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We aimed to elucidate the dynamic changes in short-chain fatty acids (SCFA) produced by the gut microbiota following smoking exposure and their role in chronic obstructive pulmonary disease (COPD) pathogenesis. SCFA concentrations were measured in human plasma, comparing non-smokers (n = 6) and smokers (n = 12). Using a mouse COPD model induced by cigarette smoke exposure or elastase-induced emphysema, we modulated SCFA levels through dietary interventions and antibiotics to evaluate their effects on inflammation and alveolar destruction. Human smokers showed lower plasma SCFA concentrations than non-smokers, with plasma propionic acid positively correlating with forced expiratory volume in 1 s/forced vital capacity. Three-month smoking-exposed mice demonstrated altered gut microbiota and significantly reduced fecal SCFA concentrations compared to air-exposed controls. In these mice, a high-fiber diet increased fecal SCFAs and mitigated inflammation and alveolar destruction, while antibiotics decreased fecal SCFAs and exacerbated disease features. However, in the elastase-induced model, fecal SCFA concentration remained unchanged, and high-fiber diet or antibiotic interventions had no significant effect. These findings suggest that smoking exposure alters gut microbiota and SCFA production through its systemic effects. The anti-inflammatory properties of SCFAs may play a role in COPD pathogenesis, highlighting their potential as therapeutic targets., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objectives: To assess the value of serum ferritin and Krebs von den Lungen-6 (KL-6) levels for predicting severe COVID-19 (death or requirement for invasive mechanical ventilation [IMV]/high-flow oxygen)., Methods: Data were analyzed on 2495 patients with COVID-19 from February 2020 to November 2022 using data from a nationwide COVID-19 database., Results: Patients with high KL-6 and low ferritin levels were older with more comorbidities and higher mortality rates, whereas those with high ferritin and low KL-6 levels were younger, predominantly male, and more likely to need IMV. A high level of both markers was strongly associated with critical outcomes (adjusted odds ratio: 13.6, 95% confidence interval: 8.58-21.5). The combination of both markers had higher predictive value than either marker alone (area under the curve: 0.709, 0.745, and 0.781 for KL-6, ferritin, and KL-6 + ferritin, respectively)., Conclusions: The combination of both markers accurately predicted COVID-19 severity., Competing Interests: Declaration of competing interest The authors have no conflicts of interest., (Copyright © 2024 The Author. Published by Elsevier B.V. All rights reserved.)

Background: Patients often experience multiple prolonged symptoms following acute coronavirus disease 2019 (COVID-19) recovery, defined as long coronavirus disease (COVID). Patients with long COVID may experience dyspnea during acute and post-acute phases. Therefore, this study aimed to identify specific risk factors for dyspnea in patients with long COVID., Methods: Hospitalized patients with COVID-19, aged ≥18 years, were enrolled in this multicenter cohort study conducted at 26 medical institutions across Japan. Clinical data during hospitalization and patient-reported outcomes after discharge at the 3, 6, and 12-month follow-ups were retrieved from medical records and paper-based or smartphone application-based questionnaires, respectively., Results: Generalized linear mixed model (GLMM) analysis of prolonged dyspnea at each time point during follow-up showed that this symptom was associated with chronic obstructive pulmonary disease (COPD) (odds ratio [OR], 2.74; 95% confidence interval [CI], 1.31-5.74), asthma (OR, 2.21; 95%CI, 1.17-4.16), and ventilator management (OR, 3.10; 95%CI, 1.65-5.83). In addition, patients with COPD (44.4%) and ventilator management (25.0%) were more frequently associated with delayed dyspnea onset. The generalized estimating equations analysis results with multiple imputed datasets, conducted as a sensitivity analysis, confirmed the adjusted GLMM analysis results., Conclusions: Prolonged dyspnea was associated with COPD, asthma, and severe infection that required mechanical ventilation in the Japanese population with long COVID. Further investigation is needed to clarify its mechanism and develop prophylactic and therapeutic strategies for dyspnea in patients with long COVID., (Copyright © 2024 [The Author]. Published by Elsevier B.V. All rights reserved.)

