Prompt versus Delayed Triple Therapy in COPD: Solutions to Time-Related Biases in Observational Studies
Bibliographic record
Abstract
Samy Suissa,1– 3 Sophie Dell’Aniello,1 Michael Andrew Webster-Clark,1,2 Pierre Ernst1– 3 1Centre for Clinical Epidemiology, Lady Davis Institute-Jewish General Hospital, Montreal, QC, Canada; 2Department of Medicine, McGill University, Montreal, QC, Canada; 3Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, CanadaCorrespondence: Samy Suissa, Centre for Clinical Epidemiology, Lady Davis Institute-Jewish General Hospital, 3755 Cote Ste-Catherine, H-461, Montreal, QC, H3T 1E2, Canada, Tel +1 514 340 7593, Fax +1 514 340 7564, Email samy.suissa@mcgill.caBackground: Recent observational studies have reported that prompt initiation of single-inhaler triple therapy after a COPD exacerbation is more effective than delayed initiation. We show that their study design, by “peeking into the future” to define the timing of treatment initiation, introduces time-related biases, particularly protopathic bias. These biases can be avoided using the “cloning” approach to emulate a randomized trial approach.Methods: We formed a cohort of patients with COPD who had an exacerbation (index) after September 2017, using the United Kingdom’s Clinical Practice Research Datalink (CPRD). Using the “cloning” trial emulation technique, each subject was assigned to both the prompt and the delayed initiator arms as of the index date and censored according to their treatment over time. The Cox model was used to compare the incidence of the first exacerbation after the index exacerbation, over one year, after weighing by inverse probability of censoring. We also replicated the biased approach of the recent studies, based on peeking into the future.Results: The cohort included 91,958 eligible subjects who had an exacerbation, generating 91,958 prompt initiator clones and 91,958 delayed initiator clones. The hazard ratio (HR) of a moderate or severe exacerbation, comparing prompt versus delayed initiators, was 0.98 (95% CI: 0.80– 1.19), while it was 1.26 (95% CI: 0.81– 1.96) for severe exacerbation. The replication of the time-related biased approach comparing prompt with delayed initiation resulted, correspondingly, in HRs of 0.73 (95% CI: 0.65– 0.81) and 0.58 (95% CI: 0.46– 0.74).Conclusion: Using a trial emulation approach, prompt treatment with single-inhaler triple therapy after a COPD exacerbation was not more effective than delayed treatment at reducing the incidence of subsequent exacerbations. The method used by previous studies, suggesting significant effectiveness with prompt treatment initiation, was affected by time-related biases induced by peeking into the future. A randomized controlled trial can confirm these findings.Keywords: cohort studies, COPD exacerbations, protopathic bias, real-world evidence, treatment timing
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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 | 0.743 | 0.857 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.004 | 0.007 |
| Bibliometrics | 0.004 | 0.011 |
| Science and technology studies | 0.003 | 0.008 |
| Scholarly communication | 0.007 | 0.009 |
| Open science | 0.008 | 0.010 |
| Research integrity | 0.007 | 0.008 |
| Insufficient payload (model declined to judge) | 0.003 | 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".