Science from both sides – the INTERVAL study

As a regular blood donor, I was intrigued when I was invited to take part in a study on the effects of blood donation frequency. Apparently there is not much solid data on what blood donation intervals (between donations) are safe for the donor. And the recommended guidelines differ significantly around the world.

The INTERVAL trial assessed the effects of different  blood donation intervals. Participants, over 45,000 of them, were randomised to 8, 10, or 12 week intervals for men, and 12, 14, or 16 weeks for women for two years (I was an “8-weeker”). The results have now been published in the Lancet, and make for interesting reading.

The first finding (and I have to say I didn’t realise this was even one of the study aims) was that increasing the frequency also increased the amount of blood donated significantly. Adherence to the study was good, and participants also donated much more than they had in the past two years.

The impact on the health of the participants was what interested me most though. There wasn’t any change in self-reported general wellbeing measures. But “more frequent donation resulted in more donation-related symptoms (eg, tiredness, breathlessness, feeling faint, dizziness, and restless legs, especially among men…)”. And additional donations also led to “lower mean haemoglobin and ferritin concentrations, and more deferrals for low haemoglobin”. So donating very frequently isn’t exactly good for you, which does make sense.

So I was happy to take part, and pleased to read the results. From a quick read of the Lancet article, this seems like a well-designed and analysed study, and importantly large enough to provide robust results on an important topic. If only more of medical science was like this (or indeed any science about humans…).


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