Summary of inclusion and exclusion criteria.
| Variable(s) | Inclusion Criteria | Exclusion Criteria |
| Patient Factors | Adult patients with back and/or leg pain who underwent surgery for the following degenerative conditions:
| Aged <18 y Tumor Infection Cervical or thoracic spinal surgery Fracture/trauma Revision surgery Scoliosis Spinal injections |
| MASa | Single-level or multilevel posterior MAS including
| Cervical or thoracic surgery Anterior or lateral lumbar surgery Computer-assisted or robotic surgery Kyphoplasty or vertebroplasty |
| Conventional (open) surgery | Open posterior spinal procedures including
| Comparisons of 2 MAS procedures Cervical or thoracic surgery Anterior or lateral lumbar surgery |
| Outcomes | Costs analysis only Incremental cost-effectiveness ratio (or similar cost-effectiveness metric) Both open and MAS approach both analyzed for cost and/or outcomes | Differences in clinical outcomes only without cost analysis Utilities only Procedural costs not included |
| Study type | Full economic studies (cost-utility, cost-effectiveness, cost-benefit, cost-minimization) Cost studies (retrospective cohorts, nonrandomized prospective cohorts, decision model analyses) | Studies with <10 patients per treatment arm Systematic reviews |
| Publication type | Studies published in English Peer-reviewed journals | Single-center reports of multicenter studies Meeting abstracts, editorials, opinion pieces Biomechanical studies, radiographic studies, animal studies, case reports, methodologies |
Abbreviations: MAS, minimal access surgery; PLIF, posterior lumbar interbody fusion; TLIF, transforaminal lumbar interbody fusion.
↵a MAS was conducted through a tube using cylindrical soft tissue retractors in 16 studies. In one case, MAS was conducted endoscopically and compared with a conventional open approach.