Clinical Epidemiology of Hospitalized Patients With Coronavirus Disease 2019 (COVID-19) in Japan: Report of the COVID-19 Registry Japan

Gender differences and mental distress during COVID-19: a cross-sectional study in Japan

BACKGROUND

To identify risk factors for mental distress and investigate whether the factors were different between men and women during the coronavirus disease 2019 (COVID-19), using KOKOROBO data, which is an online platform that aims to facilitate access to mental health services.

METHODS

We used baseline data on KOKOROBO users 13 years of age or older in Japan who accessed it from October 11, 2021, to April 6, 2023, excluding those receiving treatment for mental health problems. Global severity, based on the most severe measure on Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and Insomnia Severity Index (ISI), was analyzed using multivariable logistic regression with baseline characteristics for each gender, and for under 30 and 30 years of age or older in women. We conducted the same analysis of suicidal ideation for each gender.

RESULTS

In the 686 men and 1274 women, 117 (17.1%) and 100 (7.8%) had minimal global severity respectively, and the rest suffered from mental distress to some extent. For women, ages under 30 years (adjusted OR (aOR): 0.352, 95%CI: 0.231-0.539, P < 0.001), marriage (aOR: 0.453, 95%CI: 0.274-0.746, P = 0.002), and concerns about COVID-19 infection were associated with global severity, while having children (aOR: 0.509, 95% CI: 0.284-0.909, P = 0.023) and decrease of going out during the COVID-19 pandemic had a protective effect on global severity and suicidal ideation for men, respectively. Living with family was a risk factor for mental distress in unmarried women over 30 years of age. Less communication with family or others and responding to the questionnaire late at night (00:00-05:59) were associated with severe global severity in both genders.

CONCLUSIONS

Age, living arrangement, marriage, having children, concerns about COVID-19 infection, and lifestyle changes during the COVID-19 pandemic had gender-specific effects on mental distress, while frequent communication and regular life rhythm maintained mental health in both genders. Young women and, unmarried middle-aged women living with their families tended to experience mental distress during the COVID-19 pandemic.

TRIAL REGISTRATION

The Ethics Committee of the National Center of Neurology and Psychiatry approved this study (approval number B2020141) on April 15, 2021.

Development and Validation of Claims-based Algorithms for Identifying Hospitalized Patients With COVID-19 and Their Severity in 2020 and 2021

BACKGROUND

This study aimed to develop and validate claims-based algorithms for identifying hospitalized patients with coronavirus disease 2019 (COVID-19) and disease severity.

METHODS

We used claims data including all patients at the National Center for Global and Medicine Hospital between January 1, 2020, and December 31, 2021. The claims-based algorithms for three statuses with COVID-19 (hospitalizations, moderate or higher status, and severe status) were developed using diagnosis codes (International Classification of Diseases, 10th revision code: U07.1, B34.2) and relevant medical procedure code. True cases were determined using the COVID-19 inpatient registry and electronic health records. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each algorithm at 6-month intervals.

RESULTS

Of the 75,711 total patients, the number of true cases was 1,192 for hospitalizations, 622 for moderate or higher status, and 55 for severe status. The diagnosis code-only algorithm for hospitalization had sensitivities 90.4% to 94.9% and PPVs 9.3% to 19.4%. Among the algorithms consisting of both diagnosis codes and procedure codes, high sensitivity and PPV were observed during the following periods: 93.9% and 97.1% for hospitalization (January-June 2021), 90.4% and 87.5% for moderate or higher status (July-December 2021), and 92.3% and 85.7% for severe status (July-December 2020), respectively. Almost all algorithms had specificities and NPVs of approximately 99%.

CONCLUSION

The diagnosis code-only algorithm for COVID-19 hospitalization showed low validity throughout the study period. The algorithms for hospitalizations, moderate or higher status, and severe status with COVID-19, consisting of both diagnosis codes and procedure codes, showed high validity in some periods.

Comparison of clinical characteristics and severity of COVID-19 with or without viral co-infection in hospitalized children

BACKGROUND

Co-infection with other pathogens can alter the severity and clinical outcomes of viral infections. However, the information regarding viral co-infections in pediatric coronavirus disease 2019 (COVID-19) cases is still limited.

METHODS

This is a nationwide, retrospective cohort study using the data from the COVID-19 Registry Japan. The pediatric (<18 years), laboratory confirmed, hospitalized COVID-19 patients in the Omicron variant of concern predominant period (January 2022 to January 2024) were included. Co-infection was investigated by multiplex PCR. We compared clinical characteristics, symptoms, severity, and outcomes between children with and without co-infection.

RESULTS

Among 245 hospitalized pediatric COVID-19 patients, 78 (31.8 %) had co-infections. The patient backgrounds of the "co-infection" and "SARS-CoV-2 alone" groups were similar, although age distribution was different, with a lower number of patients over 12 years in the co-infection group (n = 2, 2.6 % vs. n = 29, 17.4 %; P < 0.001). Among the patients with co-infection, the most common pathogen was enterovirus/rhinovirus (51.3 %), followed by parainfluenza virus (23.1 %) and adenovirus (12.8 %). Patients with co-infection more commonly had respiratory symptoms, including SpO2 < 96 %, shortness of breath, runny nose, and wheezing. Requirement of non-invasive oxygen support was higher in the co-infection group (n = 27, 34.6 % vs. n = 28, 16.8 %, P = 0.006). By multivariable logistic regression analysis, co-infection and presence of any comorbidity were identified as significant risk factors for necessity of oxygen therapy (odds ratio [95 % confidence interval] 2.44 [1.29-4.63] and 3.99 [2.07-7.82], respectively).

CONCLUSIONS

Viral co-infection may increase the risk of respiratory distress in pediatric COVID-19 patients.

Association Between COVID-19 and Diabetes Management Indices in Japanese Type 2 Diabetes Mellitus Patients: A Single-Center, Retrospective Study

Purpose

The aim of the study was to determine the association between coronavirus disease 2019 (COVID-19) infection and diabetes management indices in patients with type 2 diabetes mellitus.

Patients and Methods

A single-center, retrospective, observational study of patients with type 2 diabetes mellitus at Kenwakai Hospital (Nagano, Japan) was conducted. Data of 95 patients (mean age, 72 ± 12 years; men, 67.4%) who visited between March 1, 2019 and February 28, 2022 were obtained from the hospital's electronic information system. COVID-19 was diagnosed by a chemiluminescent enzyme immunoassay (CLEIA).

Results

There was no association between COVID-19 infection and age, sex, hemodialysis treatment status, or the Charlson Comorbidity Index. After adjustment for possible confounding factors, the incidence of COVID-19 infection was significantly correlated with HbA1c ≥7.0% (odds ratio [OR], 5.51; 95% confidence interval [CI], 1.30-23.26).

Conclusion

The results suggest an association between high HbA1c levels and COVID-19 infection in patients with type 2 diabetes mellitus. Appropriate management of diabetes mellitus, focusing on HbA1c levels, may help prevent COVID-19 infection and severe disease after infection.

Comparative Study of Blood Neopterin and Biopterins in Patients with COVID-19 and Secondary Bacterial Infection

Background/Objectives: As COVID-19 can be severe, early predictive markers of both severity and onset of secondary bacterial infections are needed. This study first examined changes over time in the levels of plasma neopterin (NP) and biopterins (BPs), among others, in patients with COVID-19 and then in those with secondary bacterial infection complications. Methods: Fifty-two patients with COVID-19 admitted to two tertiary care centers were included. They were divided into a severe group (intubated + mechanical ventilation) (n = 10) and a moderate group (non-intubated + oxygen administration) (n = 42), and changes over time in plasma NP, plasma BPs, IFN-γ, lymphocyte count, CRP, and IL-6 were investigated. Four of the patients in the severe group (n = 10) developed secondary bacterial infections during treatment. Plasma NP and plasma BPs of patients with bacterial sepsis (no viral infection) (n = 25) were also examined. Results: The plasma NP, IL-6, CRP, and SOFA levels were significantly higher in the severe group, while the IFN-γ level and lymphocyte count were significantly lower. The higher plasma NP in the severe group persisted only up to 1 week after symptom onset. The plasma BPs were higher in complications of bacterial infection. Conclusions: The timing of sample collection is important for assessing severity through plasma NP, while plasma BPs may be a useful diagnostic tool for identifying the development of secondary bacterial infection in patients with COVID-19. Further investigation is needed to clarify the mechanism by which NP and BPs, which are involved in the same biosynthetic pathway, are differentially activated depending on the type of pathogen.

Efficacy of corticosteroid therapy for oxygen-free coronavirus disease 2019-derived pneumonia

Corticosteroid therapy for oxygen-free coronavirus disease 2019 (COVID-19) is not recommended due to its negative prognostic impact, but the efficacy of corticosteroids when limited to COVID-19 pneumonia is unclear. We aimed to evaluate the efficacy of corticosteroid monotherapy for patients with COVID-19 pneumonia without supplemental oxygen. We retrospectively reviewed patients with oxygen-free COVID-19 pneumonia at our institute between September 2020 and August 2021 and assessed the use of corticosteroids and the timing of initiation. We classified the patients into the following 2 groups: those who were initiated corticosteroids without developing respiratory failure (early steroid group) and those who were not (standard of care [SOC] group). We used inverse probability of treatment weighting (IPW) to balance between the groups. The primary outcome was the incidence of respiratory failure. A total of 144 patient records were reviewed; 63 patients were in the early steroid group and 81 patients were in the SOC group. Of all patients, 14 (22.2%) and 27 (33.3%) patients in the early steroid and SOC group, respectively, required supplemental oxygen (P = .192). After adjusted by the IPW method, 10 (16.0%) and 32 (40.1%) patients in the early steroid and SOC groups, respectively, required supplemental oxygen (P = .004). The logistic regression analysis indicated that early corticosteroid use was significantly associated with a decreased incidence of respiratory failure (odds ratio; 0.17, 95% confidence intervals; 0.06-0.46, P < .001). Corticosteroid monotherapy may suppress the development of exacerbation requiring oxygen supply in patients with oxygen-free COVID-19 pneumonia.