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., Competing Interests: Declaration of Competing interest The authors have no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Background: Multiple prolonged symptoms are observed in patients who recover from an acute COVID-19 infection, which is defined as long COVID. General fatigue is frequently observed in patients with long COVID during acute and post-acute phases. This study aimed to identify the specific risk factors for general fatigue in long COVID., Methods: Hospitalized patients with COVID-19 aged over 18 years were enrolled in a multicenter cohort study at 26 medical institutions. Clinical data during hospitalization and patient-reported outcomes after discharge were collected from medical records, paper-based questionnaires, and smartphone apps., Results: Among prolonged symptoms through 1-year follow-ups, general fatigue was the most interfering symptom in daily life. Patients with protracted fatigue at all follow-up periods had lower quality of life scores at the 12-month follow-up. Univariate logistic regression analysis of the presence or absence of general fatigue at the 3-month, 6-month, and 12-month follow-ups identified asthma, younger age, and female sex as risk factors for prolonged fatigue. Multivariable logistic regression analysis revealed that asthma was an independent risk factor for persistent fatigue during the 12-month follow-up period. Longitudinal changes in the symptoms of patients with or without asthma demonstrated that general fatigue, not cough and dyspnea, was significantly prolonged in patients with asthma., Conclusions: In a Japanese population with long COVID, prolonged general fatigue was closely linked to asthma. A preventive approach against COVID-19 is necessary to avoid sustained fatigue and minimize social and economic losses in patients with asthma., (Copyright © 2023 Japanese Society of Allergology. Published by Elsevier B.V. All rights reserved.)

BACKGROUND ＆ AIMS: Muscle quantification using chest computed tomography (CT) is a useful prognostic biomarker for coronavirus disease 2019 (COVID-19). However, no studies have evaluated the clinical course through comprehensive assessment of the pectoralis and erector spinae muscles. Therefore, we compared the impact of the areas and densities of these muscles on COVID-19 infection outcome., Methods: This multicenter retrospective cohort study was conducted by the COVID-19 Task Force. A total of 1410 patients with COVID-19 were included, and data on the area and density of the pectoralis and erector spinae muscles on chest CT were collected. The impact of each muscle parameter on the clinical outcome of COVID-19 was stratified according to sex. The primary outcome was the percentage of patients with severe disease, including those requiring oxygen supplementation and those who died. Additionally, 167 patients were followed up for changes in muscle parameters at three months and for the clinical characteristics in case of reduced CT density., Results: For both muscles, low density rather than muscle area was associated with COVID-19 severity. Regardless of sex, lower erector spinae muscle density was associated with more severe disease than pectoralis muscle density. The muscles were divided into two groups using the receiver operating characteristic curve of CT density, and the population was classified into four (Group A: high CT density for both muscles, Group B: low CT density for pectoralis and high for erector spinae muscle. Group C: high CT density for pectoralis and low for erector spinae muscle, Group D: low CT density for both muscles). In univariate analysis, Group D patients exhibited worse outcomes than Group A (OR: 2.96, 95% CI: 2.03-4.34 in men; OR: 3.02, 95% CI: 2.66-10.4 in women). Multivariate analysis revealed that men in Group D had a significantly more severe prognosis than those in Group A (OR: 1.82, 95% CI: 1.16-2.87). Moreover, Group D patients tended to have the highest incidence of other complications due to secondary infections and acute kidney injury during the clinical course. Longitudinal analysis of both muscle densities over three months revealed that patients with decreased muscle density over time were more likely to have severe cases than those who did not., Conclusions: Muscle density, rather than muscle area, predicts the clinical outcomes of COVID-19. Integrated assessment of pectoralis and erector spinae muscle densities demonstrated higher accuracy in predicting the clinical course of COVID-19 than individual assessments., Competing Interests: Conflict of Interest The authors declare that they have no conflicts of interest., (Copyright © 2024 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Background: Effective use of lung volume data measured on computed tomography (CT) requires reference values for specific populations. This study examined whether an equation previously generated for multiple ethnic groups in the United States, including Asians predominantly composed of Chinese people, in the Multi-Ethnic Study of Atherosclerosis (MESA) could be used for Japanese people and, if necessary, to optimize this equation. Moreover, the equation was used to characterize patients with chronic obstructive pulmonary disease (COPD) and lung hyperexpansion., Methods: This study included a lung cancer screening CT cohort of asymptomatic never smokers aged ≥40 years from two institutions (n = 364 and 419) to validate and optimize the MESA equation and a COPD cohort (n = 199) to test its applicability., Results: In all asymptomatic never smokers, the variance explained by the predicted values (R 2 ) based on the original MESA equation was 0.60. The original equation was optimized to minimize the root mean squared error (RMSE) by adjusting the scaling factor but not the age, sex, height, or body mass index terms of the equation. The RMSE changed from 714 ml in the original equation to 637 ml in the optimized equation. In the COPD cohort, lung hyperexpansion, defined based on the 95th percentile of the ratio of measured lung volume to predicted lung volume in never smokers (122 %), was observed in 60 (30 %) patients and was associated with centrilobular emphysema and air trapping on inspiratory/expiratory CT., Conclusions: The MESA equation was optimized for Japanese middle-aged and elderly adults., Competing Interests: Declaration of competing interest N.T. and T.H. received research grants from Daiichi Sankyo and FUJIFILM Co., Ltd., outside of the submitted work. S.S. received grants from Nippon Boehringer Ingelheim, Philips-Respironics, Fukuda Denshi, Fukuda Lifetec Keiji, and ResMed outside of the submitted work. None of these companies played a role in the design or analysis of the study or the writing of the manuscript. The other authors have no conflicts of interest., (Copyright © 2023. Published by Elsevier B.V.)

