RESUMO
ObjectiveTo understand the frequency, profile, and duration of persistent symptoms of covid-19 and to update this understanding as new evidence emerges. DesignA living systematic review produced in response to the rapidly evolving evidence base for long covid. Data sourcesMedline and CINAHL (EBSCO), Global Health (Ovid), WHO Global Research Database on covid-19, LitCOVID, and Google Scholar to 28th September 2020. Study selectionStudies reporting long-term symptoms and complications among people with confirmed or suspected covid-19, both in those previously hospitalised and those never hospitalised. Only studies incorporating over 100 participants qualified for data extraction and were assessed for risk of bias. Results were analysed using descriptive statistics. Quality assessmentRisk of bias was assessed using a quality assessment checklist for prevalence studies. ResultsTwenty-eight studies qualified for data extraction; 16 of these were cohort studies, ten cross-sectional, and two large case series. The analysis included 9,442 adults with covid-19 from 13 countries. The longest mean follow-up period was 111 (SD: 11) days post-hospital discharge. A wide range of systemic, cardiopulmonary, gastrointestinal, neurological, and psychosocial symptoms was reported, of which the most common were breathlessness, fatigue, smell and taste disturbance, and anxiety. Persistent symptoms were described across both previously hospitalised and non-hospitalised populations. The quality of evidence was low, with a high risk of bias and heterogeneity in prevalence. The incorporated studies demonstrated limited external validity, a lack of control subjects, and inconsistent data collection methods. Few studies were conducted in primary care, no studies focused solely on children, and no studies were set in low- and middle-income countries. ConclusionOur findings suggest that long covid is a complex, heterogeneous condition; however, the limited evidence base currently precludes a precise definition of its symptoms and prevalence. There is a clear need for robust, controlled, prospective cohort studies, including different at-risk populations and settings, incorporating appropriate investigations, collected and recorded in a standardised way. Systematic review registrationThe protocol was prospectively registered on the PROSPERO database (CRD42020211131). Readers noteThis living systematic review will be updated regularly as new evidence emerges. The search terms and inclusion criteria will be updated in line with new evidence, research priorities and policy needs. This version is the original publication. Updates may occur for up to two years from the date of original publication. When citing this paper please consider adding the version number and date of access for clarity. O_TEXTBOXSection 1: What is already known on this topic? O_LIA significant number of people continue to describe symptoms long after the acute phase of covid-19 is over, so called long covid. C_LIO_LIThere is no case definition for long covid, which appears to be a heterogeneous condition with an uncertain prevalence. C_LI Section 2: What this study adds O_LIThis living systematic review provides a comprehensive summary of the published evidence on persistent symptoms of covid-19 and will be regularly updated. C_LIO_LIThe breadth of reported symptoms suggests a complex, heterogeneous condition affecting both hospitalised patients and those managed in the community. C_LIO_LIHowever, the current evidence base of the clinical spectrum of long covid is of limited quality and is vulnerable to biases. C_LIO_LIOur review identifies those areas where further long covid research is critically needed. C_LI C_TEXTBOX