Cost-effectiveness of posterior lumbar interbody fusion in the Japanese universal health insurance system.

BACKGROUND

Globally, the cost-effectiveness of spinal surgery is becoming increasingly important. However, these data are limited to a few countries. The purpose of our study was to examine the cost/quality adjusted life year (cost/QALY) gained for posterior lumbar interbody fusion (PLIF) in the Japanese universal health insurance system.

METHODS

Fifty five patients underwent PLIF for lumbar degenerative spinal canal stenosis between July 2013 and September 2015 was included. Effectiveness was measured using Euro QOL 5-dimension (EQ-5D), Short-Form 8 physical component summary (PCS), and visual analog scale (VAS). The cost was calculated from the perspective of the public healthcare payer. Effectiveness and cost were measured one year after surgery. QALYs were calculated by multiplying the utility value (EQ-5D) and life years. Only direct costs were included on the basis of actual reimbursements. Cost/QALY at a 5-year time horizon with a 2% discount rate was estimated. Sensitivity analysis was performed by varying the time horizon (2 years or 10 years). The exchange rate was defined as US $1 to Japanese 100 yen.

RESULTS

Mean total cost one year after surgery was ￥2,802,900 ($28029). Operative cost was ￥1,779,700 ($17797). Mean gained score was 0.22 in EQ-5D, 10.3 in PCS, and -44 in VAS. Cost/QALY was ￥2,697,500 ($26975). Sensitivity analysis demonstrated that cost/QALY at a 10-year time horizon was ￥1,428,300 ($14283) and that cost/QALY at a 2-year time horizon was ￥6,435,400 ($64354).

CONCLUSIONS

Clinical outcomes after PLIF improved beyond minimum clinical improvement difference. Cost/QALY was below the widely-accepted benchmark (cost/QALY < $50000). PLIF could be regarded as cost-effective interventions.