Edinburgh Medical School, The University of Edinburgh, Edinburgh, UK.
Usher Institute, The University of Edinburgh, Edinburgh, UK.
J Glob Health. 2022 May 21;12:05014. doi: 10.7189/jogh.12.05014.
Long COVID is defined as symptoms and signs related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that are present at least four weeks following acute infection. These symptoms and signs are poorly characterised but may be associated with significant morbidity. We sought to synthesise the evidence on their incidence to guide future research, policy and practice.
We searched Medline and Embase for longitudinal cohort studies from January 2020 to July 2021 that investigated adults with long COVID at least four weeks after acute infection. Risk of bias was assessed using the Joanna Briggs Institute checklist for cohort studies. Random-effects meta-analyses were performed with subgroup analysis by follow-up time (4-12 vs more than 12 weeks).
19 studies were included, 13 of which included patients hospitalised with COVID-19. The total sample size was 10 643 and the follow-up time ranged from 30 to 340 days. Risk of bias was assessed as high in one study, moderate in two studies and low in the remaining 16 studies. The most common symptoms and signs seen at any time point in long COVID were fatigue (37%; 95% confidence interval (CI) = 23-55), dyspnoea (21%; 95% CI = 14-30), olfactory dysfunction (17%; 95% CI = 9-29), myalgia (12%; 95% CI = 5-25), cough (11%; 95% CI = 6-20) and gustatory dysfunction (10%; 95% CI = 7-17). High heterogeneity was seen for all meta-analyses and the presence of some funnel plot asymmetry may indicate reporting bias. No effect of follow-up time was found for any symptom or sign included in the subgroup analysis.
We have summarised evidence from longitudinal cohort studies on the most common symptoms and signs associated with long COVID. High heterogeneity seen in the meta-analysis means pooled incidence estimates should be interpreted with caution. This heterogeneity may be attributable to studies including patients from different health care settings and countries.
长新冠定义为急性感染后至少四周出现的与严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）相关的症状和体征。这些症状和体征特征描述较差，但可能与显著的发病率有关。我们试图综合这些证据，以指导未来的研究、政策和实践。
我们检索了 Medline 和 Embase 数据库，以获取 2020 年 1 月至 2021 年 7 月期间至少在急性感染后四周调查长新冠患者的纵向队列研究。使用 Joanna Briggs 研究所的队列研究清单评估偏倚风险。对随访时间（4-12 周与超过 12 周）进行亚组分析，然后进行随机效应荟萃分析。
纳入了 19 项研究，其中 13 项研究纳入了因 COVID-19 住院的患者。总样本量为 10643 例，随访时间从 30 天到 340 天不等。一项研究的偏倚风险评估为高，两项研究的偏倚风险评估为中，其余 16 项研究的偏倚风险评估为低。长新冠患者在任何时间点最常见的症状和体征是疲劳（37%；95%置信区间 [CI]：23-55）、呼吸困难（21%；95% CI：14-30）、嗅觉功能障碍（17%；95% CI：9-29）、肌痛（12%；95% CI：5-25）、咳嗽（11%；95% CI：6-20）和味觉功能障碍（10%；95% CI：7-17）。所有荟萃分析均显示出高度异质性，一些漏斗图的不对称性可能表明存在报告偏倚。在亚组分析中，任何症状或体征均未发现随访时间的影响。
我们总结了关于长新冠相关最常见症状和体征的纵向队列研究证据。荟萃分析中观察到的高度异质性意味着汇总的发病率估计值应谨慎解释。这种异质性可能归因于研究纳入了来自不同医疗保健环境和国家的患者。
