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Open WellbeingWhat the studies actually measured

Heart and blood pressure

Ironand Six-Minute Walk Test Distance

Only one source here so far, and it measured higher six-Minute Walk Test Distance.

How sure anyone can be

Low certainty, level 2 of 4

Further research is likely to change this.

The numbers reported

One source’s range, drawn against its own line of no difference and scaled to its own numbers.

11.9529.1946.43

This range stays on one side of the no-difference line.

Bar the confidence interval — the range the true effect is likely to sit inNotch the number the source reportedLine where there would be no difference at all

One source, newest first

What we read is the published abstract, not the full paper, so a blank below may still be printed in the paper itself. A fixed rule worked this out from the source’s own fields. Nobody checked this rating by hand.

  • Systematic review, 2026

    Low certainty, level 2 of 4

    Intravenous ferric carboxymaltose in patients with heart failure and iron deficiency: a systematic review and meta-analysis of randomized controlled trials with trial sequential analysis.

    ESC Heart Fail. 2026;13(1). doi:10.1093/eschf/xvaf018. PMID:41711738.

    Number reported
    29.19
    Which way it went
    Higher
    Likely range
    11.95 to 46.43
    Source’s own words
    metres mean difference in 6-minute walk test vs control
    Who was studied
    Patients with heart failure and iron deficiency
    Compared with
    placebo
    Amount taken
    Not in the abstract
    For how long
    Not in the abstract
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 2 steps down: risk of bias and imprecision
    1. Starts at High
    2. Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
    3. Imprecision brought it down to Lowthe abstract does not state how many participants were pooledNot in the abstract
    4. Ends at Low2 steps down.
    Checked, nothing to step it down for
    indirectness
    Inconsistency
    No disagreement reported, and no count of studies behind it

    Imprecision stops at the first check that applies; others may apply too.

    Source saved; quote checked byte-for-byte against it by software; no signature.

    Read the abstract on PubMed

What is still missing from these readings

  • One do not say how many people took part.
  • Amount taken — Not in the abstract.
  • For how long — Not in the abstract.

Something nobody wrote down is never a zero and never a guess.

Still to read for Iron

Eight of the 18 things on our list for Iron have no reading here yet:

  • Bloating Symptom Severity Score
  • Endurance Performance (Time to Exhaustion)
  • Fractional iron absorption
  • Heart rate variability (RMSSD)
  • Hematocrit
  • Serum iron
  • Soluble Transferrin Receptor (sTfR)
  • Total Iron Binding Capacity

Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.

Read next

This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.