Cohort profile: the Caerphilly health and social needs electronic cohort study (E-CATALyST).

The Caerphilly Health and Social Needs study was established to inform and support collaborative multiagency working on reducing inequalities in health and to investigate neighbourhood influences on mental health. Initially, we collated a robust small-area multiagency dataset of contextual health determinants and outcomes from routine sources and sharing of data between the National Health Service and Caerphilly county borough council. These data were widely used in local joint planning to improve health and reduce health inequalities. Secondly, we carried out a baseline population questionnaire survey, collecting data from 10 892 (60.6%) respondents aged 18-74 years on a wide range of socio-economic, lifestyle, health and housing factors and perceptions of the local neighbourhood, including access to services, social cohesion and neighbourhood quality. We carried out wave 2 of the survey after 7 years with responses from 4558 (50.2%) participants to the same range of questions. We developed the study into an electronic cohort, linking all 17 979 sampled participants aged 18-74 years to mortality and hospital admission records with 10-year follow-up and full recording of migration both within and out of the borough. Readers with an interest in collaborative use of the data should contact Professor David Fone, Principal Investigator.