A pill in every mouth

What percentage of American adults are suffering from one or more of these eight diseases, based on pharmaceutical industry and awareness-group claims?

Condition	Claimed prevalence in adults	Source
	(percent)
Restless legs syndrome	10	http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0030170
Irritable bowel syndrome	20	Moynihan and Cassels, Selling Sickness
Bipolar disorder	5	http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0030185
Attention deficit disorder	4	Selling Sickness
Social anxiety disorder	13	Selling Sickness
Erectile dysfunction	52	http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0030132
Female sexual dysfunction	43	http://bmj.bmjjournals.com/cgi/content/full/326/7379/45?ijkey=detpYa.V5DKsM
Sleep disorders	75	http://www.newscientist.com/article.ns?id=mg18925391.300&print=true

First, take the proportion of people who do not have each individual condition (e.g., for restless legs, 1 - .10 = .90, or 90% who don't have it).

Assuming that your chances of having one of these conditions does not affect your chances of having another, and assuming that all conditions except erectile dysfunction and female sexual dysfunction affect the sexes equally, the percentage of adults who have none of them is computed by multiplying together all eight percentages who are free of individual conditions:

For women, that comes to
 (1-.10) x (1-.20) x (1-.05) x (1-.04) x (1-.13) x (1-0) x (1-.43) x (1-.75) =
.90 x .80 x .95 x .96 x .87 x 1.00 x .57 x .25 = .081, or an approximately 8% chance of having none of the conditions.

So (1-.08) = 92% of women would have at least one condition, given claimed figures.

For men,
 (1-.10) x (1-.20) x (1-.05) x (1-.04) x (1-.13) x (1-.52) x (1-0) x (1-.75) =
.90 x .80 x .95 x .96 x .87 x .48 x 1.0 x .25 = .068, or an approximately 7% chance of having none of the conditions.

So (1-.07) = 93% of men would have at least one condition, given claimed figures.

Of course, none of the figures given for individual diseases is precise, so the final percentages of 92 to 93% are anything but precise.  And critics say that if we are considering degrees of affliction that require medication, the figures are wildly exaggerated.  They say far, far fewer people actually need drugs for these problems.

Stan Cox
www.stancox.org