Do drug companies spend the most money to promote the most useless drugs?/ CMAJ

Drug companies spent the most money to promote the most useless drugs, according to the following study in the Canadian Medical Association Journal:

The relation between promotional spending on drugs and their therapeutic gain: a cohort analysis
Joel Lexchin MSc MD

Abstract

Background: Whether drug promotion helps or hinders appropriate prescribing by physicians is debated. This study examines the most heavily promoted drugs and the therapeutic value of those drugs to help determine whether doctors should be using promo- tional material to inform themselves about drugs.
Methods: Lists were constructed of the 50 most heavily promoted drugs (amount of money spent on journal advertisements and vis- its by sales representatives) and the 50 top-selling drugs (by dollar value) for 2013, 2014 and 2015. Therapeutic gain was determined by examining ratings from the Patented Medicine Prices Review Board and the French drug bulletin Prescrire International and was categorized as major, moderate or little to none. For each of the 3 years, the number of drugs in the 3 therapeutic categories for drugs in both groups was compared. The amount and proportion of money spent on promotion for drugs in each of the 3 therapeutic categories for the 3 years was also determined.
Results: Therapeutic ratings were available for 42 of 79 of the most heavily promoted drugs over the 3 years and for 40 of 61 of the top-selling drugs. Nearly all the money spent on promotion in each of the 3 years went to drugs with little to no therapeutic gain. The distribution of therapeutic gain for drugs in both groups was statistically significantly different only in 2013 (p = 0.04).
Interpretation: Most of the money spent on promotion went to drugs that offer little to no therapeutic gain. This result calls into ques- tion whether doctors should read journal advertisements or see sales representatives to acquire information about important medical therapies. 

Correspondence to: Joel Lexchin, jlexchin@yorku.ca CMAJ Open 2017. DOI:10.9778/cmajo.20170089