Some drugs yield more than one benefit. For instance, Beta blockers have antihypertensive, antianginal, and antiarrhythmic effects. They also have more than one adverse effect. So we can talk about their benefits and harms. It’s all to do with how you count.

The Danish philologist Otto Jespersen expounded the concept of count and non-count nouns in an unpublished lecture to the Copenhagen Academy of Sciences in 1911. As he explained in The Philosophy of Grammar (1924), you can form plurals if you can collect two things alike. For example, two bananas (two of the same thing). Or two fruits, an apple and an orange (two of the same kind). But we have no plural word for a journal plus a stethoscope, except to call them two objects, and certainly no plural word for a journal plus health care.

Music, traffic, and tact cannot be counted; arm, leg, and eye can—at least in English; in Hungarian the word for any pair of body parts is singular; one eye is referred to as a half eye. Then “you” in English denotes both singular and plural (“ye” having disappeared), while the French have “tu” and “vous.” “Peut-on tutoyer?” a student asked her supervisor; the reply was stony: “Si vous voulez.” Some nouns have it both ways, depending on meaning. Chocolates in a box are countable—two chocolates, a few chocolates, many chocolates (but who’s counting?). Chocolate in a bar is not—much chocolate, little chocolate, less chocolate. Morbidity (sickness) is not countable, but comorbidities means diseases; competency (ability) is not countable, but “competencies” means things people can do. Both plurals are relatively new uses.

Now “harm” has two meanings, injury and an injury. And the countable sense has as long a pedigree as the uncountable one. Harms are referred to in a 10th century poem, Genesis, wrongly attributed to Caedmon: “Ealle synt uncre hearmas gewrecene.” Shakespeare uses the noun harm about 90 times, and 14 of those are plural. In The Taming of the Shrew, a messenger tells Christopher Sly that his doctors “thought it good you hear a play / And frame your mind to mirth and merriment, / Which bars a thousand harms and lengthens life.” And Shakespeare knew his count from his non-count: “She hath more hair than wit and more faults than hairs,” says the Veronese clown, Lance, about his sweetheart. However much hair she had, she doesn’t sound like a great catch.

Drugs are prescribed because of their potential benefits, but in every case there are risks of harms; before prescribing, the former should be weighed against the latter. This is commonly called assessing the “benefit to risk ratio.” But benefit and risk are non-comparable: one is an actual outcome, the other a chance of one. Benefits are properly balanced by harms. However, the two are incommensurate and cannot be combined into a ratio. One should therefore talk about the benefit to harm balance, which is a complex function of the seriousness of the problem to be treated, the efficacy and safety of the drug to be used, and the efficacy and safety of other available drugs.

And that is why we have called this special issue of the BMJ “Balancing benefits and harms in health care.”

Jeff Aronson clinical pharmacologist, Oxford

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