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. 2024 May 10;19(5):e0298409. doi: 10.1371/journal.pone.0298409

Determinants of post-acute COVID-19 syndrome among hospitalized severe COVID-19 patients: A 2-year follow-up study

Tamrat Petros Elias 1,*, Tsegaye Wesenseged Gebreamlak 2, Tigist Tesfaye Gebremeskel 3, Binyam Lukas Adde 4, Abraham Sisay Abie 1, Bitaniya Petros Elias 5, Abel Mureja Argaw 1, Addis Aschenek Tenaw 6, Biruk Mulugeta Belay 1
Editor: Robert Jeenchen Chen7
PMCID: PMC11086844  PMID: 38728331

Abstract

Background

Post-acute COVID-19 syndrome is a condition where individuals experience persistent symptoms after the acute phase of the COVID-19 infection has resolved, which lowers their quality of life and ability to return to work. This study assessed the prevalence and associated risk factors of post-acute COVID-19 syndrome (PACS) among severe COVID-19 patients who were discharged from Millennium COVID-19 Care Center, Addis Ababa, Ethiopia.

Methods

A cross-sectional study using data collected from patient charts and a follow-up telephone interview after two years of discharge. Systematic random sampling was used to select a total of 400 patients. A structured questionnaire developed from the case report form for PACS of the World Health Organization (WHO) was used. Frequency and cross-tabulation were used for descriptive statistics. Predictor variables with a p-value <0.25 in bivariate analyses were included in the logistic regression.

Result

Out of the 400 patients, 20 patients were dead, 14 patients refused to give consent, and 26 patients couldn’t be reached because their phones weren’t working. Finally, 340 were included in the study. The majority (68.5%) were males and the mean age was 53.9 (±13.3 SD) years. More than a third (38.1%) of the patients reported the persistence of at least one symptom after hospital discharge. The most common symptoms were fatigue (27.5%) and Cough (15.3%). Older age (AOR 1.04, 95% CI 1.02–1.07), female sex (AOR 1.82, 95% CI 1.00–3.29), presence of comorbidity (AOR 2.38, 95% CI 1.35–4.19), alcohol use (AOR 3.05, 95% CI 1.49–6.26), fatigue at presentation (AOR 2.18, 95% CI 1.21–3.95), and longer hospital stay (AOR 1.06, 95% CI 1.02–1.10) were found to increase the odds of developing post-acute COVID-19 syndrome. Higher hemoglobin level was found to decrease the risk of subsequent post-acute COVID-19 syndrome (AOR 0.84, 95% CI 0.71–0.99).

Conclusion

The prevalence of post-acute COVID-19 syndrome is high, with a wide range of persistent symptoms experienced by patients. COVID-19 survivors with the identified risk factors are more susceptible to post-acute COVID-19 and require targeted monitoring and care in a multidisciplinary approach.

Introduction

SARS-CoV-2, which causes coronavirus disease-19 (COVID-19), emerged as a public health threat in December 2019 [1]. According to the online World Health Organization (WHO) COVID-19 dashboard, as of May 1, 2023, the COVID-19 pandemic affected more than 765 million people and caused more than 6.9 million deaths globally [2]. The detection and treatment of acute illness does not appear to be the end of the COVID-19 fight. It has lately come to light that some patients’ incapacitating symptoms might last for weeks or even months [3]. This manifestation was termed ‘post-acute COVID-19 syndrome’, ‘post COVID conditions’, ‘chronic COVID-19’, or ‘long COVID’ [4]. The number of post-acute COVID-19 patients is rapidly increasing because millions of people have already contracted the disease and many more will do so in the future [5]. The capacity of people to return to work can be seriously impacted by persistent COVID-19 symptoms, with substantial psychological, social, and economic repercussions for those affected, their families, and society as a whole [6]. The annual economic impact of PACS (exclusive of costs of disability services, social services, and lost income on the part of caretakers) in the United States ranges from $140 billion to $600 billion [7].

The pathophysiology of PACS is multi-factorial and more than one mechanism may be implicated in several clinical manifestations. Immune dysregulation, persistent inflammatory reactions, autoimmune mimicry, pathogen reactivation, and host-microbiome changes may all play a role in the development of the syndrome [8]. Its pathophysiology is significantly influenced by prolonged inflammation, which can also be the cause of other symptoms such as cognitive impairment and neurological problems. Similar to multisystem inflammatory syndrome in children (MIS-C), a multisystem inflammatory syndrome in adults (MIS-A) of all ages has also been recently described [9].

The prevalence and clinical presentation of PACS is highly heterogeneous. The most frequently reported symptoms are fatigue, cardio-respiratory problems, and neurological symptoms [10]. There is a wide difference in the prevalence of post-acute COVID-19, from 46% in Bangladesh to 87.4% in Italy [11,12]. Some researchers concluded that female gender and older age are important risk factors for eventual PACS [13,14], but others, found no link between these sociodemographic characteristics and the development of PACS [15]. There is a significant difference in the works of literature on whether or not risk factors for developing PACS include the existence of comorbidities [13,16], the type of symptoms that present during an acute illness [15,17], the length of hospitalization [11,15], and the amount of oxygen needed upon admission [18]. Cigarette smoking was not associated with PACS in some studies [19], while others found a strong association [20].

