Publications by authors named "Nobuaki Matsunaga"

Article Synopsis
  • Co-infection with other viruses can worsen the severity of COVID-19 in children, but research on this topic is still limited, particularly in the context of the Omicron variant.
  • A study of 245 hospitalized pediatric COVID-19 patients found that 31.8% had co-infections, mainly with enterovirus/rhinovirus, and these patients exhibited more respiratory symptoms and a higher need for oxygen support.
  • The analysis identified co-infection and existing comorbidities as significant risk factors for requiring oxygen therapy in these pediatric patients.
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This study aimed to clarify changes in antimicrobial prescribing trends in pediatric clinics before and after the chronic shortage of amoxicillin and amoxicillin-clavulanic acid from 2023 in Japan. Amoxicillin and amoxicillin-clavulanic acid have been in chronic short supply since May 24, 2023 due to increased demand. It is unclear whether this situation has changed the type of oral antimicrobials prescribed by clinics.

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Background: Evaluating the selective pressure of antimicrobials on bacteria is important for promoting antimicrobial stewardship programs (ASPs). The aim of this study was to assess the selective pressure of antimicrobials by evaluating their use (carbapenem [CBP] and CBP-sparing therapy) over time and the detection status of CBP-resistant organisms using multicenter data.

Methods: Among the facilities whose data were registered in the Japan Surveillance for Infection Prevention and Healthcare Epidemiology from 2017 to 2020, those that had data on the use of CBP and CBP-sparing therapy (fluoroquinolones [FQs], cefmetazole [CMZ], piperacillin-tazobactam [PIP/TAZ], ampicillin-sulbactam [ABPC/SBT], ceftriaxone/cefotaxime [CTRX/CTX], CAZ (ceftazidime), cefepime [CFPM], and aminoglycosides [AGs]) as well as on CBP-resistant Enterobacterales (CRE) and CBP-resistant Pseudomonas aeruginosa (CRPA) detection were included.

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Introduction: Comprehensive evidence about the burden of infectious diseases in the Western Pacific Region is scarce. We thus examined the disease burden of infectious diseases in Japan in terms of disability-adjusted life years (DALYs).

Methods: We extracted national claims data from Japan's universal health insurance system to estimate the burden of disease for selected infections between 2015 and 2020 using DALYs.

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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, 10 revision code: U07.

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Article Synopsis
  • Monitoring antibiotic-resistant bacteria (ARB) and understanding their impact on the human microbiome and resistome is essential for public health, especially in long-term care facilities where residents often harbor ARB.
  • This study used shotgun metagenome sequencing on oral and stool samples from these residents to analyze the effects of antimicrobial treatment, finding increased abundance of certain archaea and antimicrobial resistance genes (ARGs) in those with recent treatment histories.
  • Interestingly, the research showed that taxonomic diversity in gut microbiota did not decrease during antimicrobial treatment, indicating that the impact of a single drug might be less significant than previously believed, particularly in older adults.
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Article Synopsis
  • Few studies in Asia have assessed how effective COVID-19 mRNA vaccines are in preventing disease severity and death after hospitalization, particularly during the delta and omicron variants.
  • A cohort study in Japan analyzed data from vaccinated and unvaccinated individuals, showing that while full vaccination significantly reduced the need for oxygen therapy and mortality during the omicron phase, booster doses offered limited additional benefits.
  • The findings suggest that while full vaccination is effective in lowering disease severity, booster doses might not provide further protection, indicating that vaccination strategies should adapt based on the dominant variant.
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  • A study was conducted in Japan to compare the effectiveness of tocilizumab, a therapeutic agent for COVID-19 pneumonia, against the standard of care (SOC) for severe cases.
  • The research utilized data from two databases, analyzing the time to discharge and other clinical outcomes between the tocilizumab and SOC groups.
  • Results indicated a slightly shorter median discharge time for tocilizumab (15 days) compared to SOC (16 days), but no significant difference was found in other clinical improvement metrics.
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: Dexamethasone's (DEXA) beneficial effect on survival when administered to critically ill patients with coronavirus disease 2019 (COVID-19) has been documented in randomized trials and meta-analyses. Here, we conducted this study to clarify the association between time from COVID-19 onset to steroid initiation and mortality and to examine the factors underlying these results.: This was a multicenter, retrospective, observational study of patients enrolled in the Japanese COVID-19 Registry from January 1, 2020, to April 30, 2021.

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Background: The cumulative antibiogram is essential to guide empirical therapy for infectious diseases and monitor the trend of antimicrobial resistance. However, the status of antibiogram generation at medical institutions in Japan is uncertain.

Methods: A web-based questionnaire survey was conducted in February 2023 on the status of antibiogram preparation among facilities participating in the Japan Surveillance for Infection Prevention and Healthcare Epidemiology (J-SIPHE), an infection control surveillance system in Japan.

