years of follow-up and young enough for the initial assessment to occur before incipient disease had a material impact on exposures. Data Availability Data from the Baseline Assessment The 500,000 participants were assessed between 2006 and 2010 in 22 assessment centres throughout the UK, covering a variety of different settings to provide socioeconomic and ethnic heterogeneity and urban– rural mix. This ensured a broad distribution across all exposures to allow the reliable detection of generalisable associations between baseline characteristics and health outcomes. The assessment visit comprised electronic signed consent; a selfcompleted touch-screen questionnaire; brief computerassisted interview; physical and functional measures; and collection of blood, urine, and saliva (Table 2).Multiple aliquots of different sample fractions are stored in UK Biobank’s automated laboratory, allowing for a wide range of future assays [10]. Data from Additional Assessments to Enhance Phenotyping UK Biobank is conducting a range of additional phenotyping assessments in all (or large subsets) of the participants. Data are already available both from a detailed dietary web questionnaire [11], completed up to four times by over 200,000 participants, and from the first repeat of the entire baseline assessment in around 20,000 participants [12]. Over the comingmonths and years, further data will become available from: a range of biochemical assays and Invest in ME research (Charity Nr. 1153730) genome-wide genotyping of baseline samples from all participants;Web-based questionnaires to assess specific characteristics in more detail (e.g., cognitive function, occupational history); and, in subsets of 100,000 participants, collection of data from physical activity monitors and multi-modal imaging (Table 3). Data from Longitudinal Follow-Up for Health-Related Outcomes Follow-up is conducted chiefly through linkages to routinely available national datasets. Data are already available on over 8,500 deaths, over 75,000 prevalent and incident cancers, and over 600,000 hospital admissions, while linkages are planned to a range of other datasets, including primary care, cancer screening data, and disease-specific registers. In addition, to reduce misclassification and increase biological specificity of health outcomes, UK Biobank is developing methods for accurate identification and detailed phenotyping of outcomes in a range of disease areas. Initial ascertainment of outcomes with electronic and semi-automated sources will be supplemented by more intensive methods (e.g., retrieval of case records, imaging data, or banked tissue samples) for validation and subclassification (Table 3). Online Open Access to Researchers Many cohort studies have mechanisms for sharing data with external researchers on a collaborative basis, but relatively few have arrangements for open access to the data without any need for collaboration, and even fewer have been established from the outset with the intention of making the entire resource available to the www.investinme.org Page 23 of 56
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