Ethiopia notified the first confirmed case of COVID-19 on March 13, 2020 [21]. The country recorded the largest number of COVID-19 confirmed cases in East Africa [2], implying a large number of patients with PACS. There are no post-COVID clinics in Ethiopia, nor is there a documented guideline for the management of post-COVID sequelae. There were no research articles in peer-reviewed journals measuring the burden of PACS in Ethiopia at the time this study was conceived. To alleviate these issues, we need to understand the prevalence and risk factors of PACS to establish effective management measures such as rehabilitation and support services. This may include physical therapy, occupational therapy, cognitive interventions, and mental health support to address the diverse range of symptoms and disabilities experienced by individuals with PACS.

As a result, this study aimed to assess the prevalence and associated risk factors of PACS among severe COVID-19 patients who were discharged alive from Millennium COVID-19 Care and Treatment Center, Addis Ababa, Ethiopia between June 12, 2020, and November 1, 2021.

Methodology

Study design and setting

A cross-sectional study design was used to assess the prevalence and associated risk factors of post-acute COVID-19 syndrome among severe COVID-19 patients who were discharged alive from Millennium COVID-19 Care Center, Addis Ababa, Ethiopia. Millennium COVID-19 Care Center (MCCC), was a makeshift hospital in Addis Ababa, the capital city of Ethiopia. The center was the biggest COVID-19 treatment facility in the country. It began giving service on June 2, 2020, and according to the center’s health management information system report (HMIS), as of November 1, 2021, a total of 6,760 patients were admitted and 5,580 patients were discharged alive.

Study participants

From adult patients (>18 years of age) who were admitted to MCCC with the diagnosis of Severe COVID-19 infection, confirmed by polymerase chain reaction (PCR) or rapid diagnostic test (RDT), those who were discharged alive between June 12, 2020, and November 1, 2021, were the study population.

Data collection tools and procedures

The socio-demographic profiles, past medical history including comorbidity, duration of symptoms before hospital admission, length of hospital stay, the maximum amount of oxygen required during hospital stay, acute manifestations of COVID-19, and baseline laboratory investigations were extracted from patient charts from January 2, 2023, to January 31, 2023. After obtaining verbal consent, a detailed telephonic interview was conducted with the study participants between February 1, 2023, and April 30, 2023, to record self-reported PACS symptoms and their characteristics, and self-assessment of current health status compared to the pre-COVID state. Data on COVID-19 vaccination history and current substance use were also collected during the telephone interview. The questionnaire was adapted from the W.H.O Global COVID-19 Clinical Platform Case Report Form (CRF) for Post COVID conditions (Post COVID-19 CRF) [22]. The English version of the questionnaire was first translated into Amharic, and a pilot study was done on 20 patients discharged from Eka Kotebe COVID-19 treatment center. A minor revision was made to the structure and language of the translated version based on the feedback from the participants in the pilot study. Data collectors were given training before the data collection. The collected data were entered into Epi-info software version 7 and then exported to Statistical Package for Social Sciences (SPSS) version 25 for cleaning and analysis. Individuals who could not be contacted after two attempts were excluded.

Sample size and statistical analysis

The sample size was determined for the prevalence by using the single population proportion formula and for the sociodemographic, clinical, and behavioral risk factors by using the double population proportion formula. The sample size calculated for the prevalence by using the single population proportion formula by considering p = 50%, as the prevalence of post-acute COVID syndrome is not known in Ethiopia, 95% confidence level (Zα/2 = 1.96), and a 5% margin of error yields the largest sample size. Since the source population is less than ten thousand (6760), a population correction formula was used and a 10% non-response rate was added to yield a final sample size of 400.

The medical record chart of patients who were admitted to the MCCC, along with the HMIS register book, is stored in an isolated corner within the medical record room of SPHMMC (St. Paul’s Hospital Millennium Medical College). Of the 5580 patients discharged alive from the center during the study period, 3576 of them were admitted with the diagnosis of Severe COVID-19. To obtain a representative sample, the sampling procedure followed a systematic random sampling. In systematic random sampling, the value of k (the sampling interval) is determined by dividing the population size (N) by the desired sample size (n) and rounding to the nearest whole number. The formula is as follows:

k=N/n

In this study, N (Study population) is 3576, and n (desired sample size) is 400. Using the above formula, k (sampling interval) is calculated to be 9. Every ninth patient discharged alive from MCCC with an admission diagnosis of severe COVID-19 and meeting the inclusion criteria is included in the study.

Frequency and cross-tabulation are used to summarize descriptive statistics of the data. The Mann–Whitney U test was used to compare skewed continuous variables. Associations between predictor variables and outcomes of interest are estimated using both bivariate analysis and binary logistic regression. Predictor variables with a p-value <0.25 in bivariate analyses are reported and included in the logistic regression. For the Binary Logistic regression, a 95% confidence interval for adjusted odds ratio (AOR) was calculated and variables with p-value ≤ 0.05 were considered as statistically associated with PACS.

Operational definitions

Severe COVID-19

Patients with clinical signs of severe pneumonia, ARDS, or sepsis ANDoxygen saturation less than 90% on room air; OR respiratory rate greater than 30.

Post-acute COVID-19 syndrome

Persistence of any sign or symptom that was developed during the acute COVID-19 illness for more than twelve weeks after hospital discharge.

Ethical consideration

The study was conducted after obtaining ethical clearance from St. Paul’s Hospital Millennium Medical College Institutional Review Board. Verbal informed consent was taken from study participants during the telephone interview and documented on the questionnaire after explaining the purpose and objectives of the study. Confidentiality of individual patient information is maintained by using code numbers instead of other identifiers and the information gained from the chart and phone call is used only for research purposes.

