Disentangling the roles of demographic and temporal changes in the incidence and prevalence of musculoskeletal disorders: a systematic review.

Background: Musculoskeletal disorders (MSDs) accounted for nearly 1.71 billion people worldwide in 2019 with an estimate of over 126.6 million Americans (or one in two adults) affected and 40 million European workers in 2017. Since age constitutes an important risk factor for MSDs, the overall aging of the working population is expected to influence the burden of disease. However, factors other than aging may play a role in the global trends in MSDs We conducted a systematic review to summarize the evidence on the role of demographic and temporal changes in the occurrence of MSDs. Methods: The study protocol was registered in PROSPERO with the number CRD42020221499. Following the PRISMA guidelines, we searched PubMed, ScienceDirect and Web of Science over the 1990-2020 period for articles reporting temporal trends in MSDs incidence or prevalence in the general working-age population. We only included articles controlling for age in the analysis. To ensure the quality of the articles, the bias risk was assessed using the RoB-SPEO tool. The main indicators we extracted were age-controlled time trends in MSDs incidence or prevalence. Results: Among 966 articles, 16 fulfilled the inclusion criteria, representing 23 results according to the indicators extracted. No study was found with a high risk of bias. Nine used a definition of MSDs based on pain and 14 based on repercussions on work or social life. Twelve results presented time trends in prevalence and 11 in incidence. After controlling for age, temporal trends in MSDs presented some heterogeneity. Indeed, 10 results documented increases and 12 reported non-monotonic changes. Only 1 result reported a decreasing trend in the incidence of MSDs. Several factors other than aging were suggested to explain temporal trends in MSDs, mainly trends in obesity, changing occupational exposures, and cultural factors regarding pain tolerance. Conclusion: This review shows that factors in addition to aging of the working population may contribute to varying or increasing trends in MSDs. Results also highlight the scarcity of available evidence on time trends in the burden of MSDs and their underlying causes.