Clinically informative measures of the effect of drugs or other interventions
Bibliographic record
Abstract
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Several comparative measures (ratios, differences, or the number needed to treat) are used to express the effect of a drug or another intervention. These measures can vary in the way they are affected by the background risk measured from the reference group. WHAT THIS STUDY ADDS: This paper reviews the formulation, interpretation and limitations of measures of effect. We describe a little-known parameter, the attained effect or clinical result ratio, a positive reformulation of the relative risk difference, and suggest how available parameters can be best used to summarize results of studies of the effect of drugs. AIMS Measures to compare two drugs are often affected by the background risk in the reference group; a ceiling effect results when the background risk is small. We review measures of the effect of drugs, including a special formulation of the relative risk difference, the attained effect or clinical result ratio, that addresses background risk and ceiling effect. METHODS: Existing measures are the risk and odds ratios, the absolute and relative risk differences, and the number needed to treat. The attained effect is defined as the observed gain in success (the difference of proportion of success between the two interventions), divided by the maximum attainable gain, the maximum proportion of success one can expect. We illustrate the relationship between these measures with published results of two meta-analyses. RESULTS: In studies of the effectiveness of cell salvage, the baseline risk ranged between 8 and 95%. This variability affected the risk difference and number needed to treat, while the attained effect, with a ceiling residual risk of 2%, showed that the gain in success was half the maximum attainable gain. In studies of the effectiveness of therapy in patients infected by the human immunodeficiency virus, where the baseline risk was less variable, and there was no ceiling effect, the maximum attained effect indicated that the gain could be much smaller. CONCLUSION: The attained effect, interpreted as the proportion of effectiveness that remains to gain for future interventions, can usefully complete the number needed to treat as a clinically informative effect measure.
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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 | 0.139 | 0.361 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.009 | 0.013 |
| Bibliometrics | 0.008 | 0.007 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.007 | 0.008 |
| Open science | 0.004 | 0.003 |
| Research integrity | 0.005 | 0.007 |
| Insufficient payload (model declined to judge) | 0.015 | 0.002 |
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".