Study quality assessment—QHES Score.
| Study | Study Type and Data Source | Country | Surgery Type | QHES Score | Quality of Economic Studya |
| Slotman 199812 | RC cost analysis from hospital charges database | USA | Open vs lap discectomy | 24 | Poor |
| VD Akker 201113 | CEA using Euro QOL 5D from randomized controlled trial | Holland | Open vs MIS discectomy | 79 | Good |
| Lucio 201214 | PNRC cost analysis from hospital charges database | USA | 1- and 2-level MIS-TLIF vs open TLIF | 37 | Poor |
| Parker 201215 | PNRC CEA using Euro QOL 5D | USA | Single-level MIS-TLIF vs open TLIF | 57 | Fair |
| Wang 201216 | RC cost analysis | USA | 1- and 2-level MIS vs open posterior lumbar interbody fusion | 41 | Fair |
| Pelton 201217 | PNRC cost analysis | USA | Open vs MIS single-level TLIF | 47 | Fair |
| Udeh 201218 | Cost-utility analysis using Euro QOL 5D and decision model analysis | USA | Open vs MIS laminectomy | 76 | Good |
| Cahill 201319 | RC cost analysis from hospital charges database | USA | Open vs MIS discectomy | 29 | Poor |
| Parker 201320 | RC CEA | USA | Open vs MIS laminectomy | 55 | Fair |
| Singh 201321 | PNRC cost analysis from hospital costs database | USA | Open vs MIS single-level TLIF | 37 | Poor |
| Parker 201422 | CEA using Euro QOL 5D from PNRC | USA | Single-level open vs MIS-TLIF | 75 | Good |
| Sulaiman 201423 | RC cost analysis from hospital charges database | USA | Open vs MIS-TLIF | 26 | Poor |
| Maillard 201424 | RC cost-minimization study (cost-effectiveness measured by hospital cost vs reimbursement) | France | Open vs MIS-TLIF (max 3 levels) | 62 | Fair |
| R’saud 201525 | RC CEA using Euro QOL 5D | Canada | 1- and 2-level open vs MIS-TLIF | 74 | Good |
| Vertuani 201526 | CEA using Euro QOL 5D and decision model analysis | UK/Italy | 1- and 2-level open vs MIS-TLIF | 74 | Good |
| G’hoke 201627 | RC CEA using Euro QOL 5D | USA | 1-level open vs MIS-TLIF | 68 | Fair |
| Djurasovic 201928 | PNRC using EQ-5D and SF-6D | USA | 1- and 2-level Open vs MIS-TLIF | 71 | Fair |
Abbreviations: CEA, cost-effectiveness analysis; MIS, minimally invasive surgery; PNRC, prospective nonrandomized cohort study; QHES, Quality of Health Economic studies; RC, retrospective cohort study; TLIF, transforaminal lumbar interbody fusion.
Note: Components are weighted by importance (as concluded by expert health economists) to yield a score from 0 to 100 (lowest to highest quality). Literature has suggested that a score of 75–100 points indicates a high-quality economic study. The QHES does not provide insight into study external validity (generalizability) nor does it directly assess the validity of clinical assumptions and inputs.
↵a QHES is a well-validated practical quantitative tool for appraising the quality of cost-effectiveness studies. It assesses multiple aspects of economic study design and reporting to determine internal validity.