The Placebo Effect in Asthma Drug Therapy Trials: A Meta-Analysis
Bibliographic record
Abstract
A meta-analysis of randomized controlled asthma drug therapy trials published in the English literature from January 1991 to June 1995 was performed to estimate the magnitude and direction of the placebo effect in stable ambulatory asthmatic patients. Among placebo groups, the mean absolute increase in forced expiratory volume in 1 sec (FEV1), weighted for sample size and variance, was 0.11 L/min, and the mean percent increase in FEV1 was 4.81%. The corresponding placebo group changes in peak expiratory flow (PEF) were in an opposite direction to those of FEV1; there was a mean absolute decrease of 2.24 L/min, and a mean percent decrease of 4.21%. Changes for active treatment groups were greater in magnitude. However, there were no statistically significant differences in mean changes comparing the placebo groups to the treatment groups, for any of the outcome measures. Mean increases in PEF and FEV1 exceeded 10% in 5 of 33 placebo groups, as compared to 13 of 33 active treatment groups. In conclusion, in well-designed long-term drug therapy studies in stable asthmatics the pooled placebo effect is small but measurable, with FEV1 and PEF showing different directions of response. Moreover, a modest number of patients receiving placebo have changes in pulmonary function that might be interpreted as clinically significant.
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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 | 0.025 | 0.055 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.017 | 0.026 |
| Bibliometrics | 0.005 | 0.005 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 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".