Predicting the onset and persistence of episodes of depression in primary health care. The predictD-Spain study: Methodology Bellón Saameño, Juan Ángel Moreno-Küstner, Berta Torres González, Francisco Montón-Franco, Carmen Gilde Gómez-Barragán, María Josefa Sánchez-Celaya, Marta Díaz-Barreiros, Miguel Ángel Vicens, Catalina Luna Del Castillo, Juan De Dios Cervilla Ballesteros, Jorge A. Gutiérrez Martínez, Blanca Martínez-Cañavate López-Montes, Teresa Oliván-Blázquez, Bárbara Vázquez-Medrano, Ana Sánchez-Artiaga, María Soledad March, Sebastia Motrico, Emma Ruiz-García, Víctor Manuel Brangier-Wainberg, Paulette Muñoz-García, María del Mar Nazareth, Irwin King, Michael PredictD Group Common mental disorders Population based cohort Major depression Risk factors Life events Psychiatric disorder Generalized anxiety Different cultures Physical health Social support Background: The effects of putative risk factors on the onset and/or persistence of depression remain unclear. We aim to develop comprehensive models to predict the onset and persistence of episodes of depression in primary care. Here we explain the general methodology of the predictD-Spain study and evaluate the reliability of the questionnaires used. Methods: This is a prospective cohort study. A systematic random sample of general practice attendees aged 18 to 75 has been recruited in seven Spanish provinces. Depression is being measured with the CIDI at baseline, and at 6, 12, 24 and 36 months. A set of individual, environmental, genetic, professional and organizational risk factors are to be assessed at each follow-up point. In a separate reliability study, a proportional random sample of 401 participants completed the test-retest (251 researcher-administered and 150 self-administered) between October 2005 and February 2006. We have also checked 118,398 items for data entry from a random sample of 480 patients stratified by province. Results: All items and questionnaires had good test-retest reliability for both methods of administration, except for the use of recreational drugs over the previous six months. Cronbach's alphas were good and their factorial analyses coherent for the three scales evaluated (social support from family and friends, dissatisfaction with paid work, and dissatisfaction with unpaid work). There were 191 (0.16%) data entry errors. Conclusion: The items and questionnaires were reliable and data quality control was excellent. When we eventually obtain our risk index for the onset and persistence of depression, we will be able to determine the individual risk of each patient evaluated in primary health care. 2014-07-29T12:05:59Z 2014-07-29T12:05:59Z 2008 info:eu-repo/semantics/article Bellón, J.A.; et al. Predicting the onset and persistence of episodes of depression in primary health care. The predictD-Spain study: Methodology. BMC Public Health, 8: 256 (2008). [http://hdl.handle.net/10481/32817] 1471-2458 http://hdl.handle.net/10481/32817 10.1186/1471-2458-8-256 eng info:eu-repo/semantics/openAccess Biomed Central