Relationship between total hip replacement appropriateness and surgical priority instruments.

Rationale: Variability in indications for total hip replacement (THR) and unequal waiting times may limit health care access.

Objective: To analyse the relationship between appropriateness and previously developed surgical priority instruments.

Method: Multicentre cross-validation study of patients placed on the waiting list for THR. Information on surgical priority, surgeons' evaluation of priority through a visual analogue scale (VAS) and health-related quality of life (HRQOL) (Health Utilities Index mark 3, EQ-5D, Western Ontario McMaster Osteoarthritic Index) was collected. THR indications were considered appropriate, uncertain or inappropriate according to appropriateness criteria. Statistical differences and clinically important differences in surgical priority, VAS and HRQOL between appropriateness categories were analysed with the Mann-Whitney U-test and effect size (ES), respectively. Surgical priority score's ability to discriminate appropriate and inappropriate indications was evaluated through the area under the receiver-operating characteristic curve (AUC) and its 95% confidence interval (95% CI).

Results: 49.4% (87) of the THR indications were deemed appropriate, 39.8% (70) uncertain and 10.8% (19) inappropriate. Differences in surgical priority score, VAS and HRQOL between appropriateness categories were statistically significant. Clinically important differences were generally small (ES, 0.2-0.5) between inappropriate and uncertain, moderate (ES, 0.5-0.8) between uncertain and appropriate, and large (ES > 0.8) between inappropriate and appropriate categories. The AUC to discriminate appropriate and inappropriate indications was 0.97 (95% CI: 0.96-0.99) and 0.90 (95% CI: 0.83-0.97), respectively.

Conclusions: The relationship between the surgical priority and appropriateness instruments reinforces their validity and could improve waiting list management by establishing maximum waiting periods based on patients' characteristics.