Trial reportBMJ open2026
Within-person variability and the minimal important difference of the EQ-VAS in adults with post-COVID-19 condition: a secondary analysis of data from a single-centre randomised controlled trial.
Trial report in BMJ open, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT05890534 (Pycnogenol® in People With Post-COVID-19 Condition), which is not on this map. Not yet cited in PubMed.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Pycnogenol® in People With Post-COVID-19 Condition: a Quadruple-blind, Randomized, Placebo-controlled Trial
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Authors and funding
9 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectiveTo describe the distribution and day-to-day variability of EuroQol Visual Analogue Scale (EQ-VAS) values and to estimate a minimal important difference (MID) in adults with post-COVID-19 condition (PCC).
designSecondary analysis of pooled EQ-VAS data from both arms of a 12-week randomised, placebo-controlled trial (PYCNOVID) of Pycnogenol (200 mg/day) versus placebo in adults with PCC.
settingSingle centre study in Switzerland between June 2023 and July 2024.
participantsAdults with PCC with at least one of the following symptoms: fatigue, post-exertional malaise, dyspnoea or brain fog.
main outcome measureEQ-VAS ratings over 7 consecutive days before baseline (randomisation) and at follow-up (after 12 weeks). Weekly mean EQ-VAS values and within-person SDs (wpSD) were calculated. The MID was estimated using distribution-based and anchor-based methods with prespecified correlation criteria, using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) instrument as the primary anchor, along with additional anchors.
resultsAmong 153 participants, baseline EQ-VAS values were low, with a median of 48.7 on a 0-100 scale. Day-to-day variability was considerable, with a median wpSD of 6.4. Distribution-based MID estimates ranged from 5.9 to 8.9 points. FACIT-Fatigue was the only anchor meeting the correlation threshold (ρ≥0.30), yielding an anchor-based MID of 8.96 points. Triangulation of these estimates supported a final MID estimate of 8 EQ-VAS points.
conclusionsAdults with PCC reported markedly impaired and highly variable health status. Weekly aggregation of daily EQ-VAS ratings likely provides a more robust estimate than single-day assessments. A PCC-specific EQ-VAS MID of 8 points, derived from a chronic, fatigue-predominant PCC population, facilitates interpretation of meaningful change and improves outcome definition and sample size planning in future studies. Applicability to earlier-stage or non-fatigue-predominant PCC populations warrants further investigation. TRIAL REGISTRATION NUMBER: NCT05890534.
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