Table 1.

Characteristics of included studies in the review

N°	Author(s) and year	Country	Main aim of the study	Study population	Study design	Sample size (% female)	Age (mean or median)
1	Subramanian et al., 2022 [35]	United Kingdom	To investigate a comprehensive range of symptoms previously reported to be associated with long COVID by epidemiological studies, patients and clinicians. To assess their association with confirmed SARS-CoV-2 infection at least 12 weeks after infection in non-hospitalized adults, compared to a propensity score-matched cohort of patients with no recorded evidence of SARS-CoV-2 infection. To assess associations between demographic and clinical risk factors, including comorbidities, with the development of long COVID and characterized dominant symptom clusters	Adults with confirmed SARS-CoV-2 with symptoms persisting beyond 12 weeks, from a UK-based primary care database, propensity score-matched adults with no recorded evidence of SARS-CoV-2 infection	Retrospective cohort study	N = 2 430 729 (55.3%) Sample size for analysis of risk factors for long covid: N = 384 137 (55.3%)	43.8 ± 16.9 (mean)
2	Wang and al., 2022 [36]	USA	To determine whether high levels of psychological distress before SARS-CoV-2 infection, characterized by depression, anxiety, worry, perceived stress, and loneliness, are prospectively associated with increased risk of developing post-COVID-19 conditions	Participants of 3 ongoing longitudinal studies (Nurses’ Health Study II (NHSII), Nurses’ Health Study 3(NHS3), and the Growing Up Today Study (GUTS)) with an antecedant of positive SARS-CoV-2	Prospective cohort study	N = 3 193 (96.4%)	Cases (post-Covid pain): 43 (σ 15.85) Controls (absence of pain): 45.71 (σ 13.89) (mean)
3	Grisanti and al., 2022 [37]	Italy	To characterize a population of patients with prior COVID-19 infection who showed signs and symptoms consistent with neurological long-COVID. Further, to analyze the patterns of symptoms persisting three months after the end of the acute phase of COVID-19 infection and discuss the presence of subtypes of neurological long- COVID, and their potential risk factors	Long Covid subjects with neurological symptoms	Prospective cohort study	N = 109 (50%)	55.17 (18-80) (mean)
4	Garjani and al., 2022 [38]	United Kingdom	To understand the course of recovery from coronavirus disease 2019 (COVID-19) among patients with multiple sclerosis (MS) and to determine its predictors, including patients’pre–COVID-19 physical and mental health status	Patients with multiple sclerosis who reported Covid-19 infection	Prospective cohort study	N = 571 (77.2%)	Not calculated in the overall study population
5	Craparo and al., 2022 [39]	Italy	To identify clusters of long COVID-19 symptoms using latent class analysis and investigate the psychological factors involved in the onset of this syndrome	Italian individuals with an official diagnosis of COVID-19 who recovered from the disease	Cross-sectional	N = 506 (86%)	Not calculated in the overall study population
6	Tene and al., 2022 [40]	Israel	To examine the prevalence of long COVID in a large population-based cohort and to characterize its demographics and clinical risk factors	Subjects who had a covid infection objectified by a RT-PCR test among membersof a large health provider in Israel	Historical cohort	N = 180 759 (49.6%)	32.9 (σ 19) (mean)
7	De Oliveira and al., 2022 [41]	Brazil	To describe the prevalence and type of consequences of COVID-19 after acute recovery,evaluate the quality of life, and identify potential risk factors associated with long COVID	Surviving patients with Covid-19 discharged from Eduardo de Menezes Hospital	Cross sectionnal	N = 439 (49.7%)	58 (47-67) (median)
8	Ohira and al., 2022 [42]	Japan	To examine the clinical characteristics of patients with long COVID in Japan	Long Covid subjects visiting a clinic (Department of General Internal Medicine of the National Center of Neurology and Psychiatry) in Japan	Cross sectional	N = 91 (56.7%)	39.8 (σ 14.7) (mean)
9	Bai and al., 2022 [43]	Italy	To investigate the incidence of physical and/or psychological symptoms characterising the"long COVID"syndrome in female gender and to study the possible predictors of long COVID	Adults hospitalized for a SARS-CoV-2 infection who were evaluated at the post-COVID outpatient clinic	Prospective cohort	N = 377 (36.3%)	57 (49–68) (median)
10	Daitch and al., 2022 [44]	Israel, Switzerland, Spain, and Italy	To describe the prevalence of long-COVID symptoms among older adults and to explore independent risk factors for two of the most common long-COVID symptoms: fatigue and dyspnea	Adults with a polymerase chain reaction-proved COVID-19 diagnosis at least 30 days before the clinic visit	Cross sectional	N = 2 333 (49.2%)	51.25 (σ 16.39) (mean)
