title: The contribution of major risk factors and job strain to occupational class differences in coronary heart disease incidence: the MONICA Brianza and PAMELA population-based cohorts.
abstract: OBJECTIVE
  We investigated the contribution of major coronary heart disease (CHD) risk factors and job strain to occupational class differences in CHD incidence in a pooled-cohort prospective study in northern Italy.
  
  
  METHODS
  2964 men aged 25-74 from four northern Italian population-based cohorts were investigated at baseline and followed for first fatal or non-fatal CHD event (171 events). Standardised procedures were used for baseline risk factor measurements, follow-up and validation of CHD events. Four occupational classes were derived from the Erikson-Goldthorpe-Portocarero social class scheme: higher and lower professionals and administrators, non-manual workers, skilled and unskilled manual workers, and the self-employed. HRs were estimated with Cox models.
  
  
  RESULTS
  Among CHD-free subjects, with non-manual workers as the reference group, age-adjusted excess risks were found for professionals and administrators (+84%, p=0.02), the self-employed (+72%, p=0.04) and manual workers (+63%, p=0.04). The relationship was consistent across different CHD diagnostic categories. Adjusting for major risk factors only slightly reduced the reported excess risks. In a sub-sample of currently employed subjects, adjusting for major risk factors, sport physical activity and job strain reduced the excess risk for manual workers (relative change = -71.4%) but did not substantially modify the excess risks of professionals and administrators and the self-employed.
  
  
  CONCLUSIONS
  In our study, we found higher CHD incidence rates for manual workers, professionals and administrators, and the self-employed, compared to non-manual workers. When the entire spectrum of job categories is considered, the job strain model helped explain the CHD excess risk for manual workers but not for other occupational classes.
authors.affiliation: Dipartimento di Medicina Sperimentale, Università degli Studi dell’Insubria, Varese, Italy. marco.ferrario@uninsubria.it
authors.forename: Marco M
authors.initials: MM
authors.lastname: Ferrario
authors.forename: Giovanni
authors.initials: G
authors.lastname: Veronesi
authors.forename: Lloyd E
authors.initials: LE
authors.lastname: Chambless
authors.forename: Roberto
authors.initials: R
authors.lastname: Sega
authors.forename: Carla
authors.initials: C
authors.lastname: Fornari
authors.forename: Matteo
authors.initials: M
authors.lastname: Bonzini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cesana
mesh_terms: D000328:Adult; D000368:Aged; D003327:Coronary Disease / Q000453:epidemiology*; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology*; D009790:Occupations; D011446:Prospective Studies; D012307:Risk Factors; D012923:Social Class; D014940:Work Schedule Tolerance