title: Predicting the onset and persistence of episodes of depression in primary health care. The predictD-Spain study: methodology.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Departamento de Medicina Preventiva, Universidad de Málaga; Unidad de Investigación de Atención Primaria de Málaga (redIAPP, grupo SAMSERAP), Centro de Salud El Palo, Spain. JABELLON@terra.es
authors.forename: Juan Angel
authors.initials: JA
authors.lastname: Bellón
authors.forename: Berta
authors.initials: B
authors.lastname: Moreno-Küstner
authors.forename: Francisco
authors.initials: F
authors.lastname: Torres-González
authors.forename: Carmen
authors.initials: C
authors.lastname: Montón-Franco
authors.forename: María Josefa
authors.initials: MJ
authors.lastname: GildeGómez-Barragán
authors.forename: Marta
authors.initials: M
authors.lastname: Sánchez-Celaya
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Díaz-Barreiros
authors.forename: Catalina
authors.initials: C
authors.lastname: Vicens
authors.forename: Juan
authors.initials: J
authors.lastname: de Dios Luna
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Cervilla
authors.forename: Blanca
authors.initials: B
authors.lastname: Gutierrez
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Martínez-Cañavate
authors.forename: Bárbara
authors.initials: B
authors.lastname: Oliván-Blázquez
authors.forename: Ana
authors.initials: A
authors.lastname: Vázquez-Medrano
authors.forename: María Soledad
authors.initials: MS
authors.lastname: Sánchez-Artiaga
authors.forename: Sebastia
authors.initials: S
authors.lastname: March
authors.forename: Emma
authors.initials: E
authors.lastname: Motrico
authors.forename: Victor Manuel
authors.initials: VM
authors.lastname: Ruiz-García
authors.forename: Paulette Renée
authors.initials: PR
authors.lastname: Brangier-Wainberg
authors.forename: María
authors.initials: M
authors.lastname: Del Mar Muñoz-García
authors.forename: Irwin
authors.initials: I
authors.lastname: Nazareth
authors.forename: Michael
authors.initials: M
authors.lastname: King
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003866:Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology; D005163:Factor Analysis, Statistical; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011320:Primary Health Care; D011446:Prospective Studies; D012008:Recurrence; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012959:Socioeconomic Factors; D013030:Spain / Q000453:epidemiology; D011795:Surveys and Questionnaires / Q000592:standards*