||Trials in primary care are no
different from those in secondary or tertiary care in terms of their lack of success in
recruiting all patients with the disease of interest.(Peto
1993) Similarly, trials in any setting are rarely fully representative
with respect to both patient and disease related characteristics. Such
limitations do not invalidate the use of the randomised controlled trial. They
merely require additional work to be undertaken to establish the effect of the
intervention on the total population.