Association between COVID-19 severity and relatively high serum adiponectin levels at the time of admission

At the beginning of 2020, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to epidemics worldwide. Obesity and visceral fat accumulation have been reported to be independent risk factors for severe COVID-19. Several reports have focused on the levels of adipocytokines/adipokines, including adiponectin (APN), which is exclusively secreted from adipocytes, although the importance of these factors in acute disease conditions remains unclear. Therefore, we investigated the relationship between serum adiponectin levels and COVID-19 severity. Patients with COVID-19 who were admitted to Sumitomo Hospital (Osaka, Japan) from May through October 2021 were included. A total of 107 patients were enrolled in this study. We obtained the anthropometric and clinical laboratory data of the patients at the time of admission and examined the associations between various parameters and COVID-19 severity. The mean period from onset to admission was 6.5 ± 2.8 days. We divided the patients into "non-severe" (mild, moderate-I and moderate-II) (n = 80) and "severe" (n = 27) groups. The "severe" patients were significantly older than "non-severe" patients. Additionally, no significant differences were observed in BMI, sex, or the period from onset to admission. The serum adiponectin levels of "severe" patients at the time of admission were significantly greater than those of "non-severe" patients even after adjusting for age, sex, and BMI. These results suggest that the serum APN levels at the time of admission can predict COVID-19 severity. However, further investigations on the changes in APN levels in acute diseases are needed.

Pulmonary function and chest CT abnormalities 3 months after discharge from COVID-19, 2020-2021: A nation-wide multicenter prospective cohort study from the Japanese respiratory society

BACKGROUND

No comprehensive analysis of the pulmonary sequelae of coronavirus disease 2019 (COVID-19) in Japan based on respiratory function tests and chest computed tomography (CT) has been reported. We evaluated post-COVID-19 conditions, especially focusing on pulmonary sequelae assessed by pulmonary function tests and chest CT.

METHODS

For this prospective cohort study, we enrolled 1069 patients who presented pneumonia at the time of admission in 55 hospitals from February 2020 to September 2021. Disease severity was classified as moderateⅠ, moderate II, and severe, defined primarily according to the degree of respiratory failure. The data on post-COVID-19 conditions over 12 months, pulmonary function, and chest CT findings at 3 months were evaluated in this study. Additionally, the impact of COVID-19 severity on pulmonary sequelae, such as impaired diffusion capacity, restrictive pattern, and CT abnormalities, was also evaluated.

RESULTS

The most frequently reported post-COVID-19 conditions at 3 months after COVID-19 were muscle weakness, dyspnea, and fatigue (48.4%, 29.0%, and 24.7%, respectively). The frequency of symptoms gradually decreased over subsequent months. In pulmonary function tests at 3 months, the incidence of impaired diffusion capacity and restrictive pattern increased depending on disease severity. There also were differences in the presence of chest CT abnormalities at the 3 months, which was markedly correlated with the severity.

CONCLUSION

We reported a comprehensive analysis of post-COVID-19 condition, pulmonary function, and chest CT abnormalities in Japanese patients with COVID-19. The findings of this study will serve as valuable reference data for future post-COVID-19 condition research in Japan.

Blood perfusion with polymyxin B immobilized columns in patients with COVID-19 requiring oxygen therapy

Extracorporeal blood purification with polymyxin B immobilized fiber column direct hemoperfusion (PMX-DHP), is reported to be effective in treating COVID-19 pneumonitis with oxygen demand. This multicenter prospective study evaluated the efficacy and safety of PMX-DHP in oxygen-requiring patients with COVID-19 admitted between September 28, 2020, and March 31, 2022. The primary endpoint was the percentage of clinical improvement 15 days after treatment. The secondary endpoint was the percentage of worsened disease status. Data from the COVID-19 patient registry were used for the synthetic control group. The improvement rate on Day 15 did not differ between PMX-treated patients and controls; however, the deterioration rate was 0.38 times lower in the PMX-treated group, and the death rates on Day 29 were 0 and 11.1% in the PMX-treated and control groups, respectively. The PMX group showed a 0.73 times higher likelihood for reduced intensive care demand, as 16.7% of PMX-treated patients and 22.8% of controls worsened. After treatment blood oxygenation improved, urinary β2-microglobulin and liver-type fatty acid-binding protein showed significant decreases, and IL-6 decreased once during treatment but did not persist. In this study, PMX treatment effectively prevented the worsening of COVID-19 pathology, accompanied by improved oxygenation. PMX treatment to remove activated cells may effectively improve patient outcomes.

Impact of the COVID-19 Infection on Head and Neck Cancer Treatment During Hospitalization

Objective The after-effects of coronavirus disease 2019 (COVID-19) infection are still unknown; therefore, we investigate the possibility that COVID-19 may interrupt cancer treatment and impact prognosis. Methods We examined the characteristics, prognosis, and changes in treatment options before and after COVID-19 in 11 head and neck cancer patients who were infected with COVID-19 after admission for cancer treatment at Gifu University Hospital. These patients were compared to 110 patients unaffected by COVID-19 during the same period. To identify the effects of COVID-19 on the cancer treatment sequence, we examined the rates of overall survival, progression-free survival, and completion, as well as radiation dosage in radiotherapy and cisplatin dosage in chemoradiotherapy. Results All 11 patients with COVID-19 had their planned cancer treatment postponed or interrupted. There was no significant difference in overall or progression-free survival compared to patients without COVID-19. Notably, only 3/6 of the COVID-19-affected patients completed radiotherapy compared to 42/46 unaffected patients. The ratio of actual radiation dose to planned dose was significantly impaired in COVID-19 affected patients group (98.3% vs. 88.6%). Cisplatin dosage in chemoradiation was not significantly different in either the radical (100 mg/m2, every three weeks) or adjuvant (40 mg/m2, every one week) treatment groups. Conclusion COVID-19 infection in head and neck cancer patients had no apparent impact on cancer prognosis. However, when restricted to irradiation, the treatment completion rate and the ratio of planned to actual dose decreased significantly, underscoring the impact of COVID-19 infection on cancer treatment. The difference in irradiation may affect the success of patients' treatment going forward, and it should be explored whether irradiation can be continued without delay.

Status of COVID-19 Patients Treated With Extracorporeal Membrane Oxygenation in Japan: Nationwide Database Analysis

Background The report of epidemiological data on coronavirus disease 2019 (COVID-19) patients treated using extracorporeal membrane oxygenation (ECMO) in Japan has been limited. Our study seeks to fill the existing gap in knowledge by providing an in-depth analysis of the clinical epidemiological characteristics and diverse medical outcomes of COVID-19 patients treated with ECMO in Japan. Methods This study used the COVID-19 Registry Japan nationwide database. We included patients aged 18 years or older enrolled between March 17, 2020, and February 1, 2022, with traceable ECMO data. The items on clinical epidemiological characteristics and various medical outcomes were collected. Statistical analysis included a median and interquartile range (IQR) for continuous variables and frequencies for categorical variables. Results The number of participating hospitals was 731, and the number of patients enrolled for analysis was 49,590. Of these, 196 (0.4%) patients received ECMO. Hospital mortality was 33.2%, and discharge to home was 23.0% in the ECMO group. The complications during hospitalization included pneumothorax (9.7%), seizures (4.1%), stroke (4.6%), and pulmonary thromboembolism (2.0%). At discharge, 38.3% had worsened self-care ability, and 38.8% had worsened ambulatory function. Conclusions The results of ECMO treatment in Japan showed that the mortality and complication rates were well-controlled compared with those worldwide.

Characteristics and prognosis of patients with COVID-19 and hematological diseases in Japan: a cross-sectional study

The Japanese Society of Hematology performed an observational cross-sectional study to clarify the morbidity, prognosis, and prognostic factors in patients with COVID-19 with hematological diseases (HDs) in Japan. The study included patients with HDs who enrolled in our epidemiological survey and had a COVID-19 diagnosis and a verified outcome of up to 2 months. The primary endpoints were characteristics and short-term prognosis of COVID-19 in patients with HDs. A total of 367 patients from 68 institutes were enrolled over 1 year, and the collected data were analyzed. The median follow-up among survivors was 73 days (range, 1-639 days). The 60-day overall survival (OS) rate was 86.6%. In the multivariate analysis, albumin ≤ 3.3 g/dL and a need for oxygen were independently associated with inferior 60-day OS rates (hazard ratio [HR] 4.026, 95% confidence interval (CI) 1.954-8.294 and HR 14.55, 95% CI 3.378-62.64, respectively), whereas 60-day survival was significantly greater in patients with benign rather than malignant disease (HR 0.095, 95% CI 0.012-0.750). Together, these data suggest that intensive treatment may be necessary for patients with COVID-19 with malignant HDs who have low albumin levels and require oxygen at the time of diagnosis.

