Evidence-based medicine and hypertension

Background Evidence-based medicine (EBM) has been propagated as a revolutio nary development which will improve the quality of clinical decision-making and guideline development Historically it follows an early 19th-century Fr ench attempt to introduce mathematical analysis into clinical practice. Thi s met with resistance from both clinicians and scientists and was only acce pted in more recent times with the development of clinical epidemiology and clinical trials. Nature of EBM EMB claims to utilize the best available evidence to reach sc ientific conclusions, rejecting the appeal to expert authority, This involv es a hierarchy of sources which places large controlled trials at the apex. Less value is attributed to arguments from clinical observation or pathoph ysiology, Systematic reviews and meta-analyses of trials therefore provide the strongest evidence for clinical decisions. The concept of evidence The approach advocated in EBM is an over-simplifica tion of the process of clinical thinking which involves interpretation and synthesis of relevant evidence from all sources and extrapolation to the cl inical situation. In this process, there is no hierarchy evidence. The rela tive value given to any particular evidence depends more upon its relevance and persuasiveness than the category to which it belongs. Discussion and d ebate amongst informed 'experts' is an integral feature of this process at each stage. Impact of EBM Although advocates of EBM acknowledge the contribution of all forms of evidence, the differential value attached to different sources ha s led to naive and simplistic attempts to omit the traditional processes of interpretation, synthesis and extrapolation and to draw wide-ranging concl usions from trial data without adequate scientific discussion. (C) Lippinco tt Williams & Wilkins.