Results

Out of the 400 patients selected for the study, 20 patients (5%) died after hospital discharge, 14 patients (3.5%) refused to give consent, and 26 patients (6.5%) couldn’t be reached because their phone wasn’t working. The study included a total of 340 patients who were admitted to Millennium COVID-19 Care and Treatment Center with the diagnosis of severe COVID-19 pneumonia and discharged alive between June 12, 2020, and November 1, 2021 (Fig 1). The mean duration from hospital discharge to the interview was 25.6 (± 4.8) months.

Fig 1. Patient selection for this study.

Fig 1

Baseline sociodemographic and clinical characteristics

The majority (68.5%) of the study participants were male and the remaining 31.5% were females. The mean age at the time of admission to the center was 53.9 (±13.3 SD) years. The minimum age was 22 years and the maximum age was 85 years.

More than half of the patients (60%) have one or more comorbidities. As shown in Table 1, the most common comorbidity among the patients was diabetes (35.6%), followed by hypertension (34.1%), chronic heart disease (6.5%), asthma or COPD (5.6%), dyslipidemia (3.8%), HIV (3.2%), Cancer (1.5%), CLD (1.5%), stroke (1.2%), and CKD (0.3%).

Table 1. Comorbidity pattern of patients.

Comorbidity Frequency (Percent)
Diabetes 121 (35.6%)
Hypertension 116 (34.1%)
Chronic heart disease 22 (6.5%)
Asthma or COPD 19 (5.6%)
Dyslipidemia 13 (3.8%)
HIV 11 (3.2%)
Cancer 5 (1.5%)
Chronic liver disease 5 (1.5%)
Stroke 4 (1.2%)
Chronic kidney disease 1 (0.3%)

The median (IQR) duration of symptom onset before admission was 7 (5–10) days. The minimum was 1 day and the maximum was 30 days. The median (IQR) duration of hospital admission was 11 (7–15.75) days. The minimum was 2 days and the maximum was 39 days. The median (IQR) maximum amount of oxygen required during a hospital stay was 5 (3–7) liters. The minimum oxygen requirement was 1 liter and the maximum was 15 liters. A Mann-Whitney U test was conducted to compare the median scores of patients with and without PACS on duration of symptom onset before admission, length of hospital stay, and maximum amount of oxygen required during hospital stay. The test was statistically significant (p < 0.01) only for the length of hospital stay.

As shown in Table 2, the most common symptoms at presentation were cough (93.5%), followed by shortness of breath (82.1%), and fatigue (69.7%).

Table 2. Presenting symptoms.

Symptom Frequency (Percent)
Cough 318 (93.5%)
Shortness of breath 279 (82.1%)
Fatigue 237 (69.7%)
Fever 181 (53.2%)
Joint pain 166 (48.8%)
Headache 122 (35.9%)
Chest pain 103 (30.3%)
Loss of appetite 88 (25.9%)
Diarrhea 79 (23.2%)
Loss of taste 27 (7.9%)
Loss of smell 12 (3.5%)

In the complete blood count (CBC) parameter of the patients, there were two outlier results recorded on patients with chronic lymphocytic leukemia (CLL), who had the white blood cell (WBC) count of 350,000 cells/ μL and 49,000 cells/ μL. The mean WBC count after excluding these two results was 9,148 (±4,044 SD) cells/ μL. The patients had a low mean lymphocyte percentage (10.2%). The mean hemoglobin was 14.6 (±1.7 SD) gm/dl and the mean platelet count was 285,840 (±116,588 SD) cells/ μL.

Current status of study participants

Most (67.8%) of study participants visited a health facility at least once after their discharge from Millennium COVID-19 care and treatment center. The most common reason (59%) for the health facility visit was for follow-up of chronic disease and 15.7% of the reasons for hospital visit after discharge were not feeling well.

More than a third (38.1%) of the patients reported the persistence of at least one symptom after hospital discharge. As shown in Table 3, the most common symptoms that started during the acute COVID-19 infection and continued till the time of the interview in descending order were; fatigue (27.5%), Cough (15.3%), joint pain (14.1%), headache (11.9%), and shortness of breath (11.3%). Symptoms that were less commonly found were diarrhea (2.5%) and loss of appetite (2.5%).

Table 3. Symptoms that have persisted after hospital discharge.

Symptom Frequency (Percent)
Fatigue 88 (27.5%)
Cough 49 (15.3%)
Joint pain 45 (14.1%)
Headache 38 (11.9%)
Shortness of breath 36 (11.3%)
Sleep disturbance 35 (10.9%)
Chest pain 18 (5.6%)
Loss of appetite 18 (5.6%)
Loss of smell 18 (5.6%)
Diarrhea 8 (2.5%)
Loss of taste 8 (2.5%)

Close to one-third (29.4%) of the patients feel that their health condition has deteriorated after the COVID-19 infection. Forty-four (13.8%) of the patients claimed that, currently they are not able to do the daily activities they used to do before the infection which forced some of the patients to change and even quit their jobs. Currently, three (0.9%) and fifty-five (17.2%) of the patients smoke cigarettes and drink alcohol respectively. Of those who drink alcohol, most (40%) drink twice per month, followed by once per week (18.2%). Seven patients (12.7%) drink alcohol daily. Only 28.4% of the patients received at least one dose of vaccination.