Real-world effectiveness of full and booster mRNA vaccination for coronavirus disease 2019 against disease severity during the delta- and omicron-dominant phases: A propensity score-matched cohort study using the nationwide registry data in Japan

BACKGROUND

To date, few studies from the Asian region have reported the effectiveness of messenger ribonucleic acid coronavirus disease 2019 (COVID-19) vaccines against disease progression and death after hospitalization.

METHODS

We evaluated the data from the COVID-19 registry in Japan during the delta- and omicron-dominant phases. A propensity score-matched cohort study was conducted between the incompletely (0-1 dose) and fully (2 doses) vaccinated groups during the delta-dominant phase and among the incompletely, fully, and booster (3 doses) vaccinated groups during the omicron-dominant phase.

RESULTS

In the delta-dominant phase, 411 pairs were matched. The fully vaccinated group showed a significantly lower oxygen supplementation rate (24.1 % vs. 41.1 %, p < 0.001) but little difference in the mortality rate (2.2 % vs. 2.9 %, p = 0.66). In the omicron-dominant phase, 1494 pairs from the incompletely and fully vaccinated groups, and 425 pairs from the fully and booster vaccinated groups were matched. Full vaccination reduced both the oxygen supplementation rate (18.6 % vs 25.7 %, p < 0.001) and mortality rate (0.7 % vs 2.3 %, p < 0.001). Booster vaccination showed little difference in either the rate of oxygen supplementation (21.2 % vs. 24.7 %, p = 0.25) or mortality (1.2 % vs. 2.6 %, p = 0.21) compared with full vaccination.

CONCLUSIONS

Full vaccination reduced disease severity during the delta- and omicron-dominant phases; booster vaccination did not further enhance the protective effects against disease progression during the omicron-dominant phase compared to full vaccination. Future vaccine strategies and policy decisions should consider preventing infection or disease progression in the target population, as well as the characteristics of the dominant variant in that phase.

Real-world prescription of anti-COVID-19 drugs in hospitalized patients with COVID-19 in Japan

OBJECTIVE

Prescription trends and patterns of anti-COVID-19 drugs in hospitalized patients were examined based on real world data to understand the use of anti-COVID-19 drugs in clinical practice in Japan.

DESIGN

The longitudinal and cross-sectional study was conducted utilizing data from January 1, 2019 to December 31, 2021 of the MID-NET® medical information database, which stored the electronic medical records, administrative claim data, and diagnosis procedure combination data of patients in Japan.

PARTICIPANTS

Hospitalized patients with a COVID-19-related diagnosis who received at least one anti-COVID-19 drug between April 1, 2020 and December 31, 2021.

EXPOSURES

The following 14 drugs were included in this study: remdesivir, baricitinib, combination product of casirivimab and imdevimab, favipiravir, dexamethasone, ivermectin, azithromycin, nafamostat mesylate, camostat mesylate, ciclesonide, tocilizumab, sarilumab, combination product of lopinavir and ritonavir, and hydroxychloroquine.

RESULTS

We identified 5,717 patients hospitalized with COVID-19 and prescribed at least one anti-COVID-19 drug. The entire cohort generally included patients over 41-50 years and more males. The most common prescription pattern was dexamethasone monotherapy (22.9%), followed by the concomitant use of remdesivir and dexamethasone (15.0%), azithromycin monotherapy (15.0%), remdesivir monotherapy (10.2%), and nafamostat mesylate monotherapy (8.5%). However, an often prescribed anti-COVID-19 drug differed depending on the period.

CONCLUSIONS AND RELEVANCE

This study revealed the real-world situation of anti-COVID-19 drug prescriptions in hospitalized COVID-19 patients in Japan. A prescribed drug would depend on the latest scientific evidence, such as efficacy, safety, and approval status, at the time of prescription. Understanding the prescription of anti-COVID-19 drugs will be important for providing the most up-to-date treatments to patients and evaluating the benefit and/or risk of anti-COVID-19 drugs based on the utilization of an electronic medical record database.

Severe Refractory Diarrhea Associated with COVID-19: A Case Report

Introduction

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is frequently associated with various gastrointestinal symptoms, including abdominal pain, vomiting, and diarrhea. Moreover, several cases of refractory diarrhea have been reported after COVID-19 recovery. Herein, we present a case of severe refractory diarrhea associated with COVID-19.

Case Presentation

A 50-year-old man with no comorbidities was admitted to our hospital with SARS-CoV-2 pneumonia. His respiratory status deteriorated, and ventilatory management, including extracorporeal membrane oxygenation, was needed. The patient's respiratory condition improved, resulting in a transfer to another hospital for rehabilitation. However, the patient developed diarrhea that worsened to 6,000-7,000 mL/day, and he was transferred to our hospital. We diagnosed the patient with enterocolitis caused by cytomegalovirus infection and treated him with ganciclovir on day 5 after transfer to our hospital. The diarrhea did not improve. We suspected enterocolitis associated with COVID-19 and administered a methylprednisolone pulse (intravenous injection, 1,000 mg/day for 3 days) on day 10 after transfer, resulting in a marked improvement in his symptoms. The prednisolone dose was tapered, and no recurrence of diarrhea was observed thereafter.

Conclusion

The prevalence of COVID-19-associated enterocolitis is low, and the pathogenesis of the disease remains unclear. Prednisolone administration should be considered in cases of post-COVID-19 symptoms of severe diarrhea due to a possible abnormal immune response related to COVID-19.

Differences in COVID-19 treatment across Japan: Analysis of the COVID-19 Registry Japan (COVIREGI-JP)

BACKGROUND

This study investigated the differences between metropolitan and non-metropolitan areas in the treatment of hospitalized patients with COVID-19 using data from the nationwide COVID-19 Registry Japan (COVIREGI-JP).

METHODS

Data of patients hospitalized for COVID-19 during waves 2-4 (June 1, 2020-June 30, 2021) treated in one of the 800 medical institutions participating in the Registry were extracted. Treatment and treatment outcomes were evaluated in inpatients with moderate 2 and severe disease using propensity score matching performed between metropolitan and non-metropolitan areas.

RESULTS

A total of 32797 patients were identified during epidemic waves 2-4. After matching (wave 2, n = 307; wave 3, n = 913; wave 4, n = 479), the population comprised mostly elderly patients with a median age of ≥65 years (IQR: 52-81 years) and median SpO2 of 93/94 (IQR: 91%-96%), and the proportion of patients with moderate 2 (SpO2≤93%/require oxygenation) vs severe disease (ICU admission) ranged from 82.7% to 89.8% vs 10.2% to 17.3% in metropolitan areas vs non-metropolitan areas, respectively, across all epidemic waves. Noninvasive mechanical ventilation was used significantly more in waves 2 and 3 and invasive mechanical ventilation in wave 4 in metropolitan vs non-metropolitan areas, compared with other waves. In wave 2, death as an outcome was significantly higher in metropolitan vs non-metropolitan areas compared with patient discharge to home/transfer.

CONCLUSION

During the COVID-19 epidemic, starting from wave 2 up until and through wave 4, no clear differences in mortality rates and no regional differences in treatment provision patterns were observed between metropolitan and non-metropolitan areas in Japan.

Comparative effectiveness of tocilizumab vs standard care in patients with severe COVID-19-related pneumonia: a retrospective cohort study utilizing registry data as a synthetic control

BACKGROUND

The severity of coronavirus disease 2019 (COVID-19) infections has led to the development of several therapeutic agents, with tocilizumab becoming increasingly used to treat patients with COVID-19-related pneumonia. This study compared the use of tocilizumab treatment with the standard of care (SOC) to determine its efficacy against severe COVID-19-related pneumonia in Japan.

METHODS

This retrospective cohort study was designed to evaluate the efficacy of tocilizumab in two different databases: the JA42434 single-arm study and COVID-19 Registry Japan (COVIREGI-JP), with a synthetic control group from the COVIREGI-JP cohort as a benchmark for the tocilizumab group. The study's primary objective was to evaluate the efficacy of tocilizumab in treating severe COVID-19-related pneumonia compared to the SOC among patients included in the above two databases. The SOC group was extracted as the synthetic control group using exact matching and a propensity score matching in sequence per subject. As a secondary objective, the efficacy of tocilizumab compared to the SOC was evaluated exclusively among patients included in the COVIREGI-JP database. In each objective, the primary endpoint was defined as the time to discharge or the status of awaiting discharge.

RESULTS

For the primary endpoint, the hazard ratio (HR) of the tocilizumab group against the SOC group was 1.070 (95% confidence interval [CI]: 0.565-2.028). The median time from Study Day 1 to discharge or the state of awaiting discharge was 15 days in the tocilizumab group and 16 days in the SOC group. The HRs for the secondary endpoints, namely, time to improvement in the clinical state, time to clinical failure, and time to recovery, were 1.112 (95% CI: 0.596-2.075), 0.628 (95% CI: 0.202-1.953), and 1.019 (95% CI: 0.555-1.871), respectively. Similarly, the HR of the primary endpoint for the secondary objective was 0.846 (95% CI: 0.582-1.230).

CONCLUSIONS

Tocilizumab did not demonstrate a positive effect on time to discharge or the state of awaiting discharge. Furthermore, no statistically significant differences in other clinical outcomes, such as time to improvement in the clinical state, time to clinical failure, and time to recovery, were observed among the groups.

