Graduated compression stockings on long-haul flights,
does it really help with Reduction in asymptomatic deep-vein thrombosis detected by post-flight ultrasound?
research showsThe grade is C with 54 points. The 2021 Cochrane review included 12 randomized trials and 2,918 participants. In nine bilateral-stocking comparisons with follow-up for 2,637 people, asymptomatic DVT occurred in 3 stocking users versus 47 controls, OR 0.10 (95% CI 0.04 to 0.25). This was ultrasound-detected, symptomless thrombosis. Symptomatic DVT, pulmonary embolism, and death were each zero in both groups, but assessment and reporting of all three outcomes were not demonstrably complete across every trial, so prevention of those clinical events remains unknown.
ads claimA claim of a 90% reduction must say that the outcome was asymptomatic DVT found by post-flight ultrasound. It is not a 90% reduction in symptomatic DVT, pulmonary embolism, or death.
Useful facts when choosing a product
- Most trials used below-knee graduated stockings providing about 10 to 20 or 20 to 30 mmHg at the ankle.
- Eligibility started at four-hour flights, but all included flights exceeded five hours.
- The Scurr trial reported support from Stamford Hospital and Medi UK Ltd, so the evidence cannot be described as uniformly manufacturer-free.
What the research actually shows
Clarke and colleagues included randomized trials of flights lasting at least four hours; every included flight actually exceeded five hours. Twelve trials enrolled 2,918 participants: ten trials with 2,833 compared bilateral stockings with no stockings, one trial with 50 studied compression tights, and one with 35 used a within-person leg comparison. Nine bilateral trials contributed 2,637 participants with follow-up and found 3 versus 47 asymptomatic DVTs. Stockings generally provided 10 to 20 mmHg or 20 to 30 mmHg at the ankle. The Scurr trial explicitly listed Stamford Hospital and Medi UK Ltd as funders and used blinded outcome assessment. Manufacturer funding could not be confirmed uniformly for every included trial. Verdict 1357 is D with 34 points for leg fatigue, verdict 1829 is D with 34 points for post-thrombotic syndrome, and verdict 1889 is D with 30 points for DVT after acute stroke; their indications and endpoints differ from post-flight asymptomatic ultrasound-detected DVT.
Why this is classified as C (54)
Randomized evidence consistently supports a large reduction in ultrasound-detected asymptomatic DVT, but no symptomatic DVT, pulmonary embolism, or death occurred. Limiting the conclusion to the surrogate endpoint gives C with 54 points.
Counterpoint. Leg edema also decreased, but measurement methods varied and it was not used as the primary judged outcome.
Rejudgment record. Cross-check applied — Large reduction in asymptomatic ultrasound-detected DVT but no symptomatic DVT, pulmonary embolism, or death, requiring the surrogate-endpoint cap
| Endpoint | S | Surrogate marker - laboratory or imaging measures |
| Replication | R1 | Single confirmatory trial |
| Independence | I1 | Mixed funding sources |
| Effect size | E+ | Meets the clinically important threshold |
The scoring table and the verdict agree (C).
Sub-claim grades by effect
This ingredient is marketed for several effects. A single overall grade blends strong and weak claims together, so each effect is graded separately here. The overall grade reflects the strongest disconfirming or core claim.
| Effect (sub-claim) | Grade | Basis |
|---|---|---|
| Reduction in ultrasound-detected asymptomatic DVT | C | There were 3 versus 47 events, OR 0.10. |
| Reduction in symptomatic DVT | ? | Both groups had zero events, preventing effect estimation. |
| Reduction in pulmonary embolism or death | ? | No pulmonary embolism or death was reported. |
Cross-check — Codex and Claude
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Study 1 | Systematic review of randomized trials | 2,637 | Varied by trial; the Scurr trial reported support from Stamford Hospital and Medi UK Ltd | Asymptomatic DVT detected by ultrasound from immediately after flight to 48 hours | 3 versus 47 events; OR 0.10 (95% CI 0.04 to 0.25). Symptomatic DVT, pulmonary embolism, and death were all zero. | Primary evidence for the verdict |
Receipt — 2 References
All 2 cited sources were verified for existence at the original page (as of 2026-08-06).
Reviewed and approved: Chamgap Editorial Team · Approval date: 2026-08-06 · Corrections: none
Cite this verdict
[Chamgap] Graduated compression stockings on long-haul flights x asymptomatic DVT — Evidence Grade C·54. 2 cited sources checked. Source: https://chamgap.com/en/verdicts/heart/graduated-compression-stockings-long-haul-flight-asymptomatic-dvt/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
What this document does and does not do
Chamgap is an information source. It reports what research has and has not confirmed; it does not tell readers what to take or buy. That decision belongs to readers and, when needed, medical or legal professionals. This verdict reflects literature available up to the search date and may change as new research appears. Nothing here is medical advice.