Semmelweis: mortality and benchmarking

Semmelweis in 1860

It concerns me that in my previous post I may have given the impression that I thought that mortality could never be a good indicator of care quality (or, strictly, poor care quality). This is by no means the case: what I’m saying is that mortality figures have to be handled with prudence and there are many areas of care where they are not helpful, if only because mortality is so low.

One of those areas, in the developed world at least, is maternity services. I say in the developed world because in 2008, the maternal mortality rate in the UK was 8.2 per 100,000; in Ghana it was 409 and in Afghanistan it was 1575, so in the latter two countries it is certainly a useful indicator, indeed an indictment of how little we have achieved in improving healthcare across the world.

It used to be a significant indicator in Europe too. In 1846, for example, Professor Ignaz Semmelweis was working in a Viennese hospital in which two clinics provided free maternity services in return for the patient accepting that they would be used for training doctors and midwives. Semmelweis was appalled to discover that there were massively different rates of death from puerperal fever, or childbed fever as it was called, in the two clinics. As the table below shows, the figures over six years showed mortality of just under 10% in the first clinic and just under 4% in the second.

Semmelweis's findings for the two Clinics. Source: Wikipedia

In a fascinating early example of benchmarking, Semmelweis carried out a detailed study of both clinics gradually eliminating any factor that could explain the difference. One possible cause he was able to exclude early on was overcrowding: women were clamouring to get into the second clinic rather than the first, for obvious reasons, so it had a great many more patients.

Eventually, the only difference he could identify was that the first clinic was used for the training of doctors and the second for the training of midwives. And what was the difference? The medical students also took part in dissection classes, working on putrefying dead bodies, and then attended the women in labour without washing their hands. Semmelweis was able to show that with thorough handwashing using a sterilising solution it was possible to get childbed fever deaths down to under 1%.

Unfortunately, his findings weren’t received with cries of joy. On the contrary, since he seemed to be suggesting that the doctors were causing the deaths, he met considerable resistance. Semmelweis died at the age of 47 in a lunatic asylum (though this may not have been related to the reception of his work). It took Louis Pasteur's research and the adoption of the theory of disease transmission by germs for Semmelweis’s recommendations to win widespread acceptance.

This is a striking illustration of the principle that it isn’t enough to demonstrate the existence of a phenomenon and that you have to have a plausible mechanism to propose for it too. Semmelweis had shown the germ-borne spread of disease, but he hadn’t proposed the germ mechanism to explain how it happened.

Still, Semmelweis’s works remains a brilliant use of mortality as an indicator and the use of benchmarking to achieve a breakthrough in the improvement of healthcare. An excellent example of the brilliant use of healthcare information.