Factors associated with PACS

Patient age, sex, presence of comorbidity, alcohol use, baseline hemoglobin level, initial presentation with fatigue or loss of appetite, and length of hospital stay were found to be associated with the development of PACS in the patients at a significant level of P <0.05. However, cigarette smoking, current vaccination status, mean day of presentation after symptom onset, and maximum amount of oxygen used during the hospital stay were not found to influence the development of post-acute COVID-19 syndrome (Table 4).

Table 4. Cross-tabulation of sociodemographic, clinical, and behavioral patterns with PACS.

Characteristics Has symptom Has no symptom P Value
Mean Age (years) 58.7 49.8 < 0.01
Sex 0.01
Male 74 (33.6%) 146 (66.4%)
Female 48 (48%) 52 (52%)
Comorbidity < 0.01
Yes 91 (48.4%) 97 (51.6%)
No 31 (23.5%) 101 (76.5%)
Specific comorbidity
Hypertension 56 (53.3%) 49 (46.7%) <0.01
Diabetes 48 (41.1%) 68 (58.6%) 0.36
Dyslipidemia 8 (66.7%) 4 (33.3%) 0.03
Chronic kidney disease 1 (100%) 0 (0%) 0.20
Chronic liver disease 3 (75%) 1 (25%) 0.12
Chronic heart disease 14 (87.5%) 2 (12.5%) <0.01
Cancer 4 (100%) 0 (0%) 0.01
HIV 6 (60%) 4 (40%) 0.14
Stroke 2 (66.7%) 1 (33.3%) 0.30
Asthma or COPD 8 (50%) 8 (50%) 0.31
Cigarette smoking 0 (0%) 3 (100%) 0.17
Alcohol use 28 (50.9%) 27 (49.1%) 0.03
Mean length of hospital stay (days) 14.0 11.2 <0.01
Symptom duration before admission 8.5 8.3 0.80
Mean maximum amount of oxygen 6.2 5.6 0.15
Mean baseline hemoglobin 14.3 14.8 <0.01
Current vaccination status 0.34
Vaccinated at least once 31 (34.1%) 60 (65.9%)
Not vaccinated 91 (39.7%) 138 (60.3%)
Fatigue at presentation 93 (41.9%) 129 (58.1%) 0.03
Loss of appetite at presentation 24 (28.6%) 60 (71.4%) 0.03

By using variables that have a p-value of <0.25 in the bivariate analysis, binary logisticregression was done after the model fitness test. Factors that were independently associated with the development of PACS were older age (AOR 1.04, 95% CI 1.02–1.07), female sex (AOR 1.82, 95% CI 1.00–3.29), presence of comorbidity (AOR 2.38, 95% CI 1.35–4.19), alcohol use (AOR 3.05, 95% CI 1.49–6.26), fatigue at presentation (AOR 2.18, 95% CI 1.21–3.95), and longer hospital stay (AOR 1.06, 95% CI 1.02–1.10). Higher hemoglobin level was found to decrease the risk of subsequent PACS (AOR 0.84, 95% CI 0.71–0.99) (Table 5).

Table 5. Crude and adjusted odds ratio of factors that have a significant association with PACS.

Characteristics COR (95% CI) P-Value AOR(95%CI) P-Value
Age in years 1.05 (1.03–1.08) <0.01 1.04 (1.02–1.07) <0.01
Female sex 1.82 (1.12–2.95) 0.01 1.82 (1.00–3.29) 0.04
Presence of comorbidity 3.05 (1.86–5.01) <0.01 2.38 (1.35–4.19) <0.01
Drinking alcohol 1.88 (1.05–3.38) 0.03 3.05 (1.49–6.26) <0.01
Length of hospital stay 1.06 (1.03–1.10) <0.01 1.06 (1.02–1.10) 0.01
Hemoglobin level 0.82 (0.71–0.95) <0.01 0.84 (0.71–0.99) 0.04
Fatigue at presentation 1.71 (1.03–2.85) 0.03 2.18 (1.21–3.95) <0.01
Loss of appetite 0.56 (0.32–0.96) 0.03 0.59 (0.31–1.09) 0.09

Discussion

As to the Authors’ knowledge, this is the first study that assessed the health consequences of COVID-19 at a two-year follow-up in patients who had severe COVID-19 pneumonia. 340 patients who were admitted to Millennium COVID-19 care and treatment center with the diagnosis of severe COVID-19 pneumonia were included in the study. The majority (68.5%) were males and the mean age was 53.9 (±13.3 SD) years. More than a third (38.1%) of the patients reported the persistence of at least one symptom after hospital discharge. The most common symptoms were fatigue (27.5%) and Cough (15.3%). Older age, female sex, presence of comorbidity, alcohol use, low baseline hemoglobin level, fatigue at presentation, and prolonged hospital stay were found to increase the odds of developing PACS. Thus, the study found that a significant proportion of patients don’t completely recover and continue to have some of the symptoms they developed during the acute infection.

The patients in this study were younger and males were more represented when compared to other similar studies. The mean age (53.9 years) at presentation was younger by six years in this study when compared to the cohort study conducted in Italy [20]. This is probably due to the demographic background of Ethiopia, where the proportion of the elderly population is lower than that in the Western world. The male-to-female ratio was 1.4:1 in the Bangladesh study, but the ratio is significantly higher (2.1:1) in this study [11].

The death rate after hospital discharge in this study was lower (5.8%) compared to a study done in Spain on patients who were admitted to Hospital for COVID-19. The study done in Spain found that 7.5% of the patients died within a mean follow-up period of one year [23].

