RESUMO
BackgroundThe clinical sequelae (Long Covid) of acute Covid-19 are recognised globally, yet the risk of developing them is unknown. MethodsA living systematic review (second version). Bibliographical records from the C19 Living Map Long Covid segment (22nd February 2022), Medline, CINAHL, Global Health, WHO Covid-19 database, LitCOVID, and Google Scholar (18th November 2021). We included studies with at least 100 people at 12 weeks or more post-Covid-19 onset and with a control group without confirmed Covid-19. Risk of bias was assessed using the Newcastle-Ottawa scale. Symptoms are aligned with the Post Covid-19 Condition Core Outcome Set. We present descriptive statistics and use meta-analysis to estimate the relative risk of experiencing Long Covid. ResultsTwenty-eight studies were included: 20 cohort, five case-controls, three cross-sectional. Studies reported on 242,715 people with Covid-19 (55.6% female) and 276,317 controls (55.7% female) in 16 countries. Most were of moderate quality (71%). Only two were set in low-middle-income countries and few included children (18%). The longest mean follow-up time was 419.8 (standard deviation 49.4) days post-diagnosis. The relative risk (RR) of experiencing persistent or new symptoms in cases compared with controls was 1.53 (95% CI: 1.50 to 1.56). The core outcomes with the highest increased risk were cardiovascular (RR 2.53 95% CI: 2.16 to 2.96), cognitive (RR 1.99; 95% CI: 1.82 to 2.17), and physical functioning (RR 1.85; 95% CI: 1.75 to 1.96). ConclusionSARS-CoV-2 infection is associated with a higher risk of new or persistent symptoms when compared with controls that can last over a year following acute Covid-19. There is still a lack of robust studies set in lower resourced settings and current studies have high heterogeneity and potential misclassifications of cases and controls. Future research should explore the role of vaccination and different variants on the risk of developing Long Covid. Systematic review registrationThe protocol was prospectively registered on the PROSPERO database (CRD42020211131). O_TEXTBOXO_TEXTBOXNOSection 1:C_TEXTBOXNO What is already known?O_LIPublished evidence indicates a high prevalence of people affected by post-acute SARS-CoV-2 sequelae often referred to as Long Covid; yet these estimates are impacted by heterogeneity in study design and a lack of controlled studies and core outcome sets. C_LIO_LIOur first version of this review, looking at studies till March 2021, identified a breadth of reported symptoms of Long Covid affecting both those who were hospitalised during the acute phase and those managed in the community. We also identified a lack of studies including children and set in low-middle income countries. C_LIO_LIThe most commonly reported symptoms identified were weakness, general malaise, fatigue, concentration difficulties, and breathlessness, suggesting Long Covid is a complex, heterogeneous condition. C_LI O_TEXTBOXNOSection 2:C_TEXTBOXNO What are the new findings?O_LITo address the limitations identified, this first update of our living systematic review provides a comprehensive summary of peer-reviewed published studies with a control group (till 22nd February 2022) on the risk of experiencing Covid-19 sequelae. C_LIO_LIDespite study limitations identifying control groups, our findings suggest that people with a confirmed previous SARS-CoV-2 infection are 1.5 times more likely to experience new or persisting symptoms at 12 or more weeks post-onset when compared to a control group. C_LIO_LIMapped to the new Core Outcome set for Post-Covid-19 Condition, a framework for standardised assessment, our review identifies cardiovascular functioning, cognitive functioning, and physical functioning as the outcomes with highest increased risk for people post-SARS-CoV-2 infection compared to controls. C_LI O_TEXTBOXNOSection 3:C_TEXTBOXNO What do the new findings imply?O_LIOur findings point to a clear association between exposure to SARS-CoV-2 and the risk of developing new or persistent symptoms, for some lasting longer than 12 months after the initial infection. C_LIO_LIControlled studies on Long Covid should focus on improving quality to enable multisite metaanalysis by using standardised research protocols and by evaluating participants with multiple standardised diagnostic tests at various time points to capture transitory and intermittent symptoms and complications. C_LIO_LITo help inform health system planning and rehabilitation to improve outcomes for those affected, Long Covid research should focus on estimating the burden of post-acute SARS-CoV-2 in lower resourced settings, investigating the impact of vaccination and variants on Long Covid, and investigating therapeutic strategies. C_LI C_TEXTBOX
