Global, regional, and national burdens of shoulder dislocation in adolescents and young adults, 1990-2021: A population-based study

To the Editor: Traumatic and atraumatic shoulder instability is common in adolescents and young adults (AYAs), and this population is at high risk of recurrent instability following initial shoulder dislocation.[1] The prevalence rate of recurrent instability after first-time anterior traumatic shoulder dislocation has been reported to exceed 26%.[2] Shoulder dislocations commonly occur during traumatic events or high-contact sports, especially in athletes and military personnel. The consequences of shoulder instability extend beyond the initial injury, with significant short-term and long-term effects. Few studies have examined the epidemiology of shoulder instability in young athletic populations. Although some studies have reported the epidemiology of shoulder dislocations in specific populations, these findings are often fragmented and lack a comprehensive national or population-level perspective.[3,4] In this study, we investigated the temporal trends in the incidence, prevalence, and years lived with disability (YLDs) due to shoulder dislocation in individuals aged 15–39 years by social development level, age, and sex globally, regionally, and nationally from 1990 to 2021. Shoulder dislocation is defined as the complete displacement of the humeral head from the glenoid fossa of the scapula, typically caused by traumatic events. We collected and summarized crude estimates for incidence, prevalence, and YLDs of shoulder dislocation in individuals aged 15–39 years, along with their corresponding 95% uncertainty intervals (UIs). All values are reported per 100,000 people and sourced from the Global Burden of Disease (GBD) 2021 Study. Additionally, the sociodemographic index (SDI), which is a composite metric that reflects a country’s or region’s level of sociodemographic development and is derived from factors such as income per capita, education levels, and fertility rates,[5] was also introducd to assess the burden of shoulder dislocation in AYAs. The incidence, prevalence, and YLD rates of shoulder dislocation among individuals aged 15–39 years all showed a downwards trend from 1990 to 2021. Specifically, the incidence rate decreased from 107.32 (95% UI: 82.90 to 146.17) per 100,000 people in 1990 to 80.22 (95% UI: 61.02 to 109.61) per 100,000 people in 2021. Similarly, the prevalence rate decreased from 15.82 (95% UI: 3.40 to 28.59) per 100,000 people in 1990 to 11.83 (95% UI: 2.60 to 21.78) per 100,000 people in 2021. The YLD rate also slightly decreased from 0.98 (95% UI: 0.19 to 2.05) per 100,000 people in 1990 to 0.73 (95% UI: 0.14 to 1.53) per 100,000 people in 2021. To further investigate the temporal trend of shoulder dislocation in AYAs from 1990 to 2021, we conducted joinpoint regression analysis via the joinpoint regression program (version 5.1.0.0; National Cancer Institute, Bethesda, Maryland, USA). The results revealed a general declining trend across both sexes, with notable differences between males and females [Supplementary Figure 1, https://links.lww.com/CM9/C557]. In 2021, the incidence and prevalence of shoulder dislocation among individuals aged 15–39 years varied significantly across global [Supplementary Table 1, https://links.lww.com/CM9/C557]. In 2021, the burden of shoulder dislocation among individuals aged 15–39 years varied significantly across 21 GBD regions, with notable patterns in incidence, prevalence, and YLD rates. The incidence of shoulder dislocation was highest in Eastern Europe, followed by Australasia, Central Europe, Southern Latin America, and Western Europe. Conversely, the lowest incidence was observed in Western Sub-Saharan Africa, Central Sub-Saharan Africa, and Eastern Sub-Saharan Africa. Prevalence showed a similar regional pattern, with the highest rates in Eastern Europe and the lowest in Sub-Saharan African regions. YLD rates also followed this trend, with higher values in European and Australasian regions and lower values in Sub-Saharan Africa. Significant sex-based differences were also observed, with males exhibiting a notably greater disease burden than females [Supplementary Figure 2, https://links.lww.com/CM9/C557]. High- and high-middle-SDI regions consistently presented the highest incidence, prevalence, and YLD rates among AYAs, with a steady decline observed across all three measures over time. The average annual