One of the favourite arguments of proponents of so-called alternative medicine (SCAM) is that conventional medicine is amongst the world’s biggest killers. The argument is used cleverly to discredit conventional medicine and promote SCAM. It has been shown to be wrong many times, but it nevertheless is much-loved by SCAM enthusiasts and thus refuses to disappear. Perhaps this new and important review might help instilling some realism into this endless discussion? Here is its abstract:

Objective To systematically quantify the prevalence, severity, and nature of preventable patient harm across a range of medical settings globally.

Design Systematic review and meta-analysis.

Data sources Medline, PubMed, PsycINFO, Cinahl and Embase, WHOLIS, Google Scholar, and SIGLE from January 2000 to January 2019. The reference lists of eligible studies and other relevant systematic reviews were also searched.

Review methods Observational studies reporting preventable patient harm in medical care. The core outcomes were the prevalence, severity, and types of preventable patient harm reported as percentages and their 95% confidence intervals. Data extraction and critical appraisal were undertaken by two reviewers working independently. Random effects meta-analysis was employed followed by univariable and multivariable meta regression. Heterogeneity was quantified by using the I2 statistic, and publication bias was evaluated.

Results Of the 7313 records identified, 70 studies involving 337 025 patients were included in the meta-analysis. The pooled prevalence for preventable patient harm was 6% (95% confidence interval 5% to 7%). A pooled proportion of 12% (9% to 15%) of preventable patient harm was severe or led to death. Incidents related to drugs (25%, 95% confidence interval 16% to 34%) and other treatments (24%, 21% to 30%) accounted for the largest proportion of preventable patient harm. Compared with general hospitals (where most evidence originated), preventable patient harm was more prevalent in advanced specialties (intensive care or surgery; regression coefficient b=0.07, 95% confidence interval 0.04 to 0.10).

Conclusions Around one in 20 patients are exposed to preventable harm in medical care. Although a focus on preventable patient harm has been encouraged by the international patient safety policy agenda, there are limited quality improvement practices specifically targeting incidents of preventable patient harm rather than overall patient harm (preventable and non-preventable). Developing and implementing evidence-based mitigation strategies specifically targeting preventable patient harm could lead to major service quality improvements in medical care which could also be more cost effective.


One in 20 patients is undoubtedly an unacceptably high proportion, but it is nowhere close to some of the extraordinarily alarming claims by SCAM enthusiasts. And, as I try regularly to remind people, the harm must be viewed in relation to the benefit. For the vast majority of conventional treatments, the benefits outweigh the risks. But, if there is no benefit at all – as with some form of SCAM – a risk/benefit balance can never be positive. Moreover, many experts work hard and do their very best to improve the risk/benefit balance of conventional healthcare by educating clinicians, maximising the benefits, minimising the risks, and filling the gaps in our current knowledge. Do equivalent activities exist in SCAM? The answer is VERY FEW?

22 Responses to One in 20 patients is exposed to preventable harm

  • Interesting…

    diagnosis (16%, 11% to 21%, I2=98%)

      • ” But, if there is no benefit at all – as with some form of SCAM – a risk/benefit balance can never be positive.”

        I don’t agree with that statement.

        n many cases the patient, at a minimum will have the benefit from the placebo effect. This will tip the scales towards a positive risk/reward benefit. From my experience, many times the risk/reward from allopathic medicine is not worth the risk.

        I personally have benefited from CAM and plant based medicine and preventative medicine. Conversely, me and my family have suffered (at times) from science based medicine. So why would I confine myself to one only ?

        • “I don’t agree with that statement”

        • @RG


          Do you agree with this statement?

        • “[I]n many cases the patient, at a minimum will have the benefit from the placebo effect.”

          The same effect can be achieved quite legitimately by various talking therapies for example, or counselling. Alternative therapies make a virtue out of lying to patients, pretending customers are getting more than placebo. This has lead to vulnerable patients putting their faith in it for things that can’t be helped by placebo such as cancer and suffering or dying as a result.

          “I personally have benefited from CAM and plant based medicine and preventative [sic] medicine.”

          Much of science-based medicine is plant based, some herbal products have a measurable effect in the living body and preventive medicine isn’t alternative medicine, it’s mainstream. Your statement says nothing about alternative medicine.

