Regression augmented weighting adjustment for indirect comparisons in health decision modelling
Bibliographic record
Abstract
BACKGROUND: Understanding the relative costs and effectiveness of all competing interventions is crucial to informing health resource allocations. However, to receive regulatory approval for efficacy, novel pharmaceuticals are typically only compared against placebo or standard of care. The relative efficacy against the best alternative intervention relies on indirect comparisons of different interventions. When treatment effect modifiers are distributed differently across trials, population adjustment is necessary to ensure a fair comparison. Matching-Adjusted Indirect Comparisons (MAIC) is the most widely adopted weighting-based method for this purpose. Nevertheless, MAIC can exhibit instability under poor population overlap. Regression-based approaches to overcome this issue are heavily dependent on parametric assumptions. METHODS: We introduce a novel method, 'G-MAIC,' which combines outcome regression and weighting-adjustment to address these limitations. Inspired by Bayesian survey inference, G-MAIC employs Bayesian bootstrap to propagate the uncertainty of population-adjusted estimates. We evaluate the performance of G-MAIC against standard non-adjusted methods, MAIC and Parametric G-computation, in a simulation study encompassing 18 scenarios with varying trial sample sizes, population overlaps, and covariate structures. RESULTS: Under poor overlap and small sample sizes, MAIC can produce non-sensible variance estimations or increased bias compared to non-adjusted methods, depending on covariate structures in the two trials compared. G-MAIC mitigates this issue, achieving comparable performance to parametric G-computation with reduced reliance on parametric assumptions. CONCLUSION: G-MAIC presents a robust alternative to the widely adopted MAIC for population-adjusted indirect comparisons. The underlying framework is flexible such that it can accommodate advanced nonparametric outcome models and alternative weighting schemes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.055 | 0.194 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.004 | 0.004 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.004 | 0.004 |
| Research integrity | 0.003 | 0.005 |
| Insufficient payload (model declined to judge) | 0.008 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".