The study participants in this study have a significantly higher level of comorbidity (60%) when compared to the cross-sectional study in Egypt on 430 patients found that 26.5% of patients reported that they have a chronic illness, and the Norwegian prospective cohort study, in which, 44% had comorbidities [16,24]. This significant difference in comorbidity is observed mainly because the other studies were done on all COVID-19 patients, and this study was done specifically on patients with severe COVID-19 pneumonia. Diabetes (35.6%), hypertension (34.1%), and chronic heart disease (6.5%) were the most common comorbidities in this study which is similar to the cohort studies done in Romania and England [25,26].

The prevalence of PACS in this study was 38.1%, which is lower than the finding in most of the studies, which were in the range of 46% in Bangladesh to 87.4% in Italy [11,12]. This may be because, in those studies, the maximum follow-up period was one year, but this study was conducted after a mean period of 25.6 months after hospital discharge and symptoms might have improved over time. The causes underlying these persistent symptoms following COVID-19 are not entirely understood. In addition to the direct effects of SARS-CoV-2, the immunological response to the virus is thought to have a role in the development of these long-term symptoms, presumably by supporting a continuing hyper-inflammatory process [27]. Molecular hydrogen inhalation had beneficial health effects in terms of improved physical (6-min walking test) and respiratory function in patients with PACS. Patients also noticed an improvement in fatigue after undergoing hyperbaric oxygen therapy and enhanced external counterpulsation. Muscle strength and physical function were improved after undergoing an 8-week biweekly physical therapy course including aerobic training, strengthening exercises, and diaphragmatic breathing techniques [28].

Fatigue is the most common (27.5%) symptom of PACS in this study, which is in concordance with the findings of most other similar studies [12,15,16]. Although the exact cause and pathogenesis of fatigue following COVID-19 is unknown, previous data from severe acute respiratory syndrome (SARS) suggests that lung diffusion capacity impairment, some extra-pulmonary causes, such as viral-induced myositis at initial presentation, cytokine disturbance, muscle wasting, and deconditioning, or corticosteroids myopathy, or a combination of these factors, may have contributed to the condition [29].

The second most common symptom in this study was cough (15.3%). This finding mirrors the findings of previous similar studies [11,19,30]. The mechanisms of cough after COVID-19 are multifactorial, including parenchymal sequelae and activation of the vagal sensory nerves, which leads to a cough hypersensitivity state [29].

In this study, 48% of female patients reported the presence of symptoms at the time of the interview. The female sex (AOR = 1.82, 95% CI 1.00–3.29, P = 0.04) was found to increase the risk of developing PACS. These findings are similar to other studies [13,14]. Various underlying processes explaining why females experience post-COVID symptoms to a larger extent than males are now being studied in the literature. Male and female biological differences in the expression of angiotensin-converting enzyme-2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) receptors, as well as immunological differences, such as lower production of pro-inflammatory interleukin-6 (IL-6) after viral infection in females, could explain the higher development of post-COVID symptoms [31].

Older age (AOR = 1.04, 95% CI 1.02–1.07, P: <0.01) was found to be a statistically significant predictor for the development of PACS. This is a similar finding to a study done in France where older age increased the risk of subsequent PACS (AOR = 1.49, 95% CI 1.05–2.17) [17].

Unlike the Bangladesh cohort study which showed patients with fever, cough, respiratory distress, and lethargy as the presenting features were more susceptible to develop PACS compared to other presenting features and the Indian study which showed diarrhea at presentation to be associated with PACS, the only presenting feature that was found to be significant in this study was fatigue (AOR = 2.18, 95% CI 1.21–3.95, P: <0.01) [11,32].

In this study, prolonged hospital stay was found to significantly increase the risk of PACS (AOR = 1.06, 95% CI 1.02–1.10, P = 0.01). A similar finding was observed in a study conducted in Spain which revealed that the number of days at the hospital was significantly associated with an increased risk of PACS [33].

Although the number of days between symptom onset and admission in the Indian study and the amount of oxygen requirement in the Egyptian study was found to determine PACS, this study found no association between those factors and PACS [18,32].

Another finding in our study was that COVID-19 vaccination was not found to be protective from PACS. This was also shown in previous studies [34].

The studies on the effect of smoking as a risk factor for developing post-acute COVID-19 syndrome showed conflicting results. A study conducted in Egypt showed that there is no significant association between cigarette smoking and post-acute COVID-19 syndrome [18], while a study conducted in Italy found a strong association between current active smoking and post-acute COVID-19 syndrome [20]. This study found no significant association between current cigarette smoking and PACS.

The effect of alcohol intake on the development of PACS is found to be significant (AOR = 3.05 [1.49–6.26], P: <0.01) in this study, which is a similar finding to the Mediterranean cohort study and the Bangladesh study [11,15].

The study has certain limitations. This is a single-center cross-sectional study which makes generalization of the findings from this research difficult. The findings of this study might have also suffered from the fact that it is done via a telephone interview which relies on self-reporting and can be subject to recall bias. Furthermore, incomplete documentation on patient charts is another limitation. This study did not consider the broad range of patient characteristics because of the paucity of data. Mainly, nutritional status which was included in most other studies isn’t included in the analysis of this research because of incomplete documentation in most of the charts. Future research should consider longitudinal multi-center studies to enhance generalizability, employ diverse data collection methods, and use a larger sample size to ensure the robustness of the findings.