Obesity, overweight, and severe prognosis in COVID-19 patients in Japan

INTRODUCTION

Obesity (i.e., body mass index [BMI] of 30 kg/m2 or more) is one of the risk factors for severe COVID-19, but the findings may not be directly applicable to Asians, who have a different cutoff point for defining obesity. We thus examined the association between obesity/overweight (BMI of 25 kg/m2 or more and less than 30 kg/m2) and the risk of COVID-19 severity.

METHODS

The study population included COVID-19 patients who had been enrolled in the registry of the Okayama City Public Health Center in Okayama, Japan, between March 2020 and June 2022. We included 27 820 patients who had information on BMI and prognosis, and we conducted Poisson regression analysis with robust error variance to estimate risk ratios (RRs) with 95% confidence intervals (CIs) for severe outcomes.

RESULTS

Obesity and overweight were associated with the increased risk of severe COVID-19 in all age categories. The RRs (95% CI) for COVID-19 induced respiratory failure compared to the normal weight category were 1.57 (1.31-1.88) for overweight and 2.45 (1.90-3.15) for obesity.

CONCLUSIONS

Both obesity and overweight were associated with increased risk of severe COVID-19. This study suggests the importance of the overweight category to predict the risk of severe COVID-19 in Asians.

Risk factors of early mortality in COVID-19 patients in Indonesia: A retrospective cohort study in a provincial referral hospital of Aceh

Some of coronavirus disease 2019 (COVID-19) patients died after being hospitalized and early mortality is a matter of concern during the pandemic; therefore, it is critical to determine which patients are the most vulnerable of having early mortality. The aim of this study was to determine the risk factors for early mortality among hospitalized COVID-19 patients in Indonesia. A retrospective cohort study was conducted on hospitalized COVID-19 patients from July 2020 to September 2021 at Dr. Zainoel Abidin Hospital, Banda Aceh, Indonesia. Demographic data, clinical characteristics, laboratory findings, and mortality were collected. Early mortality was defined as a death before seven days of the hospitalization. Multivariate regression analysis was employed to determine the risk factors associated with early mortality. We included the data of 624 COVID-19 patients who died during the study period. More than half of the patients were male and aged over 50 years old. The average hospitalization period was 10 days and most patients had more than two comorbidities. Chronic lung disease was the most common comorbidity (46.0%) followed by respiratory disease (26.8%) and heart disease (14.3%). Multiple comorbidities and elevated D-dimers exceeding 3376.92 ng/mL were associated with early mortality with OR: 7.029; 95%CI: 2.02-24.43 and OR: 1.000085, 95%CI: 1.000028-1.000142, respectively. In conclusion, early mortality in COVID-19 patients was associated with having multiple comorbidities and elevated D-dimer level. Therefore, it is crucial to assess the presence of comorbidities and routine laboratory test while managing COVID-19 patients in order to prevent the early mortality.

Prediction of oxygen supplementation by a deep-learning model integrating clinical parameters and chest CT images in COVID-19

PURPOSE

As of March 2023, the number of patients with COVID-19 worldwide is declining, but the early diagnosis of patients requiring inpatient treatment and the appropriate allocation of limited healthcare resources remain unresolved issues. In this study we constructed a deep-learning (DL) model to predict the need for oxygen supplementation using clinical information and chest CT images of patients with COVID-19.

MATERIALS AND METHODS

We retrospectively enrolled 738 patients with COVID-19 for whom clinical information (patient background, clinical symptoms, and blood test findings) was available and chest CT imaging was performed. The initial data set was divided into 591 training and 147 evaluation data. We developed a DL model that predicted oxygen supplementation by integrating clinical information and CT images. The model was validated at two other facilities (n = 191 and n = 230). In addition, the importance of clinical information for prediction was assessed.

RESULTS

The proposed DL model showed an area under the curve (AUC) of 89.9% for predicting oxygen supplementation. Validation from the two other facilities showed an AUC > 80%. With respect to interpretation of the model, the contribution of dyspnea and the lactate dehydrogenase level was higher in the model.

CONCLUSIONS

The DL model integrating clinical information and chest CT images had high predictive accuracy. DL-based prediction of disease severity might be helpful in the clinical management of patients with COVID-19.

Comprehensive analysis of long COVID in a Japanese nationwide prospective cohort study

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly since 2019, and the number of reports regarding long COVID has increased. Although the distribution of long COVID depends on patient characteristics, epidemiological data on Japanese patients are limited. Hence, this study aimed to investigate the distribution of long COVID in Japanese patients. This study is the first nationwide Japanese prospective cohort study on long COVID.

METHODS

This multicenter, prospective cohort study enrolled hospitalized COVID-19 patients aged ≥18 years at 26 Japanese medical institutions. In total, 1200 patients were enrolled. Clinical information and patient-reported outcomes were collected from medical records, paper questionnaires, and smartphone applications.

RESULTS

We collected data from 1066 cases with both medical records and patient-reported outcomes. The proportion of patients with at least one symptom decreased chronologically from 93.9% (947/1009) during hospitalization to 46.3% (433/935), 40.5% (350/865), and 33.0% (239/724) at 3, 6, and 12 months, respectively. Patients with at least one long COVID symptom showed lower quality of life and scored higher on assessments for depression, anxiety, and fear of COVID-19. Female sex, middle age (41-64 years), oxygen requirement, and critical condition during hospitalization were risk factors for long COVID.

CONCLUSIONS

This study elucidated the symptom distribution and risks of long COVID in the Japanese population. This study provides reference data for future studies of long COVID in Japan.

Quantitative analysis of chest computed tomography of COVID-19 pneumonia using a software widely used in Japan

This study aimed to determine the optimal conditions to measure the percentage of the area considered as pneumonia (pneumonia volume ratio [PVR]) and the computed tomography (CT) score due to coronavirus disease 2019 (COVID-19) using the Ziostation2 image analysis software (Z2; Ziosoft, Tokyo, Japan), which is popular in Japan, and to evaluate its usefulness for assessing the clinical severity. We included 53 patients (41 men and 12 women, mean age: 61.3 years) diagnosed with COVID-19 using polymerase chain reaction who had undergone chest CT and were hospitalized between January 2020 and January 2021. Based on the COVID-19 infection severity, the patients were classified as mild (n = 38) or severe (n = 15). For 10 randomly selected samples, the PVR and CT scores by Z2 under different conditions and the visual simple PVR and CT scores were compared. The conditions with the highest statistical agreement were determined. The usefulness of the clinical severity assessment based on the PVR and CT scores using Z2 under the determined conditions was statistically evaluated. The best agreement with the visual measurement was achieved by the Z2 measurement condition of ≥-600 HU. The areas under the receiver operating characteristic curves, Youden's index, and the sensitivity, specificity, and p-values of the PVR and CT scores by Z2 were as follows: PVR: 0.881, 18.69, 66.7, 94.7, and <0.001; CT score: 0.77, 7.5, 40, 74, and 0.002, respectively. We determined the optimal condition for assessing the PVR of COVID-19 pneumonia using Z2 and demonstrated that the AUC of the PVR was higher than that of CT scores in the assessment of clinical severity. The introduction of new technologies is time-consuming and expensive; our method has high clinical utility and can be promptly used in any facility where Z2 has been introduced.

Efficacy of Early Rehabilitation for Severe Coronavirus Disease 2019 Pneumonia: Factor Analysis Using Machine Learning

Objectives

Patients with severe coronavirus disease 2019 (COVID-19) who develop pneumonia face the risk of ventilatory muscle disuse in the acute phase, which can result in persistent respiratory impairments in the subacute phase. Although rehabilitation during the acute phase is considered effective, there are limited reports on this topic. Therefore, this study aimed to investigate the effectiveness of acute-phase rehabilitation in patients with severe COVID-19.

Methods

The study included 57 patients (45 men and 12 women; mean age: 63.2±12.1 years) admitted between April and June 2021, all of whom required intubation for respiratory management. Among them, 34 patients underwent acute-phase rehabilitation interventions based on the early goal-directed mobilization protocol. The primary objectives were to assess the occurrence of medical accidents related to acute-phase rehabilitation and evaluate their impact on survival and mobility upon hospital discharge. Statistical techniques and machine learning algorithms were employed for data analysis.

Results

Remarkably, no medical accidents occurred during the acute-phase rehabilitation among the patients. Furthermore, our findings indicated that acute-phase rehabilitation did not influence survival outcomes. However, it did have a positive impact on the mobility of patients upon hospital discharge.

Conclusions

Acute-phase rehabilitation can be safely administered to patients with severe COVID-19 by following an early goal-directed mobilization protocol. This approach may also contribute to improved activities of daily living after discharge.

Risk Factors Associated with Mortality among Mechanically Ventilated Patients with Coronavirus Disease 2019 Pneumonia: A Multicenter Cohort Study in Japan (J-RECOVER Study)

Objective Mortality analyses of patients with coronavirus disease 2019 (COVID-19) requiring invasive mechanical ventilation in Japan are limited. The present study therefore determined the risk factors for mortality in patients with COVID-19 requiring invasive mechanical ventilation. Methods This retrospective cohort study used the dataset from the Japanese multicenter research of COVID-19 by assembling real-word data (J-RECOVER) study that was conducted between January 1 and September 31, 2020. Independent risk factors associated with in-hospital mortality were evaluated using a multivariate logistic regression analysis. Kaplan-Meier estimates of the survival were calculated for different age groups. A subgroup analysis was performed to assess differences in survival rates according to additional risk factors, including an older age and chronic pulmonary disease. Patients A total of 561 patients were eligible. The median age was 67 (interquartile range: 56-75) years old, 442 (78.8%) were men, and 151 (26.9%) died in the hospital. Results Age, chronic pulmonary disease, and renal disease were significantly associated with in-hospital mortality. Compared with patients 18-54 years old, the adjusted odds ratios of patients 55-64, 65-74, and 75-94 years old were 3.34 (95% CI, 1.34-8.31), 7.07 (95% CI, 3.05-16.40), and 18.43 (95% CI, 7.94-42.78), respectively. Conclusion Age, chronic pulmonary disease, and renal disease were independently associated with mortality in patients with COVID-19 requiring invasive mechanical ventilation, and age was the most decisive indicator of a poor prognosis. Our results may aid in formulating treatment strategies and allocating healthcare resources.

