TABLE 2.
Prespecified exploratory subgroup meta-analyses of AUROC.
| Subgroup domain | n | Pooled AUROC (95% CI) | 95% prediction interval | I2 | P |
|---|---|---|---|---|---|
| Validation level | 0.572 | ||||
| Development only/unclear | 8 | 0.811 (0.740–0.867) | 0.551–0.938 | 99 | |
| External validation | 9 | 0.749 (0.697–0.795) | 0.580–0.865 | 96 | |
| Internal split/holdout validation | 9 | 0.800 (0.696–0.875) | 0.404–0.959 | 99 | |
| Resampling/internal validation | 9 | 0.834 (0.658–0.929) | 0.214–0.989 | 96 | |
| Validation status | 0.170 | ||||
| Development/internal validation | 26 | 0.811 (0.755–0.856) | 0.480–0.952 | 99 | |
| External/temporal validation | 9 | 0.749 (0.697–0.795) | 0.580–0.865 | 96 | |
| Baseline opioid status | 0.021 | ||||
| Mixed/prior use included | 28 | 0.812 (0.764–0.853) | 0.521–0.945 | 99 | |
| Opioid-naive | 7 | 0.713 (0.638–0.778) | 0.498–0.862 | 89 | |
| Prediction timing | 0.325 | ||||
| Intraop/discharge/in-hospital | 11 | 0.843 (0.723–0.916) | 0.349–0.982 | 99 | |
| Postoperative-updated | 5 | 0.771 (0.677–0.843) | 0.482–0.924 | 97 | |
| Preoperative only | 19 | 0.777 (0.723–0.824) | 0.499–0.925 | 98 | |
| Surgical/procedure domain | 0.981 | ||||
| Mixed surgery | 8 | 0.796 (0.728–0.851) | 0.550–0.926 | 99 | |
| Orthopaedic/extremity | 14 | 0.794 (0.683–0.873) | 0.346–0.966 | 95 | |
| Spine/neurosurgery | 7 | 0.800 (0.739–0.850) | 0.601–0.914 | 89 | |
| Other/non-orthopaedic | 6 | 0.806 (0.612–0.917) | 0.249–0.981 | 99 | |
| Model class | 0.246 | ||||
| Conventional regression | 7 | 0.732 (0.659–0.794) | 0.506–0.879 | 96 | |
| Machine learning/penalized model | 18 | 0.825 (0.742–0.885) | 0.394–0.971 | 100 | |
| Other/unclear | 2 | 0.851 (0.435–0.977) | Not estimable | 96 | |
| Risk score/calculator/existing model | 8 | 0.771 (0.738–0.801) | 0.673–0.846 | 84 | |
| Outcome-window | 0.098 | ||||
| Early extended window: >30 days to <90 days | 3 | 0.766 (0.733–0.797) | 0.660–0.847 | 0 | |
| Intermediate window: around 90–180 days | 6 | 0.714 (0.657–0.765) | 0.547–0.837 | 95 | |
| Long window: ≥6 or 6–12 months | 22 | 0.829 (0.768–0.877) | 0.481–0.962 | 99 | |
| Unclear/mixed follow-up window | 4 | 0.733 (0.673–0.786) | 0.558–0.857 | 82 | |
| Operational outcome | 0.683 | ||||
| Any fill/refill/use at follow-up definition | 17 | 0.801 (0.712–0.868) | 0.373–0.965 | 98 | |
| Other or unclear operational definition | 3 | 0.740 (0.414–0.920) | 0.001–1.000 | 96 | |
| Repeated or sustained prescription/supply definition | 15 | 0.798 (0.756–0.835) | 0.635–0.900 | 98 | |
| Calibration reporting | 0.014 | ||||
| Calibration not reported | 13 | 0.856 (0.757–0.919) | 0.377–0.983 | 99 | |
| Calibration reported | 22 | 0.759 (0.727–0.789) | 0.589–0.874 | 98 | |
| DCA reporting | 0.125 | ||||
| DCA not reported | 24 | 0.815 (0.755–0.863) | 0.466–0.957 | 99 | |
| DCA reported | 11 | 0.751 (0.707–0.790) | 0.581–0.867 | 98 | |
| PROBAST overall | 0.438 | ||||
| High | 9 | 0.834 (0.658–0.929) | 0.212–0.989 | 98 | |
| Low | 6 | 0.735 (0.691–0.775) | 0.610–0.831 | 87 | |
| Unclear | 20 | 0.800 (0.751–0.840) | 0.538–0.932 | 100 | |
Abbreviations: AUROC, area under the receiver operating characteristic curve; CI, confidence interval; DCA, decision curve analysis; PROBAST, Prediction model Risk Of Bias Assessment Tool. I2 denotes the proportion of total variability attributable to between-study heterogeneity, and n denotes the number of independent study-level estimates. P values are omnibus tests of between-subgroup differences.
Subgroup classifications were independently assigned at the study level according to the definitions reported in the original articles and were intended for exploratory interpretation. Validation level describes the four-category validation design: development only/unclear, internal split/holdout validation, resampling/internal validation and external validation. Validation status collapses these categories into development/internal validation versus external/temporal validation for the principal comparison.
Surgical/procedure domains were classified as orthopaedic/extremity surgery, including ACL, reconstruction, meniscal or other knee/hip arthroscopy, arthroplasty, hand or upper-extremity surgery, shoulder/rotator cuff surgery and pelvic or hip fracture surgery; spine/neurosurgery, including ACDF, lumbar disc or spine surgery and major spine surgery; mixed surgery, including heterogeneous surgical or mixed adolescent cohorts; or other/non-orthopaedic procedures, including cesarean delivery, other surgical cohorts and major elective surgery under general anesthesia.
Model class was assigned according to the primary model reported in Table 3: conventional regression, including multivariable logistic regression; machine-learning/penalised model, including gradient boosting, naive Bayes, bagging and other algorithmic or penalised approaches; risk score/calculator/existing model, including the SOS score and other previously developed or externally validated tools, such as SORG-MLA; or other/unclear model, including hybrid approaches or models with insufficient methodological detail. When multiple models were reported, classification followed the primary model selected for the meta-analysis.
Outcome-window categories were based on the reported follow-up period for prolonged postoperative opioid use, and operational-definition categories were based on whether opioid use was defined by any fill, refill or use; repeated or sustained prescription or supply; or another/unclear criterion.