title: Heavy lifting at work and risk of retinal detachment: a population-based register study in Denmark.
abstract: OBJECTIVE
  To investigate the relationship between rhegmatogenous retinal detachment (RRD) and frequent heavy lifting in a Danish working population through national register data.
  
  
  METHODS
  A dynamic cohort of all men aged 20-59 years in Denmark was followed through the Danish Occupational Hospitalisation Register from 1995 to 2010 for diagnosed RRD. Occupational categories were classified according to their potential for heavy lifting in 4 main groups: heavy lifters, manual workers unlikely to be heavy lifters, other manual workers and non-manual workers unlikely to be heavy lifters. The age-standardised rate of diagnosed RRD for heavy lifting occupations was compared with that experienced by the other 3 occupational categories. Rate ratios (RRs) and 95% CIs were estimated through a Poisson regression model adjusted for calendar period and age group.
  
  
  RESULTS
  The highest age-standardised rate of diagnosed RRD was recorded among non-manual workers performing occupational activities unlikely to be associated with heavy lifting (18.0 cases per 100,000 person-years). The RR for workers in jobs expected to entail a high frequency of heavy lifting compared with manual workers whose occupation was unlikely to be associated with heavy lifting was 0.91 (95% CI 0.73 to 1.14), while in comparison with other manual workers, it was 0.93 (95% CI 0.78 to 1.11). The RR compared with non-manual workers in occupations unlikely to entail heavy lifting was 0.51 (95% CI 0.43 to 0.60).
  
  
  CONCLUSIONS
  These findings do not support an association of occupational heavy lifting with diagnosed RRD. The epidemiological evidence for this association is still inconclusive. Future studies should use a more specific measure of exposure to resolve the outstanding uncertainties.
authors.affiliation: Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Curti
authors.affiliation: MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK.
authors.forename: David
authors.initials: D
authors.lastname: Coggon
authors.affiliation: National Research Centre for the Working Environment, Copenhagen, Denmark.
authors.forename: Harald
authors.initials: H
authors.lastname: Hannerz
authors.affiliation: Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mattioli
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D017770:Lifting; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D009790:Occupations; D012042:Registries; D012163:Retinal Detachment / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D014937:Work; D055815:Young Adult