Objectives/methods: External validity depends on the sample in terms of its size and representativeness. Across Europe researchers' access to patients, is increasingly constrained by data protection and research governance legislation. We report experience and findings from an UK study and discuss success of different recruitment strategies: identification by GPs and identification in hospital with recruitment in both cases in the community.
Results: Our sample size was 200 but we recruited only 109 despite considerable time and resources dedicated to recruitment and a number of advantages such as experience, local reputation and champions. The ethics committees' interpretation of regulations presented multiple "moving targets" and practitioner control over sample identification and selection were significant hurdles in accessing patients. In primary care, 12 recruitment rounds with 1871 contacts resulted in 78 nominations. There was significantly poorer recruitment after the implementation of new data protection legislation (5.2-1.8%; difference=3.4%; CI diff=1.6 to 4.9). Recruitment from hospital was more efficient. 237 patients identified; 191 eligible; 46 GP refused; 145 approached, 73 (50%) recruited. GPs' reasons for declining access to patients were on valid ineligibility criteria in about 1/3 of cases. In 2/3s of cases reasons are perhaps less justifiable and possibly over protective, "I do not think he is a suitable patient".
Conclusions: Gate keeping responsibilities, both statutory and as personally interpreted, represent considerable challenges for researchers seeking representative samples. Whilst intentions may be laudable, implementation has had a detrimental effect on research and thus ultimately provision of health care. Alliances with practitioners, patients, public and politicians need to be developed to facilitate research.