Study protocol

A randomised controlled trial of the effects of a web-based PSA decision aid, Prosdex. Protocol

Rhodri Evans¹ , Glyn Elwyn¹ , Adrian Edwards¹ , Robert Newcombe¹ , Paul Kinnersley¹ , Pat Wright² , Jeff Griffiths³ , Joan Austoker⁴ and Richard Grol⁵

¹  Department of Primary Care and Public Health, Cardiff University, Wales, UK

²  School of Psychology, Cardiff University, Wales, UK

³  School of Mathematics, Cardiff University, Wales, UK

⁴  Cancer Research UK Primary Care Education Research Group, Division of Public Health and Primary Health Care, University of Oxford, Oxford, UK

⁵  Centre for Quality of Care Research (WOK), Radboud University, Nijmegen, Netherlands

author email corresponding author email

BMC Family Practice 2007, 8:58doi:10.1186/1471-2296-8-58

Published:	4 October 2007

Abstract

Background

Informed decision making is the theoretical basis in the UK for men's decisions about Prostate Specific Antigen (PSA) testing for prostate cancer testing. The aim of this study is to evaluate the effect of a web-based PSA decision-aid, Prosdex, on informed decision making in men. The objective is to assess the effect of Prosdex on six specific outcomes: (i) knowledge of PSA and prostate cancer-related issues – the principal outcome of the study; (ii) attitudes to testing; (iii) decision conflict; (iv) anxiety; (v) intention to undergo PSA testing; (vi) uptake of PSA testing. In addition, a mathematical simulation model of the effects of Prosdex will be developed.

Methods

A randomised controlled trial with four groups: two intervention groups, one viewing Prosdex and the other receiving a paper version of the site; two control groups, the second controlling for the potential Hawthorn effect of the questionnaire used with the first control group. Men between the ages of 50 and 75, who have not previously had a PSA test, will be recruited from General Practitioners (GPs) in Wales, UK. The principal outcome, knowledge, and four other outcome measures – attitudes to testing, decision conflict, anxiety and intention to undergo testing – will be measured with an online questionnaire, used by men in three of the study groups. Six months later, PSA test uptake will be ascertained from GP records; the online questionnaire will then be repeated. These outcomes, and particularly PSA test uptake, will be used to develop a mathematical simulation model, specifically to consider the impact on health service resources.

Trial registration

Current Controlled Trial: ISRCTN48473735.