P-50 Occupational movements and postures of the neck as risk factors for cervical disc herniation (CDH)

• Published in: Occupational and environmental medicine (London, England) Vol. 78; no. Suppl 1; p. A66
• Main Authors: Petersen, Jonathan, Brauer, Charlotte, Thygesen, Lau, Flachs, Esben Meulengracht, Lund, Christina Bach, Thomsen, Jane Froelund
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 22.10.2021; BMJ Publishing Group LTD
• Subjects: Accelerometers; Angular velocity; Confidence intervals; Dentistry; Employment; Epidemiology; Exposure; In vivo methods and tests; Intervertebral discs; Neck; Occupational exposure; Position measurement; Poster Presentations; Posture; Regression analysis; Regression models; Risk analysis; Risk factors; Risk reduction; Sensitivity analysis; Statistical analysis; Velocity
• ISSN: 1351-0711; 1470-7926
• DOI: 10.1136/OEM-2021-EPI.176

IntroductionSome observational and in vivo studies suggest dynamic neck movements and positions as causes of cervical disc disease. However, epidemiological evidence using objective measurements on neck position and movements as exposure is limited.ObjectivesWe studied the associations between objectively measured occupational neck movements and postures and CDH.MethodsWe formed a cohort of 852,625 Danish workers who ever held at least one of 29 jobs (e.g. dentists, hairdressers, childcare, carpenters) from 1981 to 2016. Representative whole work-day inclinometric measurements using triaxial accelerometers measuring neck angular velocity and posture of the neck were used as exposure. Job titles were retrieved from the Danish Occupational Cohort with eXposure data (DOC*X) database. First diagnosis of CDH was retrieved from the Danish National Patient Register. The risk of CDH by quintiles of cumulated exposure was assessed by incidence rate ratios (IRR), adjusted for age, sex, calendar -year, previous lumbar disc herniation and education, using Poisson regression models.ResultsWe found 14,000 cases of CDH during 20.2 million person-years of follow-up. Crude analyses showed an increasing IRR of CDH with increasing angular velocity of the neck. However, in the fully adjusted model increasing levels of neck angular velocity showed a decreasing risk with IRR 0.90 [95% confidence interval (CI) 0.86–0.95] when the highest quintile (dynamic work) was compared to the lowest (static work). Similar results were found for extension and flexion of the neck. Multiple sensitivity analyses did not change the results.ConclusionIn this large register-based study, we found no evidence of an increased risk of CDH in jobs with high velocity of movements or extreme positions of the neck. Other factors than dynamic neck movements and bent neck position seem to be important in the development of CDH.