More cases, doctor? Yes please!

The scientific basis of modern clinical practice is founded on the randomised controlled trial [1]. Trials are experimental studies in which two or more selected groups (arms) which may (or may not be) "representative"of the whole population are assigned at random to one or more interventions and sometimes to an inert control (placebo) or compared to standard practice. The idea is that randomisation, if correctly applied to sufficient numbers would spread the effect of confounders equally across all arms of the trial. Randomisation creates the ultimate experimental conditions: whatever differences I observe between arms must be due to the only remaining modifiying factor, i.e. the intervention. This could be a drug, a diagnostic test, a vaccine or even an administrative procedure or clinical pathway. Trials are needed for the registration of new drugs, vaccines and major procedures, although curiously they are not necessary to register commonly used devices such as hip or knee prostheses. As a consequence of the importance of trials a whole new branch of epidemiology (let's call it trialology) was born to study trials, their design, conduct, reporting, synthesis and the implementation of their findings [2-4].