Clinical Features Comparing Arterial Thrombosis and Venous Thromboembolism in Hospitalized Patients with COVID-19: Result from the CLOT-COVID Study

Objectives: This study aimed to investigate the clinical features of arterial thrombosis and venous thromboembolism (VTE) in coronavirus disease 2019 (COVID-19). Methods: The CLOT-COVID Study was a retrospective, multicenter cohort study that enrolled 2,894 consecutively hospitalized patients with COVID-19 among 16 centers in Japan from April 2021 to September 2021. We compared the clinical features of arterial thrombosis and VTE. Results: Thrombosis was observed in 55 patients (1.9%) during hospitalization. Arterial thrombosis and VTE occurred in 12 (0.4%) and 36 (1.2%) patients, respectively. Among the 12 patients with arterial thrombosis, 9 (75%), 2 (17%), and 1 developed ischemic cerebral infarction, myocardial infarction, and acute limb ischemia, respectively, and there were five patients (42%) without comorbidities. Among 36 patients with VTE, 19 (53%) and 17 (47%) developed pulmonary embolism (PE) and deep vein thrombosis (DVT), respectively. PE was common in the early stages of hospitalization; whereas, DVT was common beyond the early stages of hospitalization. Conclusion: Among patients with COVID-19, arterial thrombosis was less common than VTE, although ischemic cerebral infarction seemed to be relatively common, and a certain number of patients developed arterial thrombosis even in the absence of known atherosclerosis risk factors.

Epidemiological study of vaccination against SARS-CoV-2 and its impact on COVID-19 progression in a cohort of patients in gran Canaria

Objectives. We analyzed the impact of age, sex, vaccination against COVID-19, immunosuppressive treatment, and comorbidities on patients' risk of requiring hospital admission or of death. Methods. Population-based observational retrospective study conducted on a cohort of 19,850 patients aged 12 years or more, who were diagnosed with COVID-19 between June 1st and December 31st, 2021, in the island of Gran Canaria. Results. Hypertension (18.5%), asthma (12.8%) and diabetes (7.2%) were the most frequent comorbidities; 147 patients died (0.7%). The combination of advanced age, male sex, cancer, coronary heart disease, immunosuppressive treatment, hospital admission, admission to the intensive care unit, mechanical ventilation and lack of complete COVID-19 vaccination or booster dose was strongly predictive of mortality (p < 0.05); 831 patients required hospital admission and it was more frequent in men, older age groups, and patients with cancer, diabetes, arterial hypertension, chronic obstructive pulmonary disease, congestive heart failure or immunosuppressive treatment. The COVID-19 vaccine booster dose was associated with a lower risk of death ([OR] 0.11, 95% CI 0.06-0.21, p < 0.05) or hospital admission ([OR] 0.36, 95% CI 0.29-0.46, p < 0.05). Conclusions. Cancer, coronary heart disease, and immunosuppressive treatment were associated with increased COVID-19 mortality. More complete vaccination was associated with lower risk of hospital admission or death. Three doses of the SARS-CoV-2 vaccine were highly associated with the prevention of death and hospital admission in all age groups. These findings suggest that COVID-19 vaccination can help bring the pandemic under control.

Clinical efficacy of remdesivir for COVID-19 in children: A propensity-score-matched analysis

Clinical efficacy of remdesivir in children with COVID-19 is unclear. This propensity-score-matched retrospective cohort study of children with COVID-19 showed that the rate of patients achieving defervescence on Day 4 was higher in the remdesivir group than in the non-remdesivir group, but was not statistically different (86.7% vs 73.3%, P = 0.333).

The Japanese Guide affected the prescription of steroids for COVID-19 inpatients during the COVID-19 epidemic in Japan

Since the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, guidance ("Japanese Guide") has been published by a working group of several academic societies and announced by the Ministry of Health, Labour, and Welfare. Steroids as a candidate treatment for COVID-19 were noted in the Japanese Guide. However, the prescription details for steroids, and whether the Japanese Guide changed its clinical practice, were unclear. This study aimed to examine the impact of the Japanese Guide on the trends in the prescription of steroids for COVID-19 inpatients in Japan. We selected our study population using Diagnostic Procedure Combination (DPC) data from hospitals participating in the Quality Indicator/Improvement Project (QIP). The inclusion criteria were patients discharged from hospital between January 2020 and December 2020, who had been diagnosed with COVID-19, and were aged 18 years or older. The epidemiological characteristics of cases and the proportion of steroid prescriptions were described on a weekly basis. The same analysis was performed for subgroups classified by disease severity. The study population comprised 8603 cases (410 severe cases, 2231 moderate II cases, and 5962 moderate I/mild cases). The maximum proportion of cases prescribed with dexamethasone increased remarkably from 2.5 to 35.2% in the study population before and after week 29 (July 2020), when dexamethasone was included in the guidance. These increases were 7.7% to 58.7% in severe cases, 5.0% to 57.2% in moderate II cases, and 1.1% to 19.2% in moderate I/mild cases. Although the proportion of cases prescribed prednisolone and methylprednisolone decreased in moderate II and moderate I/mild cases, it remained high in severe cases. We showed the trends of steroid prescriptions in COVID-19 inpatients. The results showed that guidance can influence drug treatment provided during an emerging infectious disease pandemic.

Coinfection with SARS-CoV-2 and Cytomegalovirus in a Patient with Mild COVID-19

Persistent fever due to coronavirus disease 2019 (COVID-19) is a considerable issue for patients and physicians that requires a broad differential diagnosis and evaluation of complications. Coinfections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and various respiratory viruses have also been reported. In severe cases of COVID-19, cytomegalovirus (CMV) reactivation or CMV coinfection with SARS-CoV-2 has been reported in association with critical illnesses and immunosuppressive therapy; however, in mild COVID-19 cases, CMV coinfection with SARS-CoV-2 has been reported only in severely immunocompromised patients, and its incidence and clinical importance remain unclear. Herein, we report a rare case of coinfection with SARS-CoV-2 and CMV in a patient with mild COVID-19 and untreated diabetes mellitus, which led to persistent fever for approximately 4 weeks. CMV coinfection should be considered in patients with COVID-19 who exhibit persistent fever.

Clinical Characteristics and Serum Cytokines Profiling in Hospitalized COVID-19 Patients in Lebanon

Since its emergence, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a public health threat worldwide. While the majority of patients recover in 3-4 weeks, complications in severely ill patients, including acute respiratory distress syndrome, cardiac injury, thrombosis, and sepsis, can lead to death. Several biomarkers, in addition to cytokine release syndrome (CRS), have been associated with severe and fatal outcomes in coronavirus disease 2019 (COVID-19) patients. The aim of this study is to assess clinical characteristics and cytokines profiles in hospitalized COVID-19 patients in Lebanon. A total of 51 hospitalized COVID-19 patients were recruited between February 2021 and May 2022. Clinical data and sera were collected at two time points: at hospital presentation (T0) and last collected results during hospitalization (T1). Our results showed that 49% of participants were >60 years with males accounting for the majority (72.5%). Hypertension, followed by diabetes and dyslipidemia, were the most frequent comorbid conditions among study participants accounting for 56.9% and 31.4%, respectively. Chronic obstructive pulmonary disease (COPD) was the only significantly different comorbid condition between intensive care unit (ICU) and non-ICU patients. Our results also showed that the median level of D-dimer was significantly elevated among patients in ICU and those who died compared to non-ICU patients and those who survived. Moreover, C-reactive protein (CRP) levels were significantly higher at T0 compared to T1 in ICU and non-ICU patients. The median level of IL-12p70 was significantly higher in patients >60 years compared to those ≤60 years (p = 0.0209). Our data are in agreement with previous reports suggesting the importance of IL-6, CRP, and IL-12p70 in the assessment of risk of severe disease and mortality.

Determinant Factors of Mortality in Pre-elderly and Elderly Patients With COVID-19 in Jakarta, Indonesia

OBJECTIVES

This study aimed to identify risk factors associated with coronavirus disease 2019 (COVID-19) mortality in pre-elderly and elderly individuals in Jakarta, Indonesia.

METHODS

We employed a case-control study design, utilizing secondary data from the Epidemiology Surveillance, Immunization Prevention, and Disease Control Sections of the DKI Jakarta Provincial Health Office, collected from December 2020 to January 2021. The study included 188 cases and an equal number of controls. Cases were COVID-19 patients confirmed to have died, as reported by hospitals and communities and subsequently verified by healthcare workers. Control subjects were patients who completed a 14-day isolation period and had been officially declared recovered by healthcare professionals. The dependent variable was the mortality of COVID-19 patients in the January 2021 period. The independent variables consisted of demographic data (age and sex), clinical symptoms (cough, runny nose, anosmia, diarrhea, headaches, abdominal pain, muscle pain, and nausea/vomiting), and comorbidities (hypertension, heart disease, and diabetes). Multivariate analysis was conducted using multiple logistic regression.

