title: Heavy lifting at work and risk of ischemic heart disease: protocol for a register-based prospective cohort study.
abstract: BACKGROUND
  There are theoretical grounds to suspect that heavy lifting at work is an important risk factor for ischemic heart disease (IHD). However the relationship has not been sufficiently acknowledged by empirical studies. Positive and statistically significant associations have been found in studies that utilize self-reported exposure data. Such studies are, however, prone to reporting bias. All else equal, people with a poor cardiovascular fitness/health may have a higher propensity to perceive their work environment as heavy.
  
  
  OBJECTIVE
  The study described in the present protocol aims to investigate the relationship between heavy lifting at work and IHD by use of material and methods that are free from reporting bias.
  
  
  METHODS
  This is a register-based prospective cohort study. Male blue-collar workers in Denmark will be identified and followed through national registers, from 2001-2010, for hospital treatment or death due to IHD. Relative rates of IHD between "workers in occupations likely to involve heavy lifting" and "other blue-collar workers" will be estimated through Poisson regression.
  
  
  RESULTS
  Results are expected to be ready in mid-2015.
  
  
  CONCLUSIONS
  Since this is not a randomized study, it cannot confirm etiological hypotheses. It may, however, confirm that employment in occupations that involve heavy lifting is a predictor for IHD and thereby lend support to the hypothesis of a causal relationship.
authors.affiliation: National Research Centre for the Working Environment, Denmark, Copenhagen, Denmark. hha@nrcwe.dk.
authors.forename: Harald
authors.identifier: http://orcid.org/0000-0003-0687-0499
authors.initials: H
authors.lastname: Hannerz
authors.forename: Andreas
authors.identifier: http://orcid.org/0000-0003-4825-5697
authors.initials: A
authors.lastname: Holtermann
keywords: cardiovascular disease; cohort study; manual work; occupational health