How to read a paper. Papers that report drug trials

If you prescribe drugs, the pharmaceutical industry is interested in you and is investing a staggering sum of money trying to influence you. The most effective way of changing the prescribing habits of a clinician is through personal representatives (known in Britain as “drug reps” and in North America as “detailers”), who travel round with a briefcase full of “evidence” in support of their wares.1 Pharmaceutical “reps” do not tell nearly as many lies as they used to (drug marketing has become an altogether more sophisticated science), but they have been known to cultivate a shocking ignorance of basic epidemiology and clinical trial design when it suits them.2 It often helps their case, for example, to present the results of uncontrolled trials and express them in terms of before and after differences in a particular outcome measure.3 The recent correspondence in the Lancet and BMJ on placebo effects should remind you why uncontrolled before and after studies are the stuff of teenage magazines, not hard science.4 5 6 7 8 9 10 11 12 Sackett and colleagues have argued that before giving a drug to a patient the doctor should: #### Summary points Pharmaceutical “reps” are now much more informative than they used to be, but they may show ignorance of basic epidemiology and clinical trial design The value of a drug should be expressed in terms of safety, tolerability, efficacy, and price The efficacy of a drug should ideally be measured in terms of clinical end points that are relevant to patients; if surrogate end points are used they should be valid Promotional literature of low scientific validity (such as uncontrolled before and after trials) should not be allowed to influence practice