On-Demand Sildenafil as a Treatment for Raynaud Phenomenon
Bibliographic record
Abstract
Background: Treatment of Raynaud phenomenon (RP) with phosphodiesterase-5 inhibitors has shown moderate efficacy. Adverse effects decrease the risk-benefit profile of these drugs, and patients may not be willing to receive long-term treatment. On-demand single doses before or during exposure to cold may be a good alternative. Objective: To assess the efficacy and safety of on-demand sildenafil in RP. Design: Series of randomized, double-blind, n-of-1 trials. (ClinicalTrials.gov: NCT02050360). Setting: Outpatients at a French university hospital. Participants: Patients with primary or secondary RP. Intervention: Each trial consisted of a multiple crossover study in a single patient. Repeated blocks of 3 periods of on-demand treatment were evaluated: 1 week of placebo, 1 week of sildenafil at 40 mg per dose, and 1 week of sildenafil at 80 mg per dose, with a maximum of 2 doses daily. Measurements: Raynaud Condition Score (RCS) and frequency and daily duration of attacks. Skin blood flow in response to cooling also was assessed with laser speckle contrast imaging. Mixed-effects models were used and parameters were estimated in a Bayesian framework to determine individual and aggregated efficacy. Results: 38 patients completed 2 to 5 treatment blocks. On the basis of aggregated data, the probability that sildenafil at 40 mg or 80 mg was more effective than placebo was greater than 90% for all outcomes (except for RCS with sildenafil, 80 mg). However, the aggregated effect size was not clinically relevant. Yet, substantial heterogeneity in sildenafil's efficacy was observed among participants, with clinically relevant efficacy in some patients. Limitation: The response to sildenafil was substantially heterogeneous among patients. Conclusion: Despite a high probability that sildenafil is superior to placebo, substantial heterogeneity was observed in patient response and aggregated results did not show that on-demand sildenafil has clinically relevant efficacy. In this context, the use of n-of-1 trials may be an original and relevant approach in RP. Primary Funding Source: GIRCI (Groupement Interrégional de Recherche Clinique et d'Innovation) Auvergne Rhône-Alpes (academic funding) and Pfizer.
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".