RESULTS

The multiple logistic regression analysis revealed several factors associated with COVID-19 fatalities in Jakarta: age of 60 years or older (odds ratio [OR], 4.84; 95% CI, 3.00 to 7.80), male (OR, 2.38; 95% CI, 2.41 to 3.68), dyspnea (OR, 3.93; 95% CI, 2.04 to 7.55), anosmia (OR, 0.13; 95% CI, 0.04 to 0.46), and heart disease (OR, 4.38; 95% CI, 1.04 to 18.46).

CONCLUSIONS

The control and prevention of COVID-19 among elderly individuals require particular vigilance. When a COVID-19 case is detected within this demographic, prompt treatment and medication administration are crucial to mitigate the presenting symptoms.

Clinical trial experience in Japan and future issues in developing drugs to treat COVID-19

The National Center for Global Health and Medicine plays a central role in the treatment and research of infectious diseases in Japan. It has conducted various research and development activities on drugs to treat coronavirus disease 2019 (COVID-19) with clinical questions as starting points. Clinical trials are essential in developing new treatment modalities, but we have noticed some characteristic difficulties in clinical trials on emerging and re-emerging infectious diseases. For example, since there is no standard of care when an emerging infectious disease starts to spread, establishing an appropriate control group is complicated, and many things are hurried at the start of trials. This means there is little time to arrange a placebo, and conducting blinded, randomized, controlled trials has been difficult. Another issue characteristic of infectious disease has been that progress in enrolling subjects is affected by the spread of the disease. It was also a struggle to select institutions that provide medical care on the front lines of infectious disease and conduct clinical trials regularly. To start multicenter clinical trials expeditiously, a regulated and structured network is thus considered necessary. From the perspective of implementation, it is preferable to conduct decentralized clinical trials (DCTs) that do not depend on people coming to the medical institution, while from the perspective of preventing infections during the spread of COVID-19, wide adoption of eConsent is desirable. Based on the experience of COVID-19, new measures must be taken to prepare for emerging and re-emerging infectious diseases in the future.

Thrombotic Mechanism Involving Platelet Activation, Hypercoagulability and Hypofibrinolysis in Coronavirus Disease 2019

Coronavirus disease 2019 (COVID-19) has spread, with thrombotic complications being increasingly frequently reported. Although thrombosis is frequently complicated in septic patients, there are some differences in the thrombosis noted with COVID-19 and that noted with bacterial infections. The incidence (6-26%) of thrombosis varied among reports in patients with COVID-19; the incidences of venous thromboembolism and acute arterial thrombosis were 4.8-21.0% and 0.7-3.7%, respectively. Although disseminated intravascular coagulation (DIC) is frequently associated with bacterial infections, a few cases of DIC have been reported in association with COVID-19. Fibrin-related markers, such as D-dimer levels, are extremely high in bacterial infections, whereas soluble C-type lectin-like receptor 2 (sCLEC-2) levels are high in COVID-19, suggesting that hypercoagulable and hyperfibrinolytic states are predominant in bacterial infections, whereas hypercoagulable and hypofibrinolytic states with platelet activation are predominant in COVID-19. Marked platelet activation, hypercoagulability and hypofibrinolytic states may cause thrombosis in patients with COVID-19.

Association of acute-to-chronic glycemic ratio and outcomes in patients with COVID-19 and undiagnosed diabetes mellitus: A retrospective nationwide cohort study

AIMS/INTRODUCTION

To assess the association of undiagnosed diabetes mellitus and its acute-to-chronic glycemic ratio with clinical outcome in patients hospitalized with coronavirus disease 2019 (COVID-19) using a large-scale nationwide registry in Japan.

MATERIALS AND METHODS

Overall, 4,747 patients were included between July 2021 and January 2022. We evaluated blood glucose and glycated hemoglobin levels at admission, and calculated the acute-to-chronic glycemic ratio for each non-diabetes mellitus, undiagnosed diabetes mellitus and pre-existing diabetes mellitus group. The primary composite outcome comprised in-hospital mortality, invasive mechanical ventilation, extracorporeal membrane oxygenation support, intensive care unit admission and transfer to a more advanced medical facility.

RESULTS

Compared with the non-diabetes mellitus group, the undiagnosed diabetes mellitus group was significantly associated with a worse COVID-19 outcome (odds ratio 2.18, 95% confidence interval 1.50-3.18). In patients with undiagnosed diabetes mellitus, the 3rd tertile of the acute-to-chronic glycemic ratio was linked with a worse COVID-19 outcome compared with the 1st tertile (odds ratio 3.33, 95% confidence interval 1.43-7.77), whereas glycated hemoglobin levels were not; among patients with pre-existing diabetes mellitus, glycated hemoglobin levels were linked with a worse outcome.

CONCLUSIONS

Among patients with undiagnosed diabetes mellitus with COVID-19, the magnitude of elevation of blood glucose from chronic to acute levels is associated with worse outcomes.

Mortality-associated Risk Factors in Hospitalized COVID-19 Patients in Japan: Findings of the CLOT-COVID Study

BACKGROUND

Reports of mortality-associated risk factors in patients with the novel coronavirus disease 2019 (COVID-19) are limited.

METHODS

We evaluated the clinical features that were associated with mortality among patients who died during hospitalization (n = 158) and those who were alive at discharge (n = 2,736) from the large-scale, multicenter, retrospective, observational cohort CLOT-COVID study, which enrolled consecutively hospitalized COVID-19 patients from 16 centers in Japan from April to September 2021. Data from 2,894 hospitalized COVID-19 participants of the CLOT-COVID study were analyzed in this study.

RESULTS

Patients who died were older (71.1 years vs 51.6 years, P < 0.001), had higher median D-dimer values on admission (1.7 µg/mL vs 0.8 µg/mL, P < 0.001), and had more comorbidities. On admission, the patients who died had more severe COVID-19 than did those who survived (mild: 16% vs 63%, moderate: 47% vs 31%, and severe: 37% vs 6.2%, P < 0.001). In patients who died, the incidence of thrombosis and major bleeding during hospitalization was significantly higher than that in those who survived (thrombosis: 8.2% vs 1.5%, P < 0.001; major bleeding: 12.7% vs 1.4%, P < 0.001). Multivariable logistic regression analysis revealed that age >70 years, high D-dimer values on admission, heart disease, active cancer, higher COVID-19 severity on admission, and development of major bleeding during hospitalization were independently associated with a higher mortality risk.

CONCLUSION

This large-scale observational study in Japan identified several independent risk factors for mortality in hospitalized patients with COVID-19 that could facilitate appropriate risk stratification of patients with COVID-19.

Serum Lactate Dehydrogenase Level One Week after Admission Is the Strongest Predictor of Prognosis of COVID-19: A Large Observational Study Using the COVID-19 Registry Japan

Clinical features of COVID-19 are diverse, and a useful tool for predicting clinical outcomes based on clinical characteristics of COVID-19 is needed. This study examined the laboratory values and trends that influence mortality in hospitalised COVID-19 patients. Data on hospitalised patients enrolled in a registry study in Japan (COVID-19 Registry Japan) were obtained. Patients with records on basic information, outcomes, and laboratory data on the day of admission (day 1) and day 8 were included. In-hospital mortality was set as the outcome, and associated factors were identified by multivariate analysis using the stepwise method. A total of 8860 hospitalised patients were included. The group with lactate dehydrogenase (LDH) levels >222 IU/L on day 8 had a higher mortality rate compared to the group with LDH levels ≤222 IU/L. Similar results were observed in subgroups formed by age, body mass index (BMI), underlying disease, and mutation type, except for those aged <50 years. When age, sex, BMI, underlying disease, and laboratory values on days 1 and 8 were tested for factors strongly associated with in-hospital mortality, LDH on day 8 was most strongly associated with mortality. LDH level on day 8 was the strongest predictor of in-hospital mortality in hospitalised COVID-19 patients, indicating its potential usefulness in post-treatment decision-making in severe COVID-19 cases.

Comparison of the clinical characteristics and outcomes of Japanese patients with COVID-19 treated in primary, secondary, and tertiary care facilities

AIM

To compare the characteristics and clinical course of patients with coronavirus disease (COVID-19) according to the healthcare level of the admitted hospital, to provide an insight into determining the appropriate level of care for each patient.

METHODS

This retrospective, observational study utilized data from the COVID-19 Registry Japan (COVIREGI-JP), the largest Japanese registry of hospitalized patients with COVID-19. Datasets were obtained from reports filed as of May 31, 2022.

RESULTS

A total of 59,707 patients (2004 in the primary care group, 41,420 in the secondary care group, and 16,283 in the tertiary care group) from 585 facilities were included in the analysis. Patients with established risk factors for severe disease, such as old age and the presence of comorbidities, were treated at higher care facilities and had poorer initial conditions and in-hospital clinical course, as well as higher mortality. Analysis of the fatality rates for each complication suggested that patients with complications requiring procedures (e.g. pleural effusions, myocardial ischemia, and arrhythmia) may have better survival rates in facilities with specialist availability. The number of deaths and severe COVID-19 cases in this study were notably less than those reported overseas.

CONCLUSION

Our results showed that more difficult COVID-19 cases with poor outcomes were treated at higher care level facilities in Japan. Attending to possible complications may be useful for selecting an appropriate treatment hospital. Healthcare providers need to maintain a broad perspective on the distribution of medical resources.

