In 2001 the National Institute for Clinical Excellence (NICE) was asked to issue guidance for England and Wales on the use of photodynamic therapy (PDT). This process has been protracted, partly because of a dispute over the magnitude of beneficial effect. This article examines the origins of the debate about the true treatment effect size for PDT with verteporfin.
West Midlands Health Technology Assessment Group, Department of Public Health and Epidemiology, University of Birmingham, Edgbaston, Birmingham, UK. c.a.meads@bham.ac.uk
