A cost-consequence analysis comparing spinal fusion and decompression with decompression alone in the treatment of degenerative spondylolisthesis.

AIMS: The aim of this study was to compare outcomes of combined fusion and decompression with decompression alone in patients with lumbar degenerative sponylolisthesis. Traditional cost-effectiveness analysis was avoided due to the prospective nature of the two groups of patients.

METHODS

A cost-consequence analysis using prospective, multicentred, observational cohort data from the Canadian Spine Outcomes and Research Network database was performed from a limited societal perspective. The patients' out-of-pocket expenses were estimated from diaries. Institutional costs were estimated from case costing data from the site with greatest enrolment. Cost-effectiveness was not assessed. Instead, the outcomes and costs associated with each form of treatment are presented independently. The Oswestry Disability Index (ODI), quality-adjusted life years (QALYs) from EuroQol five-dimension questionnaire (EQ-5D-5L), and the 12-Item Short-Form Health Survey questionnaire (SF-12) were recorded as the health outcomes. The potential effects of confounding variables on outcomes were controlled using augmented inverse probability of treatment weighting.

RESULTS

There were a total of 332 patients: 248 (75%) had a fusion and decompression and 84 (25%) underwent decompression alone, between August 2015 and February 2020. There were no statistically significant differences in ODI, SF-12, and QALY scores in either the unadjusted or the adjusted models at two years between the two groups, although the baseline patient-reported outcome measures (PROMs) were significantly worse for those who underwent fusion and decompression. Fusion and decompression (CAD$13,534) was more costly compared with decompression alone ($6,540) at year one. The overall revision rate was increased in those who underwent fusion and decompression (9%) compared with decompression alone (4%).

CONCLUSION

Fusion and decompression was more costly than decompression alone. The PROMs were similar postoperatively in the two groups despite differences at baseline. Thus, fusion and decompression for most patients with lumbar degenerative sponylolisthesis would seem not to be justified financially, and future work is required to determine the baseline characteristics of the patients which would justify the increased costs.