Supplementary Material for: The epidemiological trends and prediction of brain and central nervous system cancer incidence and mortality, 1992-2021: Age-period-cohort analysis

Introduction The study uniquely focuses on the global incidence, mortality, and temporal trends of brain and central nervous system (CNS) cancer from 1992 to 2021. It explores the association between the disease burden and factors such as age, period, and birth cohorts, and provides forecasts for future incidence and mortality.
Methods Leveraging the Global Burden of Disease 2021 data from 1992 to 2021, we calculated incidence, and deaths and their age-standardized rates (ASR) and assessed temporal trends using the average annual percent change derived from joinpoint regression analysis. To explore the impacts of age, period, and birth cohort in greater depth, we applied an age-period-cohort model. Additionally, a Nordpred age-period-cohort analysis was conducted to forecast the global epidemiological trends from 2022 to 2031.
Results The global incidence of brain and CNS cancer has increased from 2,831,075 in 1992 to 3,420,786 in 2021, and the number of mortalities has risen by 80.62%. The incidence ASR was highest in high sociodemographic index (SDI) regions, and showed an increasing trend. Conversely, the mortality ASR displayed downward trends in high-middle and high SDI regions. Notably, the age-period-cohort model suggests a recent increase in incidence risk, and a decline in mortality. From 2022 to 2031, the global mortality ASR was predicted to decrease whereas the incidence ASR increases slowly.
Conclusion The global trends in brain and CNS cancer incidence and mortality generally showed an increasing trend with considerable heterogeneity. Furtherly, high SDI regions where health care systems could conduct earlier and better medical interventions with better outcome for brain and CNS cancer.

引言
本研究独具特色地聚焦于1992年至2021年全球脑与中枢神经系统（central nervous system, CNS）肿瘤的发病、死亡及时间变化趋势，探讨疾病负担与年龄、时期、出生队列等因素的关联，并对未来的发病与死亡情况进行预测。

方法
本研究利用1992年至2021年的全球疾病负担2021（Global Burden of Disease 2021）数据，计算了发病数、死亡数及其年龄标化率（age-standardized rates, ASR），并通过连接点回归分析（joinpoint regression analysis）得到的年度平均变化百分比，评估其时间变化趋势。为深入探究年龄、时期及出生队列的影响机制，本研究采用了年龄-时期-队列模型（age-period-cohort model）。此外，本研究还开展了Nordpred年龄-时期-队列分析，以预测2022年至2031年的全球流行病学趋势。

结果
1992年至2021年，全球脑与CNS肿瘤的发病数从2831075例增长至3420786例，死亡人数上升了80.62%。高社会人口学指数（sociodemographic index, SDI）地区的发病年龄标化率最高，且呈持续上升趋势；与之相反，中高SDI与高SDI地区的死亡年龄标化率则呈现下降态势。值得注意的是，年龄-时期-队列模型提示近期发病风险有所升高，而死亡风险呈下降趋势。预计2022年至2031年，全球死亡年龄标化率将有所降低，而发病年龄标化率将缓慢上升。

结论
全球脑与CNS肿瘤的发病与死亡趋势总体呈上升态势，且存在显著的异质性。此外，高SDI地区的医疗系统可对脑与CNS肿瘤实施更早、更优质的医疗干预，从而获得更佳的诊疗结局。