Impact of COVID-19 on the Surrounding Environment of Nursing Home Residents and Attitudes towards Infection Control and Oral Health Care among Nursing Home Staff in Japan

The environments of nursing home staff and residents have dramatically changed since the onset of the COVID-19 pandemic, with greater demand for infection control. This study aimed to clarify the changes and regional differences in the surrounding environment of nursing home residents as well as the working environment of staff, including oral health care, after the spread of SARS-CoV-2. A self-administered questionnaire survey was sent to nursing staff at about 40 nursing homes in different areas of Japan in September and October 2021. The questionnaire consisted of items centered around: (1) the surrounding environment of nursing home residents, (2) awareness and attitudes towards daily work among staff, and (3) attitudes to and procedures for oral health care among staff. A total of 929 respondents included 618 (66.5%) nursing care workers and 134 (14.4%) nurses. Regarding changes in resident daily life, 60% of staff perceived decreases in psychosocial and physical function after the start of the pandemic due to limited family communication and recreational activities, especially in urban areas. Concerning infection control, most respondents adopted routines of disinfecting hands before and after their duties. Oral health care was part of the regular duties of over 80% of respondents. Many participants answered that the frequency and time of oral health care only slightly changed after the onset of COVID-19, but many also reported disinfecting hands both before and after oral health care, particularly in rural areas. Our findings suggested that the COVID-19 pandemic decreased the daily living activities of residents, leading to psychosocial and physical decline, especially in urban areas. The results also indicated that the spread of SARS-CoV-2 triggered improvements in the awareness and attitudes towards infection control in daily work, including oral health care, among nursing care staff, notably in rural areas. Such an effect may contribute to a more positive perception of oral health care infection measures after the pandemic.

Impact of accumulative smoking exposure and chronic obstructive pulmonary disease on COVID-19 outcomes: report based on findings from the Japan COVID-19 task force

OBJECTIVES

Smoking and chronic obstructive pulmonary disease (COPD) are risk factors for severe COVID-19. However, limited literature exists on the effect of COPD and smoking on COVID-19 outcomes. This study examined the impact of smoking exposure in pack-years (PY) and COPD on COVID-19 outcomes among smokers in Japan.

METHODS

The study included 1266 smokers enrolled by the Japan COVID-19 task force between February 2020 and December 2021. PY and COPD status was self-reported by patients. Patients were classified into the non-COPD (n = 1151) and COPD (n = 115) groups; the non-COPD group was further classified into <10 PY (n = 293), 10-30 PY (n = 497), and >30 PY (n = 361). The study outcome was the need for invasive mechanical ventilation (IMV).

RESULTS

The incidence of IMV increased with increasing PY and was highest in the COPD group (<10 PY = 7.8%, 10-30 PY = 12.3%, >30 PY = 15.2%, COPD = 26.1%; P <0.001). A significant association was found for IMV requirement in the >30 PY and COPD groups through univariate (odds ratio [OR]: >30 PY = 2.11, COPD = 4.14) and multivariate (OR: >30 PY = 2.38; COPD = 7.94) analyses. Increasing PY number was also associated with increased IMV requirement in patients aged <65 years.

CONCLUSION

Cumulative smoking exposure was positively associated with COVID-19 outcomes in smokers.

COVID-19 pandemic and hypertension: an updated report from the Japanese Society of Hypertension project team on COVID-19

The number of reported cases with coronavirus disease 2019 (COVID-19) has exceeded 620 million worldwide, still having a profound impact on people's health and daily lives since its occurrence and outbreak in December 2019. From the early phase of the COVID-19 pandemic, there has been a concern that the rapid spread of this communicable disease can negatively influence non-communicable diseases. Accumulating data indicate that the restriction on the access to medical care, psychological distress, and life-style changes triggered by the pandemic have indeed affected blood pressure control in hypertensive patients. Since our previous report in 2020 that summarized the findings of the literature related to COVID-19 and hypertension, there has been a considerable progress in our understanding of the association between these two disorders; nonetheless, there are remaining challenges and emerging questions in the field. In this article, we aim to summarize the latest information on the impact of the pandemic on blood pressure control, the use of the renin-angiotensin system inhibitors in patients with COVID-19, and the blood pressure changes as one of the possible post-acute sequelae of COVID-19 (also known as long COVID). We also summarize the evidence of telemedicine and COVID-19 vaccination in hypertensive subjects, based on data available as of June 2022.

Urinary L-Type Fatty Acid-Binding Protein Predicts Oxygen Demand of COVID-19 in Initially Mild Cases

Early detection of illness trajectory in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected patients is crucial for patients and healthcare workers. An effective, noninvasive approach, with simple measurement for decision-making, is necessary in a pandemic to discriminate between high- and low-risk patients, even though both groups may exhibit mild symptoms in the beginning.

OBJECTIVES

To predict COVID-19 disease severity within 10 days, distinguishing cases that will progress to moderate or severe versus mild, patient urinary L-type fatty acid-binding protein (L-FABP) was assayed within 4 days of receiving a diagnosis. The study also examined whether L-FABP point of care (POC) test is helpful in risk screening.

DESIGN

Symptomatic subjects who tested positive for SARS-CoV-2 and were hospitalized were prospectively enrolled at the National Center for Global Health and Medicine (NCGM), Yamanashi Prefectural Central Hospital (YPCH), and Sinai Hospital in Maryland. The outcome of each case was evaluated 7 days after admission and the diagnostic performance of L-FABP was assessed.

SETTING AND PARTICIPANTS

Subjects were treated for COVID-19 at public healthcare centers in Japan from January 31, 2020, to January 31, 2021, to NCGM, YPCH, and at Sinai Hospital in Baltimore, MD, during the same period.

MAIN OUTCOMES AND MEASURES

The primary outcome was to determine whether urinary L-FABP within 48 hours of admission can predict the patient's severity of COVID-19 1 week later. We obtained demographic data, information on clinical symptoms, radiographic images, and laboratory data.

RESULTS

Diagnostic performance was assessed using receiver operating characteristic analysis. Of the 224 participants in the study, 173 initially had a mild form of COVID-19. The area under the curve (AUC) for a severe outcome was 93.5%. L-FABP POC risk prediction of a severe outcome had an AUC of 88.9%.

CONCLUSIONS AND RELEVANCE

Urinary L-FABP can predict patient risk of COVID-19 illness severity. L-FABP POC is implementable for patient management. (ClinicalTrials.gov number, NCT04681040).

Concurrent lung adenocarcinoma hidden among multiple shadows of COVID-19 pneumonia: A rare and instructive case report

A 40-year-old man was admitted with a diagnosis of COVID-19 pneumonia. Although most of multiple ground-glass opacities and consolidations on computed tomography improved, a round ground-glass opacity with consolidation remained unchanged and was suspected to be a part-solid nodule of lung adenocarcinoma. Pathologic diagnosis of resected tumor was papillary adenocarcinoma.

Regional trends in the use of steroids and favipiravir for COVID-19 treatment

BACKGROUND

Infectious diseases are treated based on clinical guidelines, which usually require a large amount of data and time to formulate. Therefore, various treatments are tried and used in the early stages of epidemics of emerging and reemerging infectious diseases. In this study, we focused on two drugs for coronavirus disease 2019 (COVID-19) treatment, i.e., steroids and favipiravir, and analyzed the changes in treatment trends by region.

METHODS

This was a retrospective study of cases from the COVID-19 Registry Japan. The proportion of patients who received steroids and favipiravir was calculated on a monthly and pandemic wave basis, and the trend of drug administration by region was estimated using logistic curves.

RESULTS

The effect of wave on steroid administration was as high as 2.75 [2.60, 2.90], indicating a rapid increase in the proportion of steroid administration. The odds ratios for Hokuriku and Hokkaido were 0.49 [0.35, 0.68] and 0.55 [0.43, 0.71], respectively, indicating that steroids were less likely administered in these regions. For favipiravir, the effect of timing was 0.43 [0.41, 0.46], denoting a decreasing trend. On the other hand, the odds ratio was very high in some regions, such as Hokkaido (6.66 [5.24, 8.48]), indicating that the administration trend varied by region.

CONCLUSIONS

The increase in the proportion of steroid use showed the same trend nationwide, although the rate of increase differed, confirming that the use of drugs with proven efficacy was spreading rapidly and that effective treatment was available nationwide. However, the results suggest that drugs such as favipiravir, which were initially expected to be effective, may continue to be administered. Registry studies include larger populations than clinical trials and enable real-time monitoring of medication status and trends. Further use of registry studies for treatment standardization is expected in the future.

Clinical characteristics and courses of 200 patients hospitalized for COVID-19 during the second and third waves at Fujita Health University Okazaki Medical Center in Japan

Objectives

There are few reports about patients hospitalized for COVID-19 in Japan. We investigated 200 patients hospitalized for COVID-19 over a 6-month period with the aim of elucidating their clinical characteristics and clinical courses.

Methods

The study cohort comprised 200 patients hospitalized for COVID-19 during a 6-month period. We examined baseline characteristics, source of transmission, preadmission course, initial symptoms, concomitant symptoms, comorbidities, treatments, and prognosis.

