Same information, different decisions: the influence of evidence on the management of hypertension in the elderly

Abstract

Background: Evidence-based medicine requires general practitioners (GPs) to act upon the results of clinical trials. Clinical trial evidence may be difficult to understand and apply in practice.

Aim: To investigate whether GPs were unduly influenced in managing hypertension in the elderly by the ways in which benefits of trial results were presented, and to establish whether their current treatment of an elderly hypertensive patient was broadly in line with recent clinical trial evidence.

Method: Seventy-three GPs attending a refresher course were given a written questionnaire containing data from one clinical trial of treatment of hypertension in the elderly presented in four different ways (absolute risk reduction, relative risk reduction, difference in event-free patients, and number of patients who had to be treated in order to prevent one clinical event), as if from four different trials. The effect of each presentation on treatment preferences was assessed using Likert scales. The results were analysed to determine whether the method of presentation of results influenced decision making. A clinical scenario was presented to investigate their current treatment preferences in an elderly hypertensive.

Results: All GPs returned completed questionnaires. Relative risk reduction was the only presentation which was significantly different from the others, and was the most likely to influence prescribing. In free-text comments, 75% of GPs admitted having problems understanding statistics commonly found in medical journals. More than 90% conformed with recent clinical trial evidence for the management of hypertension.

Conclusion: GPs were most influenced by relative risk reduction, and were unaware of how the presentation of research results could affect treatment decisions. Most GPs freely admitted to difficulty in comprehending medical statistics. Almost all of the GPs expressed treatment decisions which were broadly in line with clinical evidence.