Can we distinguish the roles of demographic and temporal changes in the incidence and prevalence of musculoskeletal disorders? A systematic search and review

Background Musculoskeletal disorders (MSDs) represent a major public health issue, affecting more than 40 million European workers in 2017. The overall ageing of the working population is expected to increase the burden of disease, but temporal changes in exposures or diagnosis may also drive global trends in MSDs. We, therefore, sought to review and summarize evidence describing the role of demographic and temporal changes in the occurrence of MSDs. Methods We conducted a systematic search and review of articles reporting temporal trends in MSDs in the general working-age population. Only articles controlling for age in the analysis were included. The risk of bias was assessed. The main indicators extracted were age-controlled time trends in MSD incidence or prevalence. Results Among 2,680 articles, 16 fulfilled the inclusion criteria, representing 23 results according to the indicators extracted. No study was found with a high risk of bias. Twelve results reported time trends in prevalence and 11 in incidence. After controlling for age, the reported temporal trends varied, mostly between non-monotonic changes (n=12/23) and increases (n=10/23); one article also highlighted an increase among women and non-monotonic changes among men (n = 1/23). Several factors other than ageing were suggested to explain temporal trends in MSDs, main trends in obesity, changing occupational exposures, and cultural factors regarding pain tolerance. Conclusion This review shows that different kinds of factors in addition to ageing may contribute to varying or increasing trends in MSDs. This review also highlighted the scarcity of evidence regarding time trends in the burden of MSDs and their underlying causes. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial not a clinical trials - its a systematic review ### Funding Statement All authors are salaried staff members of their respective institutions. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Not relevant since it is a review of the literature I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes In this literature review we use electronic bibliographic databases for studies published between 1990 and 2020: Medline, ScienceDirect, Wiley, and Web of Science