Results

The number of inpatients from outside our region increased from 9 in the second wave to 53 in the third wave. The initial manifestations were cold-like and gastroenteritis-like symptoms, gustatory and olfactory dysfunction being frequently occurring concomitant symptoms. On admission 32 patients had mild disease, 108 moderate I, 54 moderate II, and 6 severe. We divided the 200 patients into second and third wave groups and compared their baseline characteristics. The third wave group was older and had more severe disease. The main treatments implemented were dexamethasone and remdesivir. Three patients (1.5%) required ventilation and 12 (6.0%) died in hospital.

Conclusions

We investigated 200 patients hospitalized for COVID-19 over a period of 6 months. The patients in the second wave were relatively young and most had mild disease. In contrast, the patients in the third wave were older and had more severe disease and higher in-hospital mortality.

The Impact and Treatment of COVID-19 in Hemodialysis Patients

BACKGROUND

Patients with coronavirus disease 2019 (COVID-19) undergoing maintenance hemodialysis have a poor prognosis and limited treatment options.

METHODS

This paper outlines the impact of COVID-19, its treatment, and the efficacy of vaccines in Japanese patients undergoing hemodialysis with a review of the literature.

RESULTS

Patients undergoing dialysis in dialysis facilities are at greater risk of exposure to severe acute respiratory syndrome coronavirus 2 than the general population due to limited isolation capabilities. Therefore, vaccines are expected to be effective for patients undergoing dialysis. In addition, effective use of available medications is important because treatment options are limited.

CONCLUSIONS

Efforts should be made to prevent the spread of the infection to high-risk patients undergoing dialysis while ensuring the effective use of vaccines.

Clinical significance of prediabetes, undiagnosed diabetes and diagnosed diabetes on critical outcomes in COVID-19: Integrative analysis from the Japan COVID-19 task force

AIM

Diabetes mellitus (DM) is a known risk factor for severe coronavirus disease 2019 (COVID-19), but the clinical impact of undiagnosed diabetes and prediabetes in COVID-19 are unclear particularly in Japan. We clarify the difference in clinical characteristics, including age, sex, body mass index and co-morbidities, laboratory findings and critical outcomes, in a large Japanese COVID-19 cohort without diabetes, with prediabetes, undiagnosed diabetes and diagnosed diabetes, and to identify associated risk factors.

MATERIALS AND METHODS

This multicentre, retrospective cohort study used the Japan COVID-19 Task Force database, which included data on 2430 hospitalized COVID-19 patients from over 70 hospitals from February 2020 to October 2021. The prevalence of prediabetes, undiagnosed diabetes and diagnosed diabetes were estimated based on HbA1c levels or a clinical diabetes history. Critical outcomes were defined as the use of high-flow oxygen, invasive positive-pressure ventilation or extracorporeal membrane oxygenation, or death during hospitalization.

RESULTS

Prediabetes, undiagnosed diabetes and diagnosed diabetes were observed in 40.9%, 10.0% and 23.0%, respectively. Similar to diagnosed diabetes, prediabetes and undiagnosed diabetes were risk factors for critical COVID-19 outcomes (adjusted odds ratio [aOR] [95% CI]: 2.13 [1.31-3.48] and 4.00 [2.19-7.28], respectively). HbA1c was associated with COVID-19 severity in prediabetes patients (aOR [95% CI]: 11.2 [3.49-36.3]), but not other groups.

CONCLUSIONS

We documented the clinical characteristics and outcomes of Japanese COVID-19 patients according to HbA1c levels or diabetes co-morbidity. As well as undiagnosed and diagnosed diabetes, physicians should be aware of prediabetes related to COVID-19 severity.

Diabetic ketoacidosis after the second dose of SARS-CoV-2 mRNA vaccination in a patient with pembrolizumab-induced fulminant type 1 diabetes

We report a case of 77-year-old woman with fulminant type 1 diabetes (T1D) who developed diabetic ketoacidosis (DKA) after the second dose of SARS-CoV-2 vaccine tozinameran. The patient had been diagnosed as having T1D associated with an immune-related adverse event caused by pembrolizumab at the age of 75. After the second dose of tozinameran, she developed DKA and needed intravenous insulin infusion and mechanical ventilation. Although the direct causal relationship between the vaccination and the DKA episode could not be proven in this case, published literatures had suggested the possibility of developing DKA after SARS-CoV-2 vaccination in patients with T1D. As the magnitude of the risk of the combination of the known adverse drug reactions of SARS-CoV-2 mRNA vaccine and T1D patients' vulnerability to sick-day conditions is not yet thoroughly assessed, future studies such as a non-interventional study with adequate sample size would be required to address this issue.

Mixing age and risk groups for accessing COVID-19 vaccines: a modelling study

OBJECTIVE

To characterise the optimal targeting of age and risk groups for COVID-19 vaccines.

DESIGN

Motivated by policies in Japan and elsewhere, we consider rollouts that target a mix of age and risk groups when distributing the vaccines. We identify the optimal group mix for three policy objectives: reducing deaths, reducing cases and reducing severe cases.

SETTING

Japan, a country where the rollout occurred over multiple stages targeting a mix of age and risk groups in each stage.

PRIMARY OUTCOMES

We use official statistics on COVID-19 deaths to quantify the virus transmission patterns in Japan. We then search over all possible group mix across rollout stages to identify the optimal strategies under different policy objectives and virus and vaccination conditions.

RESULTS

Low-risk young adults can be targeted together with the high-risk population and the elderly to optimally reduce deaths, cases and severe cases under high virus transmissibility. Compared with targeting the elderly or the high-risk population only, applying optimal group mix can further reduce deaths and severe cases by over 60%. High-efficacy vaccines can mitigate the health loss under suboptimal targeting in the rollout.

CONCLUSIONS

Mixing age and risk groups outperforms targeting individual groups separately, and optimising the group mix can substantially increase the health benefits of vaccines. Additional policy measures boosting vaccine efficacy are necessary under outbreaks of transmissible variants.

Clinical characteristics of COVID-19 patients with underlying rheumatic diseases in Japan: data from a multicenter observational study using the COVID-19 Global Rheumatology Alliance physician-reported registry

INTRODUCTION

To describe clinical characteristics of patients in Japan with coronavirus disease 19 (COVID-19) and pre-existing rheumatic disease and examine the possible risk factors associated with severe COVID-19.

METHODS

Adults with rheumatic disease and a COVID-19 diagnosis who were registered in the COVID-19 Global Rheumatology Alliance (C19-GRA) physician-reported registry from Japan between 15 May 2020 and 12 May 2021 were included. Multivariable logistic regression models were used to assess factors associated with severe COVID-19 progression, defined as death or requiring oxygen inhalation.

RESULTS

In total, 222 patients were included in the study. Rheumatoid arthritis (48.2%), gout (14.4%), and systemic lupus erythematosus (8.1%) were the most common types of rheumatic disease, 55.1% of patients were in remission and 66.2% had comorbid disease. Most patients were hospitalised (86.9%) for COVID-19, 43.3% received oxygen, and 9.0% died. Older age (≥ 65 years), corticosteroid use, comorbid diabetes, and lung diseases are associated with higher risk for severe COVID-19 progression (odds ratio (OR) 3.52 [95% confidence interval (CI) 1.69-7.33], OR 2.68 [95% CI 1.23-5.83], OR 3.56 [95% CI 1.42-8.88], and OR 2.59 [95% CI 1.10-6.09], respectively).

CONCLUSIONS

This study described clinical characteristics of COVID-19 patients with rheumatic diseases in Japan. Several possible risk factors for severe COVID-19 progression were suggested. Key points • Clinical characteristics of 222 adult patients in Japan with coronavirus disease 19 (COVID-19) and pre-existing rheumatic diseases were described. • Most patients were hospitalised (86.9%) for COVID-19 in Japan, 43.3% received oxygen, and 9.0% died. • The COVID-19 characteristics of patients with rheumatic diseases did not show any obvious different pattern from those of the general population in Japan. • In this study, older age (≥ 65 years), corticosteroid use, comorbid diabetes, and lung diseases are associated with higher risk for severe COVID-19 progression.

Statistical Analysis of Mortality Rates of Coronavirus Disease 2019 (COVID-19) Patients in Japan Across the 4C Mortality Score Risk Groups, Age Groups, and Epidemiological Waves: A Report From the Nationwide COVID-19 Cohort

Background

The mortality rates of coronavirus disease 2019 (COVID-19) have been changed across the epidemiological waves. The aim was to investigate the differences in mortality rates of COVID-19 patients in Japan across the 6 epidemiological waves stratified by age group and Coronavirus Clinical Characterisation Consortium (4C) mortality score risk group.

Methods

A total of 56 986 COVID-19 patients in the COVID-19 Registry Japan from 2 March 2020 to 1 February 2022 were enrolled. These patients were categorized into 4 risk groups based on their 4C mortality score. Mortality rates of each risk group were calculated separately for different age groups: 18-64, 65-74, 75-89, and ≥90 years. In addition, mortality rates across the wave periods were calculated separately in 2 age groups: <75 and ≥75 years. All calculated mortality rates were compared with reported data from the United Kingdom (UK) during the early epidemic.

Results

The mortality rates of patients in Japan were significantly lower than in the UK across the board, with the exception of patients aged ≥90 years at very high risk. The mortality rates of patients aged ≥75 years at very high risk in the fourth and fifth wave periods showed no significant differences from those in the UK, whereas those in the sixth wave period were significantly lower in all age groups and in all risk groups.

Conclusions

The present analysis showed that COVID-19 patients had a lower mortality rate in the most recent sixth wave period, even among patients ≥75 years old at very high risk.