Objectives To investigate the association between occupational lifting and the risk of rhegmatogenous retinal detachment (RRD) using data from a large population of men.
Methods We used data from a national cohort of 49 321 Swedish men conscripted for compulsory military service in 1969–1970. We collected information on surgically treated RRD from the National Patient Register and we followed up the cohort between 1991 and 2009 at ages 40–60 years. Exposure to occupational lifting was assessed by applying a job exposure matrix to occupational data from the 1990 census. Incidence rate ratios (IRRs) and 95% CIs were estimated through Poisson regression models adjusted by degree of myopia, income and education level.
Results We observed 217 cases of RRD in 7 80 166 person-years. In univariate analyses we did not observe an association between occupational lifting and RRD. However, after adjustment for myopia and socioeconomic factors, we found an increased risk of RRD (IRR 2.38, 95% CI 1.15 to 4.93) for subjects in the highest category of exposure compared with those in the lowest one. The incidence rate of RRD among subjects lifting heavy loads at least twice per week, aged between 50 years and 59 years, and affected by severe myopia was as high as 7.9 cases per 1000 person-years, compared with an overall rate of 0.28.
Conclusions Our study supports the hypothesis that heavy occupational lifting is a risk factor for RRD. Information on myopia degree and socioeconomic status is necessary when studying the association between occupational lifting and RRD.
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Contributors AF, DK and TH contributed to the conception and design of the study. KK and TH participated in acquisition of data. AF, DK and TH drafted the manuscript. AF carried out the statistical analysis. SM and KK commented on the draft manuscript. All the authors participated in the interpretation of the findings and read and approved the final version of the manuscript.
Funding This work was supported in part by grant [R01OH 010539] from the U.S. National Institute for Occupational Safety and Health.
Competing interests None declared.
Ethics approval Stockholm’s Regional Ethical Review Board at Karolinska Institutet (reference number 2004/5:9-639/5).
Provenance and peer review Not commissioned; externally peer reviewed.
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