The reason its being done over a fairly long period of time (2 years for recruitment, carrying out all the testing and collection of all the data and a further 2 for analysis, drafting, review, touting round journals etc) is to ensure that they are able to recruit enough participants. They are only looking for 40 people with CRPS so its a small scale trial. The eligibility criteria are also extremely wide which will aid the likelihood of recruiting the necessary numbers - they could hardly be any wider!!