MD, PhD, MAE, FMedSci, FRSB, FRCP, FRCPEd.

It seems that no ancient treatment is daft enough for some researchers of so-called alternative medicine (SCAM) to not pick it up. Even bloodletting is back, it seems!

The aim of this study was to investigate the effects of therapeutic phlebotomy on ambulatory blood pressure in patients with grade 1 hypertension. In this randomized-controlled intervention study, patients with unmedicated hypertension grade 1 were randomized into an intervention group (phlebotomy group; 500 mL bloodletting at baseline and after 6 weeks) and a control group (waiting list) and followed up for 8 weeks. The primary endpoint was the 24-h ambulatory mean arterial pressure between the intervention and control groups after 8 weeks. Secondary outcome parameters included ambulatory/resting systolic/diastolic blood pressure, heart rate, and selected laboratory parameters (e.g., hemoglobin, hematocrit, erythrocytes, and ferritin). Resting systolic/diastolic blood pressure/heart rate and blood count were also assessed at 6 weeks before the second phlebotomy to ensure safety. A per-protocol analysis was performed.

Fifty-three hypertension participants (56.7 ± 10.5 years) were included in the analysis (n = 25 intervention group, n = 28 control group). The ambulatory measured mean arterial pressure decreased by -1.12 ± 5.16 mmHg in the intervention group and increased by 0.43 ± 3.82 mmHg in the control group (between-group difference: -1.55 ± 4.46, p = 0.22). Hemoglobin, hematocrit, erythrocytes, and ferritin showed more pronounced reductions in the intervention group in comparison with the control group, with significant between-group differences. Subgroup analysis showed trends regarding the effects on different groups classified by serum ferritin concentration, body mass index, age, and sex. Two adverse events (AEs) (anemia and dizziness) occurred in association with the phlebotomy, but no serious AEs.

The authors concluded that therapeutic phlebotomy resulted in only minimal reductions of 24-h ambulatory blood pressure measurement values in patients with unmedicated grade 1 hypertension. Further high-quality clinical studies are warranted, as this finding contradicts the results of other studies.

This paper requires a few short comments:

  1. The effect on blood pressure was not ‘minimal’, as the authors pretend, it was non-existent (i.e. not significant and due to chance only).
  2. This lack of effect had to be expected considering human physiology.
  3. The fact that hemoglobin, hematocrit, erythrocytes, and ferritin all change after bloodletting is equally expected.
  4. Mild adverse effects are also no surprise.
  5. What is a surprise, however, that such a trial was ever conducted and passed by an ethics committee. Any medic who has not slept through his/her cardiovascular physiology lectures could have predicted the results quite accurately. And running a trial where the result is well-known before the study has started can hardly be called ethical.

3 Responses to Bloodletting for hypertension? What’s next? Amputations for weight loss?

  • At the end of the abstract the authors conclude:
    “Further high-quality clinical studies are warranted, as this finding contradicts the results of other studies. ”

    I would be interested to know what these other studies were that apparently found differently.

    They also state:
    “Two adverse events (AEs) (anemia and dizziness) occurred in association with the phlebotomy, but no serious AEs.”
    I would also be interested to know what the baseline haemoglobin and iron levels were in those and other subject.

    Finally I would like to know a bit more about the trial design, particularly statistical considerations such as the size of the expected change in blood pressure and the power of the trial to find a difference if it was really there.

    Unfortunately the full text of the paper is behind a paywall.

  • One only has to take a look at the affiliation of the authors to better understand why such a study was conducted in the first place.

    1 Institute of Social Medicine, Epidemiology and Health Economics, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universitaät zu Berlin, Berlin, Germany.
    2 Department of Internal and Integrative Medicine, Immanuel Hospital Berlin, Berlin, Germany.
    3 Hasso Plattner Institute, Digital Health Center, University of Potsdam, Potsdam, Germany.
    4 Department of Psychology and Psychotherapy, Witten/Herdecke University, Witten, Germany.

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