Conclusion

The prevalence of PACS syndrome among severe COVID-19 patients who were discharged alive from Millennium COVID-19 Care and Treatment Center between June 12, 2020, and November 15, 2021, after a mean period since discharge of 25.6 months, was found to be 38.1%. Fatigue (27.5%) and cough (15.3%) were the most prevalent symptoms. Older age, female sex, presence of comorbidity, alcohol use, low baseline hemoglobin level, fatigue at presentation, and prolonged hospital stay were found to increase the odds of developing PACS.

These risk factors provide valuable insights for healthcare professionals in identifying individuals who may be more susceptible to post-acute COVID-19 syndrome and require targeted monitoring and care. The research findings emphasize the critical importance of long-term healthcare management for COVID-19 survivors. Multidisciplinary approaches involving healthcare providers from various specialties will be crucial in providing holistic care to post-acute COVID-19 syndrome patients.

Acknowledgments

We would like to thank our research participants who made this research complete. We are also grateful to the management and staff of St. Paul’s Hospital Millennium Medical College for their cooperation.

Data Availability

All raw data files are available from the Dryad repository database (https://datadryad.org/stash/share/X4rfM77vUc2yRwvIi0mI9FiyXbIla0CzHgJJdwJTv5g).

Funding Statement

The author(s) received no specific funding for this work.

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Decision Letter 0

Reaz Mahmud

24 Nov 2023

PONE-D-23-27462Assessment of the prevalence of post-acute COVID-19 syndrome and its associated risk factors among severe COVID-19 patients admitted to Millennium COVID-19 care center, Addis Ababa, EthiopiaPLOS ONE

Dear Dr. Elias,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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We look forward to receiving your revised manuscript.

Kind regards,

Reaz Mahmud, MBBS, FCPS (Medicine), MD (Neurology)

Academic Editor

PLOS ONE

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4. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

Thank you for submitting your article to Plos One.

Using the term 'frequency' instead of 'prevalence' for non-population-based studies is advised. Please brief the background section and add a conclusion to the abstract. The headings for the rationale and objective should be omitted, as they are part of the introduction. Please briefly discuss PACS's pathophysiology in the introduction and include the operational definitions of PACS and severe COVID-19 in the methods section. The telephone interview guide should be included in the supplement, and the categorization of fatigue and cough in the telephonic interview should be mentioned. Please describe how you identified the patients from the hospital records, briefly discuss the sampling technique used, and explain how you created the sampling frame and interval. A patient selection flow chart should be provided in the results section. For quantitative data, please use median (IQR) instead of mean and perform non-parametric tests. In the first paragraph of the discussion section, summarize the findings rather than presenting data. Please discuss the generalizability and limitations of the study and their implications in the discussion section. Lastly, please rewrite some references according to Plos guidelines and copyedit the manuscript for language correction.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript offers a detailed insight into the prevalence and risk factors associated with PACS in severe COVID-19 patients. The discussion effectively contextualizes the findings with previous literature, which is commendable. Key points include:

• Detailed exploration of the symptomatology, risk factors, and prevalence of PACS.

• Highlighting gender-based disparity in PACS presentation.

• Identifying significant associations like older age, prolonged hospital stay, and lifestyle factors.

Recommendations:

• Further elaborate on potential interventions or treatments for fatigue in PACS.

• Consider discussing the clinical implications of these findings for healthcare providers.

Minor grammatical errors were noticed in the manuscript. It would be beneficial for the authors to proofread the article for clarity.

Reviewer #2: The paper is well-written, and the methodology is robust. However, including additional details and clarifications in certain sections could enhance the overall quality and clarity of the research.

Here are some suggestions:

Introduction

Line 56, Consider adding a sentence or two explaining the potential impact of PACS on individuals, families, and society.

Line 59, 60. and 227, There is a discrepancy in the reference to prevalence percentages. It states "46% in Bangladesh to 81% in Italy," but later it mentions 87.4% in Italy. Please clarify this inconsistency.

Rationale

Line 74, Clarify the specific measures or interventions considered "effective management measures.

Methodology

Line 100, Provide more details about the adaptation process of the WHO Global COVID-19 Clinical Platform Case Report Form for Post-COVID conditions.

Results:

Line 128, Provide a percentage or proportion for the patients who died after hospital discharge (5.8%).

Lines 159-161, Consider providing more details on the health facility visits, such as the types of health facilities visited and the reasons for the visits.

Discussion:

Lines 200-210, The discussion is comprehensive and well-structured. Consider discussing potential limitations of the study, such as recall bias during telephone interviews.

Conclusion:

Lines 276-280, The conclusion summarizes the key findings well. Consider adding a brief statement about the implications of your findings for future research or public health interventions.

General comment:

Please review the manuscript for any potential grammatical errors to ensure the clarity and accuracy of the text before final submission.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: Yes: Dr Victor Abiola Adepoju

Reviewer #2: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2024 May 10;19(5):e0298409. doi: 10.1371/journal.pone.0298409.r002

Author response to Decision Letter 0


16 Dec 2023

PONE-D-23-27462

Assessment of the prevalence of post-acute COVID-19 syndrome and its associated risk factors among severe COVID-19 patients admitted to Millennium COVID-19 care center, Addis Ababa, Ethiopia

Dear Editor and Reviewers;

I hope this letter finds you well. I would like to express my gratitude for taking the time to review my manuscript. Your constructive feedback and comments have been invaluable in improving the quality and clarity of my work.

I would like to address the concerns and comments raised in your review. I have carefully considered each one of them and have made the necessary changes to the manuscript accordingly.

So please find the following comments and responses.

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming.

