[A dose-response meta-analysis on the relationship between daily tea intake and cardiovascular mortality based on the GRADE system].

Objective: To explore the relationship between daily tea intake and cardiovascular disease (CVD) mortality. Methods: PubMed, EMbase, The Cochrane, Chinese Biomedical Literature Database, CNKI, and Wanfang Database were searched to collect research on tea intake and CVD mortality. The search period was from the establishment of the database to June 2020. Two researchers independently screened and extracted literature. The risk of bias was evaluated in the included studies, a dose-response meta-analysis was conducted, sensitivity analysis and publication bias analysis of the research results, and quality evaluation of the included literature and GRADE classification of the evidence body were performed. Results: A total of 21 cohort or case-control studies were included, including 1 304 978 subjects. Among them, 38 222 deaths from CVD were reported. The quality scores of the included studies were all ≥ 6 points. The dose-response meta-analysis showed that for every additional cup of tea intake per day, the mortality rate of CVD decreased by about 3% (95%CI 0.95-0.98, P<0.05), and there was a non-linear dose-response relationship (P<0.05). Compared with people who do not drink tea, people who drink 1 to 8 cups of tea a day have 8% lower CVD mortality (RR=0.92, 95%CI 0.89-0.95), 13% (RR=0.87, 95 %CI 0.84-0.91), 15% (RR=0.85, 95%CI 0.82-0.89), 15% (RR=0.85, 95%CI 0.81-0.89), 16% (RR=0.84, 95%CI 0.80-0.89), 16% (RR=0.84, 95%CI 0.81-0.88), 16% (RR=0.84, 95%CI 0.81-0.87), 16% (RR=0.84, 95%CI 0.80-0.88), respectively. The results of traditional meta-analysis showed that compared with people who do not drink tea, people who drink more than 1 cup of tea a day are associated with 14% lower CVD mortality rate (RR=0.86, 95%CI 0.81-0.91, I2=73.2%, P<0.05). The results of subgroup analysis showed that compared with the corresponding people who did not drink tea, men who drank more than 1 cup of tea a day reduced the CVD mortality rate by 24%, women by 14%, European and American populations by 12%, and Asian populations by 15%. The population who consumed green tea decreased CVD mortality by 15%, and the population of non-smokers decreased CVD mortality by 20% (all P<0.05). The population who consumed black tea decreased CVD mortality by 8%, and the smoking population who consumed black tea decreased CVD mortality by 3%, and the difference was not statistically significant (all P>0.05). The results of the bias analysis showed that Begg=0.42 and Egger=0.62, indicating that the distribution on both sides of the funnel chart is symmetrical, suggesting that there is no publication bias. The results of sensitivity analysis showed that the effect size of the outcome index did not change significantly after excluding any article, indicating that the results are robust and credible. The GRADE evaluation showed that the evidence grades of the outcome indicators were all low grade. Conclusions: Daily tea consumption is related to reduced CVD mortality. It is therefore recommended to drink an appropriate amount of tea daily.目的： 探讨茶每日摄入量与心血管疾病（CVD）死亡率的关系。 方法： 检索PubMed、EMbase、The Cochrane、中国生物医学文献数据库、中国知网和万方数据库，搜集有关茶摄入量与CVD死亡率的相关研究，检索时限均从建库至2020年6月。由2名研究者独立筛选、提取文献。评价纳入研究的偏倚风险，进行剂量-反应荟萃分析，对研究结果进行敏感性分析和发表偏倚分析，并对结局指标进行证据体的GRADE分级。 结果： 共纳入21篇队列或病例对照研究，包括1 304 978名受试者，其中CVD死亡人数为38 222例，纳入研究质量评分均≥6分。剂量-反应荟萃分析结果显示，茶摄入量每天每增加1杯CVD死亡率下降约3%（95%CI 0.95~0.98，P<0.05），且存在一种非线性剂量反应关系（P<0.05）；与不喝茶的人群相比较，每天喝1~8杯茶的人群的CVD死亡率分别降低8%（RR=0.92，95%CI 0.89~0.95），13%（RR=0.87，95%CI 0.84~0.91），15%（RR=0.85，95%CI 0.82~0.89），15%（RR=0.85，95%CI 0.81~0.89），16%（RR=0.84，95%CI 0.80~0.89），16%（RR=0.84，95%CI 0.81~0.88），16%（RR=0.84，95%CI 0.81~0.87），16%（RR=0.84，95%CI 0.80~0.88）。传统荟萃分析结果显示，与不喝茶的人群相比，每天喝茶大于1杯的人群CVD死亡率可以降低14%（RR=0.86，95%CI 0.81~0.91，I2=73.2%，P<0.05）。亚组分析结果显示，与相对应的不喝茶的人群相比，每天喝茶大于1杯的男性CVD死亡率降低24%，女性降低14%，欧美人群降低12%，亚洲人群降低15%，饮用绿茶的人群降低15%，不吸烟人群降低20%，差异均具有统计学意义（P均<0.05）；饮用红茶的人群降低8%，吸烟人群降低3%，差异无统计学意义（P均>0.05）。偏倚分析结果显示Begg=0.42，Egger=0.62，表明漏斗图两侧分布对称，提示不存在发表偏倚。敏感性分析结果显示排除任何一篇文献结局指标效应量未发生明显变化，表明结果稳健可信。GRADE评价显示结局指标的证据分级均为低等级别。 结论： 每日饮用茶水能够降低CVD死亡率，推荐每天饮用适量茶水。.