title: Linking of primary care records to census data to study the association between socioeconomic status and cancer incidence in Southern Europe: a nation-wide ecological study.
abstract: BACKGROUND
  Area-based measures of economic deprivation are seldom applied to large medical records databases to establish population-scale associations between deprivation and disease.
  
  
  OBJECTIVE
  To study the association between deprivation and incidence of common cancer types in a Southern European region.
  
  
  METHODS
  Retrospective ecological study using the SIDIAP (Information System for the Development of Research in Primary Care) database of longitudinal electronic medical records for a representative population of Catalonia (Spain) and the MEDEA index based on urban socioeconomic indicators in the Spanish census. Study outcomes were incident cervical, breast, colorectal, prostate, and lung cancer in 2009-2012. The completeness of SIDIAP cancer recording was evaluated through linkage of a geographic data subset to a hospital cancer registry. Associations between MEDEA quintiles and cancer incidence was evaluated using zero-inflated Poisson regression adjusted for sex, age, smoking, alcoholism, obesity, hypertension, and diabetes.
  
  
  RESULTS
  SIDIAP sensitivity was 63% to 92% for the five cancers studied. There was direct association between deprivation and lung, colorectal, and cervical cancer: incidence rate ratios (IRR) 1.82 [1.64-2.01], IRR 1.60 [1.34-1.90], IRR 1.22 [1.07-1.38], respectively, comparing the most deprived to most affluent areas. In wealthy areas, prostate and breast cancers were more common: IRR 0.92 [0.80-1.00], IRR 0.91 [0.78-1.06]. Adjustment for confounders attenuated the association with lung cancer risk (fully adjusted IRR 1.16 [1.08-1.25]), reversed the direction of the association with colorectal cancer (IRR 0.90 [0.84-0.95]), and did not modify the associations with cervical (IRR 1.27 [1.11-1.45]), prostate (0.74 [0.69-0.80]), and breast (0.76 [0.71-0.81]) cancer.
  
  
  CONCLUSIONS
  Deprivation is associated differently with the occurrence of various cancer types. These results provide evidence that MEDEA is a useful, area-based deprivation index for analyses of the SIDIAP database. This information will be useful to improve screening programs, cancer prevention and management strategies, to reach patients more effectively, particularly in deprived urban areas.
authors.affiliation: Research Unit, Family Medicine, Girona, Spain, and Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalunya, Spain; Translab Research Group, Department of Medical Sciences, School of Medicine, University of Girona, Catalunya, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Garcia-Gil
authors.affiliation: Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalunya, Spain.
authors.forename: Josep-Maria
authors.initials: JM
authors.lastname: Elorza
authors.affiliation: Cancer Prevention Unit and Cancer Registry, Department of Epidemiology and Evaluation, Hospital del Mar, Barcelona, Catalunya, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Banque
authors.affiliation: Research Unit, Family Medicine, Girona, Spain, and Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalunya, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Comas-Cufí
authors.affiliation: Research Unit, Family Medicine, Girona, Spain, and Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalunya, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Blanch
authors.affiliation: Primary Care Services, Girona, Spain, and Catalan Institute of Health (ICS), Catalunya, Spain.
authors.forename: Rafel
authors.initials: R
authors.lastname: Ramos
authors.affiliation: Primary Care Information System, Catalan Institute of Health (ICS), Catalunya, Spain.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Méndez-Boo
authors.affiliation: Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalunya, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Hermosilla
authors.affiliation: Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalunya, Spain.
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Bolibar
authors.affiliation: Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalunya, Spain; Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Prieto-Alhambra
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D019352:Censuses; D016208:Databases, Factual; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology*; D011320:Primary Health Care; D012189:Retrospective Studies; D017678:Sex Distribution; D012923:Social Class; D013030:Spain / Q000453:epidemiology; D055815:Young Adult