Spine Journal - 2026-08-31 - Journal Article
Two-year cost-effectiveness analysis of alternate-level instrumentation in open-door cervical laminoplasty: secondary analysis of a randomized controlled trial.
Tsujino M, Tamai K, Terakawa M, Takahashi S, Kobayashi Y, Umano M, Hoshino M, Suzuki A, Tsujio T, Yasuda H, Iwamae M, Toyoda H, Oka M, Nakamura H, Terai H
Topics
Key Takeaway
Skip-level fixation in open-door cervical laminoplasty reduced two-year direct medical costs by USD 1,460 versus all-level fixation with no significant QALY difference, yielding an 86.3% probability of cost-effectiveness at a WTP threshold of USD 45,900/QALY.
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Summary
This secondary cost-effectiveness analysis of a multicenter RCT compared skip-level versus all-level instrumentation in C3-C6 open-door laminoplasty for degenerative cervical myelopathy in patients ≥60 years, using two-year direct medical costs and EQ-5D-5L-derived QALYs within the Japanese public health insurance system. Skip-fixation produced a non-significant QALY difference (ΔQALY=0.035; 95% CI -0.083 to 0.152) while costing USD 1,460 less over two years (95% CI -2,834 to -173). The mean incremental net monetary benefit was USD 3,061 in favor of skip-fixation, with an 86.3% probability of cost-effectiveness at the prespecified WTP threshold.
Key Limitation
The two-year time horizon may not capture late complications, adjacent segment effects, or reoperations that could erode the cost advantage of skip-fixation over a clinically meaningful longer term.
Original Abstract
BACKGROUND CONTEXT
The optimal number of fixation levels in cervical open-door laminoplasty remains controversial. A recent randomized controlled trial (RCT) demonstrated that alternate-level instrumentation (skip-fixation) achieved non-inferior improvement in the Japanese Orthopaedic Association (JOA) score compared with instrumentation at every level (all-fixation). Skip-fixation requires instrumentation at approximately half of the laminar levels and may therefore theoretically reduce implant-related costs. However, the economic impact of fixation strategy has not been formally evaluated.
PURPOSE
To evaluate the cost-effectiveness of skip-fixation compared with all-fixation using two-year direct medical costs and health-related quality-of-life (HRQoL) data within the Japanese public health insurance system.
STUDY DESIGN/SETTING
A secondary cost-effectiveness analysis conducted alongside a prospective, multicenter randomized controlled trial at four hospitals in Japan.
PATIENT SAMPLE
Patients aged ≥60 years who underwent C3-C6 open-door cervical laminoplasty for degenerative cervical myelopathy in a multicenter randomized controlled trial.
OUTCOME MEASURES
Two-year cumulative direct medical costs, including surgery-related inpatient costs, postoperative outpatient costs, and costs associated with complications or reoperations, were evaluated from the payer's perspective. HRQoL was measured using the EQ-5D-5L at baseline and at 3, 12, and 24 months postoperatively, and quality-adjusted life-years (QALYs) were calculated.
METHODS
Incremental net monetary benefit (INMB) was calculated at a willingness-to-pay (WTP) threshold of JPY 5,000,000 (USD 45,900) per QALY. Uncertainty was assessed using 10,000 bootstrap replications to generate cost-effectiveness planes and acceptability curves.
RESULTS
A total of 129 patients with complete two-year cost and utility data were analyzed (66 skip-fixation; 63 all-fixation). No statistically significant difference in two-year QALYs was observed between groups (ΔQALY = 0.035; 95% CI, -0.083 to 0.152). Mean two-year total direct medical costs were lower in the skip-fixation group (ΔCost = USD -1,460; 95% CI, -2,834 to -173). At the WTP threshold of USD 45,900, the mean INMB was USD 3,061 (95% CI, -2,481 to 8,569). The probability that skip-fixation was cost-effective was 86.3%. Scenario analyses demonstrated greater economic advantage when higher-cost plate fixation was assumed.
CONCLUSIONS
Skip-fixation was cost-effective compared with all-fixation in cervical open-door laminoplasty over a two-year period. This economic advantage was more pronounced when high-cost implants were used.