pay threshold of US$5,003 per qualityadjusted life-year (QALY) (3% discount rate; 2022 exchange rate, US$1=31.98 Thai baht).Results: A total of 140 patients with SLS were included: 70 treated with PLF/TLIF, and 70 with PLF alone.At 12 months, the PLF/TLIF group demonstrated significantly lower disability than the PLF group (mean ODI, 22.24 vs. 37.65; p=0.02), whereas health utility was comparable between groups (EQ-5D-5L, 0.83 vs. 0.84; p=0.47).Lifetime modeling showed that PLF/TLIF generated lower total costs than PLF (US$29,248 vs. US$35,853) and slightly higher QALYs (12.04 vs. 11.70),resulting in an NMB of US$8,303 at the Thai willingnessto-pay threshold.The incremental cost was US$199 per 1-point improvement in ODI, indicating that PLF/TLIF was associated with both improved disability outcomes and lower lifetime costs compared with PLF.Conclusions: From a societal perspective in Thailand, transforaminal lumbar interbody fusion was both cost-saving and cost-effective compared to posterolateral fusion alone for SLS, yielding greater improvement in disability at a lower lifetime cost.