11	Afroze and al., 2022 [45]	Bangladesh	To assess the prevalence, incidence rate, evolution over time, and risk factors of post-covid-19 syndrome (PCS) among hospitalized (HS) and non-hospitalized (NHS) COVID-19 survivors	Adults with RT-PCR-confirmed COVID-19 and sought care from the study hospitals with or without the requirement for hospitalization, and showed significant improvement of symptoms for three consecutive days with concomitante hospital discharge	Prospective cohort study	N = 362 (38%)	50 (38–60) (median)
12	Vásconez-González and al., 2023 [46]	Ecuador	To describe persisting symptoms after COVID-19 infection in pregnant and non-pregnant women in Ecuador	Pregnant and non-pregnant women in Ecuador with an history of Covid-19 infection	Cross sectional	N = 457 (100%)	Not calculated
13	Frontera and al., 2022 [47]	USA	To evaluate the impact of four categories of predictors on 6- and 12-month outcome metrics including: demographics, pre-COVID-19 comorbidities, index COVID-19 hospitalization metrics, and life stressors within the month prior to interview	Patients hospitalized with acute Covid infection 6 and 12 months before follow-up interview	Prospective cohort	At 6 months follow up: N = 382 (35%) At 12 months follow up: N = 242 (36%)	At 6 months follow up: 69 (57–78) At 12 months follow up: 65 (53–73) (median)
14	Shukla and al., 2023 [48]	India	To assess the nature and prevalence of medical sequelae following COVID-19 infection, and risk factors, if any	Health care workers between 12 and 52 weeks post discharge after COVID-19 infection	Cross sectional	N = 679 (50.81%)	31.49 ± 9.54 (mean)
15	Jacobs and al., 2023 [49]	USA	To ascertain which pre-existing conditions engendered a greater risk for the development of post-acute sequelae of covid (PASC) after SARS-CoV-2 infection	Arizona residents with an history of acute Covid infection	Prospective cohort	N = 1 224 (45.6% in PACS + and 54.4% in PACS -)	PACS -: 47 (33–60) PACS + : 49 (36–60) (median)
16	Knight and al., 2022 [50]	USA	To assess, characterize, and describe the prevalence and predicting factors of patient-reported severe coronavirus disease 2019 (COVID-19) infection and post-acute sequelae of COVID-19 (PASC)	Adults with an history of acute Covid infection who received care in the COVID-19 virtual clinic	Cross sectional	N = 437 (60.2%)	54 (18 − 99) (median)
17	Sansone and al., 2022 [51]	Italy	To investigate the persistence of symptoms 15 months since COVID-19 diagnosis in patients referring to the post-COVID-19 clinic in Trieste (north-eastern Italy)	Long covid subjects attending the Long-COVID-19 outpatient clinic of Trieste	Prospective cohort	N = 247 (64.4%)	48.1 (σ 10.5) (mean)
18	Yavuz and al., 2022 [52]	Turkey	To reveal post-COVID-19 neurological symptoms and risk factors for their development	Adults applied to four local Neurology Outpatient Clinics (two centers at city of Ankara, one each center at the city of Yozgat and Tokat) at least four weeks after contracting COVID-19 infection (confirmed by a laboratory test)	Cross sectional	N = 400 (61%)	39.9 (σ 13.7) (mean)
19	Gutiérrez-Canales and al., 2022 [53]	Mexico	To identify sequelae and persistent symptoms, as well as their influence on quality of life, in outpatients who had recovered from COVID-19	Adults unvaccinated against SARS-CoV-2 at the time of infection, who had recovered from COVID-19 (2 to 12 months after the onset of symptoms)	Prospective cohort	N = 206 (62.6%)	28 (22–45.5) (median)
20	Hastie and al., 2022 [54]	Scotland	To determine the frequency, nature, determinants and impact of long-COVID in the general population	Adults in Scotland with a positive PCR test for SARS-CoV-2 with a comparison group who had had a negative test but never had a positive test	Prospective cohort	N = 96 238 (39%)	45 (median)
21	Fleischer and al., 2022 [55]	Germany	To validate subjective neurological complaints in patients with post-COVID-19 by applying a comprehensive neuropsychiatric diagnostic workup	Subjects fulfilling the WHO Delphi consensus criteria for post-COVID-19 syndrome	Prospective cohort	N = 171 (66.7%)	45.2 ± 12.7 (mean)
22	Margalit and al., 2022 [56]	Israel	To assess risk factors for long-COVID fatigue and explored its possible pathophysiology	Adults who recovered from COVID-19 (had to be at least 2 months following a PCR–proven diagnosis of COVID-19)	Case–Control	N = 141 (59%)	47 (σ 13) (mean)
23	Gasnier and al., 2022 [57]	France	To investigate the association between long COVID, psychiatric symptoms and psychiatric disorders	Subjects admitted in intensive care unit during acute phase of Covid-19 and/or reporting long COVID complaints	Cross sectional	N = 177 (unspecified)	Not calculated in the overall study population
24	Loosen and al., 2022 [58]	Germany	To study the prevalence of Long COVID Syndrome (LCS) in Germany and to identify clinical factors associated with its development	Patients with a confirmed diagnosis of COVID-19 (ICD-10: U07.1) from one of 1056 GP practices that routinely send data to the Disease Analyzer database	Cross sectional	N = 50 402 (54.5%)	48.8 (σ 19.3) (mean)