- I have revised the manuscript according to PLOS ONE’s style requirements.

2. Note from Emily Chenette, Editor in Chief of PLOS ONE, and Iain Hrynaszkiewicz, Director of Open Research Solutions at PLOS: Did you know that depositing data in a repository is associated with up to a 25% citation advantage (https://doi.org/10.1371/journal.pone.0230416)? If you’ve not already done so, consider depositing your raw data in a repository to ensure your work is read, appreciated and cited by the largest possible audience. You’ll also earn an Accessible Data icon on your published paper if you deposit your data in any participating repository (https://plos.org/open-science/open-data/#accessible-data).

- Raw data is deposited on Dryad: *https://datadryad.org/stash/share/X4rfM77vUc2yRwvIi0mI9FiyXbIla0CzHgJJdwJTv5g *https://doi.org/10.5061/dryad.fbg79cp2k

3. We suggest you thoroughly copyedit your manuscript for language usage, spelling, and grammar.

- The manuscript is now edited for language usage, spelling, and grammar.

Upon resubmission, please provide the following:

The name of the colleague or the details of the professional service that edited your manuscript.

- The manuscript is edited by Dr. Henok Fisseha.

A copy of your manuscript showing your changes by either highlighting them or using track changes (uploaded as a *supporting information* file)

- The copy of the original manuscript with track changes is uploaded as supporting information.

A clean copy of the edited manuscript (uploaded as the new *manuscript* file).

- A clean copy of the edited manuscript is uploaded.

4. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

- A major revision is made to the reference section. One retracted reference is removed. Few new references are added. Finally, the reference list is reorganized based on order and formatted according to PLOS guidelines.

Additional Editor Comments:

Thank you for submitting your article to Plos One.

Using the term 'frequency' instead of 'prevalence' for non-population-based studies is advised.

- Thank you for the comment. We used prevalence to measure the percentage of patients with PACS among the COVID-19 affected population.

Please brief the background section and add a conclusion to the abstract.

- Background section is briefed and conclusion added to the abstract.

The headings for the rationale and objective should be omitted, as they are part of the introduction.

- Headings for rationale and objective are omitted.

Please briefly discuss PACS's pathophysiology in the introduction and include the operational definitions of PACS and severe COVID-19 in the methods section.

- PACS pathophysiology is added to the introduction section and operational definitions of PACS and severe COVID-19 are added in the methods section.

The telephone interview guide should be included in the supplement, and the categorization of fatigue and cough in the telephonic interview should be mentioned.

- Both the English and Amharic versions of the telephonic interview guide are now attached in the supporting information now. We only used the study participants’ subjective response of whether the fatigue or cough that started during the acute illness persisted until the time of interview or not. We didn’t further categorized fatigue and cough.

Please describe how you identified the patients from the hospital records, briefly discuss the sampling technique used, and explain how you created the sampling frame and interval.

- The procedures used to identify the patients from hospital records, the sampling technique used, how sampling frame and interval was created are now included in the methodology section.

A patient selection flow chart should be provided in the results section.

- Patient selection flow chat is included in the results section now.

For quantitative data, please use median (IQR) instead of mean and perform non-parametric tests.

- For quantitative data, except age, median (IQR) is used and Mann-Whitney U test is performed.

In the first paragraph of the discussion section, summarize the findings rather than presenting data.

- First paragraph of the discussion is now revised. Detailed data is removed a summary of the findings is included.

Please discuss the generalizability and limitations of the study and their implications in the discussion section.

- Limitations and generalizability of the study is included now in the discussion section.

Lastly, please rewrite some references according to PLOS guidelines and copyedit the manuscript for language correction.

- Manuscript is edited for language correction and reference list is updated according to PLOS guidelines.

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

- Thank you for the positive response.

________________________________________

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

- Thank you for the positive response.

________________________________________

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

- Raw data is deposited on the Dryad repository now.

________________________________________

4. Is the manuscript presented in an intelligible fashion and written in Standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

- Thank you for the positive response.

________________________________________

5. Review Comments to the Author

Reviewer #1: The manuscript offers a detailed insight into the prevalence and risk factors associated with PACS in severe COVID-19 patients. The discussion effectively contextualizes the findings with previous literature, which is commendable. Key points include:

• Detailed exploration of the symptomatology, risk factors, and prevalence of PACS.

• Highlighting gender-based disparity in PACS presentation.

• Identifying significant associations like older age, prolonged hospital stay, and lifestyle factors.

- Thank you for the positive response.

Recommendations:

• Further elaborate on potential interventions or treatments for fatigue in PACS.

- Effective interventions and treatments for fatigue in PACS is now included.

• Consider discussing the clinical implications of these findings for healthcare providers.

- The clinical implications of these findings for healthcare providers in now included in the conclusion section.

Minor grammatical errors were noticed in the manuscript. It would be beneficial for the authors to proofread the article for clarity.

- The article is now edited for clarity and grammatical errors.

Reviewer #2: The paper is well-written, and the methodology is robust.

- Thank you for the positive response.

However, including additional details and clarifications in certain sections could enhance the overall quality and clarity of the research.

Here are some suggestions:

Introduction

Line 56, Consider adding a sentence or two explaining the potential impact of PACS on individuals, families, and society.

- The Economic impact of PACS is now included with a new reference.

Line 59, 60, and 227, there is a discrepancy in the reference to prevalence percentages. It states "46% in Bangladesh to 81% in Italy," but later it mentions 87.4% in Italy. Please clarify this inconsistency.

