'Real world' pragmatic clinical trials: what are they and what do they tell us?

Although the explanatory clinical therapeutic trial remains the foundation for assessing drug efficacy and is required for licensing purposes, the overall effectiveness of a treatment can be best judged by carefully designed and well conducted pragmatic 'real world' randomized trials. Pragmatic trials seek to inform prescribers and health care planners on the most effective and cost beneficial treatments. Pragmatic trials deserve more attention and should be included in evidence based guidelines for the pharmacological management of common diseases such as asthma and atopy.