25	Buonsenso and al., 2022 [59]	Italy	To evaluate the sequelae of COVID-19 in a population of workers who tested positive for COVID-19, with a follow-up within one year of the acute illness, and to analyse the possible association between COVID-19 sequelae and changes inthe workers occupational status	Adult members of the households of children diagnosed with SARS-CoV-2 infection (using RT-PCR) at the Department of Women and Child Health of the Fondazione Policlinico Universitario A. Gemelli IRCCS of Rome	Retrospective cohort	N = 155 (50.3%)	46.48 (σ 7.302) (mean)
26	Lhuillier and al., 2022 [60]	USA	To examine physical and psychiatric antecedents associated with COVID-19 illness severity and post-acute COVID-19 sequelae presence among individuals who endorsed any COVID-19 infection	People who participated in the rescue and recovery efforts on 9/11 for the World Trade Center with a a positive test result for COVID-19	Prospective cohort	N = 1280 (8.6%)	56.9 (σ 7.37) (mean)
27	Tleyjeh and al., 2022 [61]	Saudi Arabia	To determine the prevalence of COVID-19 associated symptoms 4 weeks or more after the onset of the disease and identify predictors associated with delayed return to baseline health state among these patients	Adults confirmed to have COVID-19 at least 4 weeks prior to the start of the survey	Cross sectional	N = 5946 (35.6%)	Not calculated
28	Kidwai and al., 2022 [62]	Pakistan	To determine the prevalence of post–COVID syndrome in a cohort of faculty working in Fazaia Ruth Pfau Medical College (FRPMC), Karachi, Pakistan, and their family members	Faculty members of Fazaia Ruth Pfau Medical College (FRPMC) and their family, who suffered from COVID infection and who tested positive by polymerase chain reaction (PCR) test	Cross sectional	N = 84 (48.81%)	47.15 ± 14.81 (mean)
29	Magdy and al., 2021 [63]	Egypt	To assess risk factors for persistent neuropathic pain in subjects recovered from coronavirus disease 2019 (COVID-19) and to study the serum level of neurofilament light chain (NFL) in those patients	Subjects with post-COVID-19 pain and age and sex-matched healthcare workers who recovered from COVID-19 without pain	Case–control	N = 90 (65.5%)	Cases (post-Covid pain): 43 (σ 15.85) Controls (absence of pain): 45.71 (σ 13.89) (mean)
30	Abdelhafiz and al., 2022 [64]	Egypt	To evaluate the prevalence of post-COVID-19 symptoms among Egyptian patients and detecting the factors associated with the presence of these symptoms	Egyptian subjects who had history of COVID-19 disease	Cross sectional	N = 396 (78.54%)	41.402 ± 11.151 (mean)
31	Ghoshal and al., 2021 [65]	India and Bangladesh	To study the frequency and spectrum of post-infection-FGIDs among COVID-19 and historical healthy controls and the risk factors for its development	Adults with an history of acute Covid infection, compared with a cohort of healthy subjects published earlier	Case–control	N = 280 (72.9%)	39.5 ± 15.4 (median)
32	Peter and al., 2022 [66]	Germany	To describe symptoms and symptom clusters of post-covid syndrome six to 12 months after acute infection, describe risk factors, and examine the association of symptom clusters with general health and working capacity	Adults aged 18–65 years with confirmed SARS-CoV-2 infection between October 2020 and March 2021 notified to health authorities in four geographically defined regions in southern Germany	Cross sectional	N = 11 710 (58.8%)	44.1 (σ 13.7) (mean)
33	Alkwai and al., 2022 [67]	Saudi Arabia	To describe and characterise the prevalence of persistent COVID-19 symptoms beyond three months and to evaluate the risk factors for the delayed return to the usual state of health	Adults with a COVID-19 diagnosis 3 months prior to the study	Cross sectional	N = 213 (76.1%)	Not calculated; 90.1% under 45 years of age
34	Colizzi and al., 2022 [68]	Italy	(i) to analyze the course of mental health symptoms in COVID-19 survivors during the 12 months following the acute phase of the disease; and (ii) to identify sociodemographic and clinical predictors of post-COVID-19 mental health symptoms	Adults admitted or seen on an outpatient basis at the hospital Infectious Disease Department, with a confirmed diagnosis of COVID-19	Prospective cohort	N = 479 (52.6%)	54 (σ = 43–65) (median)
35	Martinez and al., 2021 [69]	Switzerland	To assess the frequency of persisting symptoms after COVID-19 infection in healthcare workers at a university hospital in Switzerland	Healthcare workers infected with SARS-CoV-2	Retrospective cohort	N = 260 (75.4%)	Age group: 30–39
36	Uygur and al., 2021 [70]	Turkey	To obtain an initial prevalence estimate of post-COVID-19 fatigue in Turkey and identify psychological and sociodemographic risk factors associated with post-COVID-19 fatigue	People in Turkey who had recovered from COVID-19 (from a community-based survey)	Cross sectional	N = 275 (58.2%)	34.67 ± 8.35 (mean)