Channeling effects in the prescription of new therapies: the case of emicizumab for hemophilia A
Bibliographic record
Abstract
Aim: To determine if emicizumab was channeled to clinically complex people with hemophilia A upon approval. Methods: Claims data (16 November 2017, through 31 December 2019) from US-based insurance databases were analyzed to compare the clinical complexity of people with hemophilia A initiating emicizumab with matched individuals receiving factor VIII (FVIII) episodically or prophylactically. People with hemophilia A with evidence of previous bypassing agent use (indicating FVIII inhibitors) were excluded. Outcomes included bleeding events, arthropathy, pain, comorbidities and healthcare costs. Results: A larger proportion of emicizumab users had bleeding events, comorbidities and arthropathy and greater healthcare costs in the year prior to starting emicizumab compared with FVIII users. Conclusion: Claims-based data limitations prevent an absolute conclusion. Nevertheless, emicizumab users appear more clinically complex than FVIII users, suggesting post-approval channeling.
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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 | 0.009 | 0.064 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
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".