percent change (AAPC) with 95% confidence intervals (CIs) was calculated to identify significant trend shifts. In high-SDI regions, the AAPC for incidence in AYAs was –1.0326 (95% CI: –1.0899 to –0.9753; P <0.001), indicating a substantial reduction. Similarly, the AAPC for prevalence in AYAs was –1.0289 (95% CI: –1.0862 to –0.9714; P <0.001), and the AAPC for YLD rates was –1.0293 (95% CI: –1.0867 to –0.9719; P <0.001). The AAPC values for SDI regions are provided in Supplementary Table 2, https://links.lww.com/CM9/C557. In contrast, the middle, low-middle, and low-SDI regions also showed an overall downwards trend, albeit with fluctuations [Supplementary Figure 3, https://links.lww.com/CM9/C557]. Globally and across all five SDI regions, the incidence of shoulder dislocation in AYAs declined from 1990 to 2021. Among the age groups, the highest incidence was in individuals aged 20–24 years, with rates of 117.44 (95% UI: 86.47 to 162.50) per 100,000 people in 1990, which decreased to 87.90 (95% UI: 63.50 to 122.01) per 100,000 people in 2021 [Figure 1A]. Similarly, the prevalence of shoulder dislocation has shown a global decline. The highest prevalence rate among age groups was also in the 20–24 years group, decreasing from 17.29 (95% UI: 3.67 to 31.47) per 100,000 people in 1990 to 12.94 (95% UI: 2.78 to 23.89) per 100,000 people in 2021 [Figure 1B]. The highest YLD rate was observed among individuals aged 20–24 years, with rates decreasing from 1.07 (95% UI: 0.21 to 2.24) per 100,000 people in 1990 to 0.80 (95% UI: 0.16 to 1.73) per 100,000 people in 2021 [Figure 1C]. Additionally, we also observed that the burden of shoulder dislocations was greater in the 20–24 age group in high-SDI regions, whereas the burden was more pronounced in the 15–19 age group in low-SDI regions.Figure 1: Age distribution and temporal changes in incidence, prevalence, and YLD rates of shoulder dislocation among adolescents and young adults (ages 15-39) by SDI regions and age groups (1990-2021). (A) Incidence of shoulder dislocation globally and in five SDI regions from 1990 to 2021. (B) Prevalence of shoulder dislocation globally and in five SDI regions from 1990 to 2021. (C) YLD rates of shoulder dislocation globally and in the five SDI regions from 1990 to 2021. SDI: Sociodemographic index; YLD: Years lived with disability.Further analysis was conducted on the regional variations in the disease burden of shoulder dislocations among AYAs across America, Asia, Africa, and Europe from 1990 to 2021. The results are provided in Supplementary Figure 4, https://links.lww.com/CM9/C557. Compared with global trends, the burden of shoulder dislocations in the Chinese AYA population presents distinct characteristics, with a fluctuating pattern over time. In particular, males consistently had a significantly greater burden of shoulder joint dislocations than females do, with a notable upwards trend observed since 2009 [Supplementary Figure 5, https://links.lww.com/CM9/C557]. Several limitations must be acknowledged. First, the GBD 2021 study relies on model estimates, which inherently introduce uncertainty that may affect the reliability of our findings. Second, disparities in health information systems and reporting mechanisms across countries, particularly in underdeveloped or low-SDI regions, could lead to incomplete data and biases, impacting the accuracy of the results. Third, there is a time lag in the available data on disease burden, which may affect the timeliness of the findings. The global burden of shoulder dislocation in AYAs decreased from 1990 to 2021. However, it remains a significant public health issue, particularly among males aged 20–24 years in high-SDI regions. In contrast, in low-SDI regions, the burden is more pronounced in the 15–19 age group. Males present higher rates of incidence, prevalence, and YLD than females. Understanding these global epidemiological trends, especially in high-risk populations, is crucial for developing effective prevention and intervention strategies. Future research should prioritize addressing health disparities across different socioeconomic regions and investigating the influence of sociodemographic factors, such as age and sex, on the burden of shoulder dislocation. Funding This research was supported by the National Natural Science Foundation of China (82272569), as well as the 1.3.5 Project for Disciplines of Excellence at West China Hospital, Sichuan University. Conflicts of interest None.