          Health practitioners who really care about patients will use the sort of paper described as an opportunity to refine and improve treatment and patient care. CAM practitioners see them simply as a marketing opportunity. Very cynical and a sure sign CAM practitioners have no understanding of science.


  • Gentlemen – you may have noticed a recent stream of reports concerning conventional health care ‘mistakes’ and ‘errors’ – but you seem to turn a blind eye on this forum. Here is just one tragic case of a young mum who has been left ‘traumatised’ by incompetent medical doctors:

    You take delight in ‘exposing’ so called SCAM practices, but they are relatively harmless compared to the shocking carnage that is inflicted on patients within the NHS.

    • FIRST: there are also many gentle woman here
      Second: this post is addressing the problem of risks of conventional medicine
      THIRD: normally we focus of alt med/SCAM on this blog.

    • Again. for the sake of openness and transparency, would you like to give the name you may have used previously to comment here?

    • Mary

      As ever. That airplanes occasionally crash does not validate magic carpets.

      The misdiagnosis was picked up by internal audit. And admitted.

      Show us how many times AltMed does this.

      Oh. You can’t. Because they don’t.

      Run along, now. There’s a good Sandra.

      • Hospital in Midlands to Sarah Boyle, 28:
        — after she was told she had triple negative breast cancer, treated he mistakenly with chemo, and them lopped off both breast.

        ” we’re sorry, but we promise that won’t happen to you again”

        • you don’t need to convince us that you have still not understood the difference between evidence and anecdote; we know it only too well!

          • Evidence ?? … oh yes Edzard, there will be plenty of factual evidence to provide the Medical Malpractice Court to accompany her anecdote

          • there will be plenty of factual evidence to provide the Medical Malpractice Court to accompany her anecdote

            I don’t think there is a Medical Malpractice Court in the UK.

            However, if Mrs Boyle does pursue a claim in the Civil Court, the standard of evidence required in order to award her damages is “on the balance of probabilities”, i.e. 1 in 2. This is a very low standard of evidence, equivalent to 0-sigma. By comparison, physicists require a standard of 5-sigma before they will accept the results of an experiment, which is about 1 in 3.5 million.

            Since the hospital has already admitted liability the only thing the Court has to decide is the quantum, i.e. the amount of damages, and as this is calculated by a fairly standard formula the hospital will probably offer her an equivalent or slightly larger amount to avoid the expense of a Court case.

            The amount is made up of loss of earnings, cost of care, loss of amenity, loss of life expectancy, pain and suffering and cost of looking after dependents (e.g. children). Of these, loss of earnings is likely to be the largest factor. As far as we know she has not been permanently disabled or maimed, and is not requiring additional private medical care, so loss of amenity doesn’t factor here. She may have an increased risk of heart disease or a future cancer as a result of her treatment, but I wouldn’t have thought that this would make a very great impact on her life expectancy. Since pain and suffering are so subjective, the Courts have a standard scale of damages and actually don’t don’t place a very high value on this (a few thousand pounds at most).

            Of course if she is able to demonstrate that the experience has left her unable to work than the damages could be equivalent to her future earnings, as as she is only 28 potentially that could be a lot of money, but this would depend on what she did for a living before the event.

        • “Hospital in Midlands to Sarah Boyle, 28:
          — after she was told she had triple negative breast cancer, treated he mistakenly with chemo, and them lopped off both breast. ”

          Disgusting (though, sadly, not surprising) that you are using this tragedy as a point-scoring exercise and using such trivialising language too.


        • So then, RG. How would you diagnose breast cancer? You’re critical of those who do via the standard methods so presumably you are able to postulate a credible alternative.


          You can’t, can you.

          Run along, then.

    • In the past hundred years
      – Life expectancy has almost doubled
      – Child mortality has dropped from 15%-25% to < 0.5%
      – Ever more ailments can be cured or at least treated to be bearable/manageable.

      Now please tell us whom we have to thank for this: regular doctors, or traditional/alternative practitioners.

  • Richard

    To a large extent, people are living longer. I wouldn’t credit Western Medical Science for all of that, some of it yes.
    Safer cars, seat belt laws, smoke alarms in homes, better communications, health consciousness, government programs… blah blah.

    That said, much of the older population is not feeling well, and not in good health. Life is extended, but quality of life ? I dunno, alot of pill popping….. hmmm.

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