- Thank you for noticing the discrepancy. These are two separate studies conducted in Italy. Because the later one showed a higher prevalence, the first article is omitted.

Rationale

Line 74, Clarify the specific measures or interventions considered "effective management measures.

- Specific measures or interventions are now briefly explained.

Methodology

Line 100, Provide more details about the adaptation process of the WHO Global COVID-19 Clinical Platform Case Report Form for Post-COVID conditions.

- The adaptation process is now discussed in the data collection tools and procedures sub section of the methodology.

Results:

Line 128, Provide a percentage or proportion for the patients who died after hospital discharge (5.8%).

- Percentage of patients who died after hospital discharge is now include in the results section.

Lines 159-161, consider providing more details on the health facility visits, such as the types of health facilities visited and the reasons for the visits.

- The health facilities are either clinic, health center, or hospital. The most common reason (59%) for the health facility visit was for follow-up of chronic disease like diabetes or hypertension, and 15.7% of the reasons for hospital visit after discharge were not feeling well.

Discussion:

Lines 200-210, the discussion is comprehensive and well-structured. Consider discussing potential limitations of the study, such as recall bias during telephone interviews.

- Limitations of the study are now included at the end of the results section.

Conclusion:

Lines 276-280, The conclusion summarizes the key findings well. Consider adding a brief statement about the implications of your findings for future research or public health interventions.

- The implications of the findings for future research and public health intervention are now included at the end of the discussion section and the conclusion part.

General comment:

Please review the manuscript for any potential grammatical errors to ensure the clarity and accuracy of the text before final submission.

- The manuscript is now checked for grammatical errors.

________________________________________

Attachment

Submitted filename: Response to Reviewers.docx

pone.0298409.s001.docx (21.3KB, docx)

Decision Letter 1

Robert Jeenchen Chen

3 Jan 2024

PONE-D-23-27462R1Assessment of the prevalence of post-acute COVID-19 syndrome and its associated risk factors among severe COVID-19 patients admitted to Millennium COVID-19 care center, Addis Ababa, EthiopiaPLOS ONE

Dear Dr. Elias,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Feb 17 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Robert Jeenchen Chen, MD, MPH

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

Please revise and shorten the Title.

There is no need to specify the city name in the Title unless necessary.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have addressed all the issues raised by the reviewers and current iteration merit publication after some editorial polishing of the paper. Good job

Reviewer #2: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: No

Reviewer #2: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2024 May 10;19(5):e0298409. doi: 10.1371/journal.pone.0298409.r004

Author response to Decision Letter 1


4 Jan 2024

PONE-D-23-27462R1

Assessment of the prevalence of post-acute COVID-19 syndrome and its associated risk factors among severe COVID-19 patients admitted to Millennium COVID-19 Care Center, Addis Ababa, Ethiopia

Dear Editor and Reviewers;

I hope this letter finds you well. I would like to express my gratitude for taking the time to review my manuscript. Your constructive feedback and comments have been invaluable in improving the quality and clarity of my work.

I would like to address the concerns and comments raised in your review. I have carefully considered each one of them and have made the necessary changes to the manuscript accordingly.

So please find the following comments and responses.

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please review your reference list to ensure that it is complete and correct.

- I've re-checked the reference list and found it to be complete and correct.

2. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references.

- No retracted papers are cited in the current submission.

3. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

- No changes are made to the reference list.

Additional Editor Comments:

Please revise and shorten the Title.

There is no need to specify the city name in the Title unless necessary.

Thank you for the comment. The title is now revised to “Determinants of Post-acute COVID-19 Syndrome among hospitalized severe COVID-19 Patients: A 2-year follow-up study”

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

- Thank you for the positive response.

________________________________________

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

- Thank you for the positive response.

________________________________________

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

- Thank you for the positive response.

________________________________________

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

- Thank you for the positive response.

________________________________________

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

- Thank you for the positive response.

________________________________________

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have addressed all the issues raised by the reviewers and current iteration merit publication after some editorial polishing of the paper. Good job

Reviewer #2: (No Response)

- Thank you for the positive response.

Attachment

Submitted filename: Response to Reviewers.docx

pone.0298409.s002.docx (17.4KB, docx)

Decision Letter 2

Robert Jeenchen Chen

25 Jan 2024

Determinants of Post-acute COVID-19 Syndrome among hospitalized severe COVID-19 Patients: A 2-year follow-up study

PONE-D-23-27462R2

Dear Dr. Elias,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Robert Jeenchen Chen, MD, MPH

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: The authors have diligently addressed all concerns. They confirm the reference list's accuracy and no citation of retracted papers. Appreciate their thoroughness.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

**********

Acceptance letter

Robert Jeenchen Chen

29 Apr 2024

PONE-D-23-27462R2

PLOS ONE

Dear Dr. Elias,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

* All relevant supporting information is included in the manuscript submission,

* There are no issues that prevent the paper from being properly typeset

If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps.

Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

If we can help with anything else, please email us at customercare@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Robert Jeenchen Chen

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    Attachment

    Submitted filename: Response to Reviewers.docx

    pone.0298409.s001.docx (21.3KB, docx)
    Attachment

    Submitted filename: Response to Reviewers.docx

    pone.0298409.s002.docx (17.4KB, docx)

    Data Availability Statement

    All raw data files are available from the Dryad repository database (https://datadryad.org/stash/share/X4rfM77vUc2yRwvIi0mI9FiyXbIla0CzHgJJdwJTv5g).


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