What has medicine ever done for us? Well, there’s antibiotics. And chemotherapy. And vaccinations. OK, apart from antibiotics, chemotherapy and vaccinations, what has medicine ever done for us?
Not so fast. They’ve helped combat infectious diseases, haven’t they, and, as a result, there’s been a 74 percent decline in mortality rates in developed countries since 1900. Pretty impressive, no?
It’s true. One of the greatest, and unsung, achievements of mankind has been the defeat of 11 major infectious diseases – including cholera, scarlet fever, smallpox, whooping cough and measles – which accounted for 40 percent of all deaths in the United States in 1900. In that year, the death rate stood at around 17 people per 1,000 in the population.
By the late 1940s, the rate had dropped by about 40 percent, to roughly 10 people per 1,000, and it continued to slowly decline through the start of the twenty-first century. Although it’s begun to creep back up, from a minimum of 7.9 people per 1,000 in 2009 to a rate of 8.4 per 1,000 in 2016, this still represents roughly a halving of the death rate since 1900.
If you’d searched earlier than 1900 – which you can do with data from the UK – you’d see that the death rate had started to decline from around the 1850s.
Looking at specific diseases, you’ll see a similar pattern. The death rate from measles in the UK in 1860 was more than 1,000 children per million, and it had dropped to less than 100 per million by 1950, a ten-fold reduction.But an early version of the measles vaccine was introduced only in 1963.
Then there’s whooping cough (pertussis). In 1890, the death rate was around 900 per million children; by 1930, it was down to around 200 per million. But the DTP vaccine was introduced only in 1940.
Scarlet fever was killing around 600 children per million in 1890, which fell to fewer than 100 per million by 1930. But penicillin was introduced only in 1942.
So what’s really caused this sharp decline? It’s a question that has fascinated doctors and medical historians for years. Leading the way was English physician Thomas McKeown, who examined the decline in the death rate in England and Wales over three centuries.
He notes the decline started during the eighteenth century, which he attributes to improvements in the environment, but it became steeper in the second half of the nineteenth century, which was wholly caused by a loosening of the fatal grip of infectious diseases.This drop in infections can be explained by three factors: rising living standards, especially better diet and nutrition, improvements in personal and public hygiene, and a “favorable trend” in the relationship between some micro-organisms and their human hosts.
But, he emphasized, medicine made an insignificant contribution to this decline. The effect of immunization, such as it was, was to restrict smallpox, and this accounted for just 5 percent of the reduction in the death rate.
The fall continued throughout the twentieth century, driven by improving nutrition, better public sanitation and “less certainly” immunization. Nutrition on its own was responsible for half of the drop in death rate, McKeown estimated, with sanitation being responsible for one-sixth, or 16 percent, and immunization and other medical therapies combined responsible for just one-tenth, or 10 percent.1
Warming to the theme, husband-and-wife team John and Sonja McKinlay, both epidemiologists at Boston University, estimated that 92 percent of the decline in the mortality rate had happened in the US by 1950, and agreed with McKeown that medical measures had very little to do with it. In fact, they were even more conservative, estimating that medicine – particularly vaccinations and antibiotics – was responsible for just 1 to 3.5 percent of the decline.2
And they sound a warning that, to today’s ears, sounds prescient. “It is not uncommon today for biotechnological knowledge and specific medical interventions to be invoked as the major reason for most of the modern decline in mortality.”
In other words, medicine and its paraphernalia have taken undue credit for a decline that was caused by other factors, and as a result, it has been rewarded by society with billions of dollars in gratitude.
Or as medical historian Ren Dubos put it in his seminal 1959 book Mirage of Health, “When the tide is receding from the beach it is easy to have the illusion that one can empty the ocean by removing water with a pail.”
The McKinlay Study, as it became known, was required reading in medical school for many years until it was quietly removed. That would have told aspiring doctors that medicine really hasn’t ever done much for us.
References
1 Popul Stud (Cambridge), 1975; 29: 391-422
2 Milbank Mem Fund Q Health Soc, 1977; 55: 405-28
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