Even Immortality

Thomas Laqueur

The Greatest Benefit to Mankind: A Medical History of Humanity from Antiquity to the Present by Roy Porter
HarperCollins, 833 pp, £24.99, February 1999, ISBN 0 00 637454 9

No one should take comfort from the title of Roy Porter’s shaggy masterpiece of a history of medicine. ‘The Greatest Benefit to Mankind’ – the phrase is Dr Johnson’s – begs for a question-mark, a rising inflection of incredulity, if not outright disbelief. Porter is too ebullient, too much of an optimist, too little of a polemicist to supply the Rousseauian rejoinder: ‘An art more pernicious to men than all the ills it pretends to cure’. But no one who follows Simon Schama’s advice helpfully prescribed in the blurb – ‘take a dose of the book at least once a day and retire early to bed’ – will sleep easy.

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Vol. 21 No. 15 · 29 July 1999 » Thomas Laqueur » Even Immortality (print version)
Pages 3-9 | 8291 words

Letters

From Paul Taylor

Thomas Laqueur writes (LRB, 29 July) that a medical textbook becomes obsolete within five years. In fact the information in a textbook may be out of date long before the book is published. The routine use of streptokinase in myocardial infarction, for example, began to be advised in textbooks in 1987, 13 years after an analysis of the published clinical trials would have revealed clear and compelling evidence to support its use. No one expects their GP to stay abreast of a literature in which a new paper is published, on average, every 15 seconds. On the other hand, any patient with Internet access can quickly obtain the results of all the latest research pertinent to their condition. The consequences of this for the doctor-patient relationship may be one of the things that future generations examine when they study medicine at the end of the 20th century.

Statistical textbooks age less rapidly. According to those on my shelf, pace Mark Greenberg and Macneil of Barra, the reliability of a medical test is not a measure of its capacity to differentiate between sick and healthy patients but of the extent to which that capacity is vulnerable to error. Greenberg makes it clear that he is actually talking about the sensitivity and specificity of medical tests. Macneil appears to use the term to refer to predictive value. The key difference between sensitivity and predictive value is exactly the thing that interests Greenberg: the impact of the prior probability of having the disease. In clinical terms, its prevalence. The point is that you can only calculate the predictive value of a test for a given prevalence, and the prevalence of exposure to nerve gas, to use Macneil's example, will vary widely between different groups of patients. I'd be happier with Dr Greenberg.

Paul Taylor
University College London