Supplementary Material for: Prevalence of Cognitive Impairment and Dementia in Older Adults Living at High Altitude: A Systematic Review and Meta-Analysis

Introduction: Dementia is a chronic disease with a variable prevalence throughout the world; however, this could be higher at high-altitude populations. We aimed to summarize the prevalence of cognitive impairment and dementia in older adults living at high altitude. Methods: We searched in PubMed, Medline, Scopus, Web of Science, and Embase and included the studies published from inception to July 20, 2020, with no language restriction, which reported the frequency of cognitive impairment or dementia in older adults living at high-altitude populations. Random-effects meta-analyses were performed to calculate the overall prevalence and 95% confidence intervals (95% CI) of cognitive impairment and dementia. The risk of bias was evaluated using the Newcastle-Ottawa Scale (NOS) adapted for cross-sectional studies. Results: Six studies were included (3,724 participants), and 5 of the 6 included studies were carried out in Latin America. The altitude ranged from 1,783 to 3,847 m, the proportion of women included varied from 38.7 to 65.6%, and the proportion of participants with elementary or illiterate educational level ranged from 71.7 to 97.6%. The overall prevalence of cognitive impairment was 22.0% (95% CI: 8–40, I2: 99%), and the overall prevalence of dementia was 11.0% (95% CI: 6–17, I2: 92%). In a subgroup analysis according to the instrument used to evaluate cognitive impairment, the prevalence of cognitive impairment was 21.0% (95% CI: 5–42, I2: 99%) in the MMSE group while the prevalence was 29.0% (95% CI: 0–78) in the non-MMSE group. Conclusions: The prevalence of cognitive impairment and dementia in older adults living at high altitude is almost twice the number reported in some world regions.

引言：痴呆是一种慢性疾病，其全球患病率存在地域差异，但高海拔人群的患病率可能更高。本研究旨在总结居住在高海拔地区的老年人的认知障碍与痴呆患病率。方法：我们在PubMed、Medline、Scopus、Web of Science及Embase数据库中进行检索，纳入自数据库建库至2020年7月20日发表、无语言限制且报道高海拔地区老年人认知障碍或痴呆患病率的相关研究。采用随机效应荟萃分析计算认知障碍与痴呆的总体患病率及95%置信区间（95% CI）。采用适配横断面研究设计的纽卡斯尔-渥太华量表（Newcastle-Ottawa Scale, NOS）评估研究的偏倚风险。结果：本研究共纳入6项研究，涉及3724名参与者，其中5项研究在拉丁美洲开展。纳入研究的海拔范围为1783米至3847米，研究纳入的女性占比为38.7%至65.6%，具有初等教育或文盲教育水平的参与者占比为71.7%至97.6%。认知障碍的总体患病率为22.0%（95% CI：8~40，I²=99%），痴呆的总体患病率为11.0%（95% CI：6~17，I²=92%）。根据认知障碍评估工具进行亚组分析显示，使用简易精神状态检查表（MMSE）的亚组认知障碍患病率为21.0%（95% CI：5~42，I²=99%），非MMSE亚组的患病率为29.0%（95% CI：0~78）。结论：本研究结果表明，居住在高海拔地区的老年人的认知障碍与痴呆患病率几乎是全球部分地区报告数值的两倍。