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Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.5 became prevalent in July 2022 in Japan. Bivalent messenger RNA (mRNA) vaccines were approved as booster doses for individuals who received the primary series or booster dose by monovalent vaccines.

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Background: We evaluated the effectiveness of the BNT162b2 vaccine against infection, symptomatic infection, and hospitalization in older people during the Delta-predominant period (July 1 to September 30, 2021).

Methods: We performed a population-based cohort study in an older adult population aged ≥65 years using data from the Vaccine Effectiveness, Networking, and Universal Safety Study conducted from January 1, 2019, to September 30, 2021, in Japan. We matched BNT162b2-vaccinated and -unvaccinated individuals in a 1:1 ratio on the date of vaccination of the vaccinated individual.

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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.

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Introduction: The latest therapeutic drug monitoring guidelines for vancomycin (VCM) recommend that area under the concentration-time curve is estimated based on model-informed precision dosing and used to evaluate efficacy and safety. Therefore, we predicted VCM concentrations in individual methicillin-resistant Staphylococcus aureus-infected patients using existing a physiologically based pharmacokinetic (PBPK) model and 1- and 2-compartment population pharmacokinetic (PPK) models and confirmed and verified the accuracy of the PBPK model in estimating VCM concentrations with the PPK model.

Methods: The subjects of the study are 20 patients, and the predicted concentrations were evaluated by comparing the observed and predicted trough and peak values of VCM concentrations for individual patients.

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Introduction: Antimicrobial resistance (AMR) is a major global health threat. While antimicrobial consumption (AMC) in Japan substantially decreased after implementation of the AMR National Action Plan, the disease burden due to AMR seems to be unchanged. The main objective of this study is to examine the relationship between AMC and the disease burden due to AMR in Japan.

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Article Synopsis
  • The effectiveness of remdesivir for treating COVID-19 in children is not well-established.
  • A study compared children receiving remdesivir with those who did not, revealing that more in the remdesivir group had a reduction in fever by Day 4 (86.7% vs 73.3%).
  • However, the difference in fever reduction between the two groups was not statistically significant (P = 0.333).
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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.

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  • The study aimed to examine the changing mortality rates of COVID-19 patients in Japan across six waves, with a focus on age groups and risk levels.
  • A total of 56,986 patients were analyzed, categorized by age and a mortality risk score, revealing significant differences in mortality rates compared to the UK.
  • Results indicated that while Japanese patients generally had lower mortality rates than those in the UK, older patients (≥75 years) at very high risk experienced similar rates during the fourth and fifth waves, but showed improved survival in the sixth wave.
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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.

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The risk factors specific to the elderly population for severe coronavirus disease 2019 (COVID-19) caused by the Omicron variant of concern (VOC) are not yet clear. We performed an exploratory analysis using logistic regression to identify risk factors for severe COVID-19 illness among 4,868 older adults with a positive severe acute respiratory coronavirus 2 (SARS-CoV-2) test result who were admitted to a healthcare facility between 1 January 2022 and 16 May 2022. We then conducted one-to-one propensity score (PS) matching for three factors - dementia, admission from a long-term care facility and poor physical activity status - and used Fisher's exact test to compare the proportion of severe COVID-19 cases in the matched data.

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Article Synopsis
  • - The study analyzed COVID-19 patients in Japan, comparing the characteristics of 28,093 Japanese patients with 1,335 non-Japanese patients, including East Asians, South Asians, and Latin Americans, based on data collected before March 31, 2021.
  • - Non-Japanese patients were generally younger and more frequently exposed to COVID-19 risks through travel, social dining, and working in crowded environments, but there were no significant differences in clinical outcomes between the groups.
  • - Minorities showed less severe disease risk but faced higher exposure rates, suggesting equal access to care in Japan's healthcare system; however, more investigation is needed into their social health determinants.
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The COVID-19 Registry Japan (COVIREGI-JP), a registry of patients hospitalized with coronavirus disease (COVID-19), contains the largest national COVID-19 inpatient population. Since COVIREGI-JP invites voluntary participation by facilities, selection bias is inevitable. The current study examined the representativeness of COVIREGI-JP data in comparison to open-source national data.

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The impact of the COVID-19 pandemic on the incidence of microbial infections and other metrics related to antimicrobial resistance (AMR) has not yet been fully described. Using data from Japan Surveillance for Infection Prevention and Healthcare Epidemiology (J-SIPHE), a national surveillance database system that routinely collects clinical and epidemiological data on microbial infections, infection control practices, antimicrobial use, and AMR emergence from participating institutions in Japan, we assessed the temporal changes in AMR-related metrics before and after the start of the COVID-19 pandemic. We found that an apparent decrease in the incidence of microbial infections in 2020 compared with 2019 may have been driven primarily by a reduction in bed occupancy, although the incidence showed a constant or even slightly increasing trend after adjusting for bed occupancy.

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