Abstract:
Randomised controlled trials (RCTs), although regarded as
the best method for assessing the efficacy of an intervention, have several shoncomings and may be impossible to conduct,
for example in the case of harmful risk factors or aetiological
factors such as smoking4 or schistosomes. Analytical studies such as case-eontrol studies or non-RCT follow-up studies provide alternative approaches for assessing drug or vaccine efficacy, health service8 interventions, as well as the role of risk factors for disease.