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., Competing Interests: Conflict of Interest Norihiro Harada reports personal fees from AstraZeneca K.K., GlaxoSmithKline, Kyorin, Novartis Japan, Sanofi and grants from AstraZeneca, Daikin, Kyorin, SRL Medisearch, outside the submitted work. Other authors have no conflicts of interest., (Copyright © 2023. Published by Elsevier B.V.)

Background: Differences in the clinical impacts of fat mass index (FMI) and fat-free mass index (FFMI) remain unclear in patients with chronic obstructive pulmonary disease (COPD). We hypothesized that FMI and FFMI have different impacts on 1) emphysema and 2) pulmonary function and health-related quality of life of COPD patients., Methods: Patients with COPD (n = 228), enrolled in a multicenter prospective 3-year cohort were classified into four groups based on baseline median FMI and FFMI values. Emphysema assessed as the ratio of low attenuation area to total lung volume (LAA%) on computed tomography, pulmonary function, and health-related quality of life assessed using the St. George's Respiratory Questionnaire (SGRQ) were compared., Results: The four groups had statistically significant differences in LAA%, pulmonary function, and SGRQ scores. The Low FMI Low FFMI group exhibited the highest LAA%, lowest pulmonary function, and worst SGRQ scores among the four groups. In addition, these differences were consistent over 3 years. Multivariate analysis showed that low FMI was associated with high LAA%, low inspiratory capacity/total lung capacity (IC/TLC), and carbon monoxide transfer coefficient (K CO ). In contrast, low FFMI was associated with these factors as well as worse SGRQ scores., Conclusion: FMI and FFMI have different effects on the clinical manifestations of COPD. Both low fat and muscle mass contributed to severe emphysema, whereas only low muscle mass contributed to worse health-related quality of life in patients with COPD., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objectives: Although SARS-CoV-2 RNAemia has been reported to strongly impact patients with severe COVID-19, the clinical characteristics of patients with COVID-19 harboring detectable intracellular SARS-CoV-2 RNA remain unknown., Methods: We included adult patients who had developed COVID-19 between February and September 2020. Total white blood cells derived from the buffy coat of peripheral whole blood were used to detect SARS-CoV-2 RNA using the Illumina COVIDSeq test. We compared the clinical characteristics between patients with and without detected viral RNA (detected and undetected groups)., Results: Among the 390 patients included, 17 harbored SARS-CoV-2 RNA in peripheral white blood cells. All 17 patients required oxygen support during the disease course and had higher intensive care unit admission (52.9% vs 28.9%, P = 0.035), mortality (17.7% vs 3.5%, P = 0.004), kidney dysfunction (severe, 23.5% vs 6.4%, P = 0.029), and corticosteroid treatment rates (76.5% vs 46.5%, P = 0.016) than those of patients in the undetected group., Conclusion: We propose that patients with circulating intracellular SARS-CoV-2 RNA in the peripheral blood exhibited the most severe disease course., Competing Interests: Declaration of Competing Interest The authors have no competing interests to declare., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

We investigated the association between complete blood count, including neutrophil-to-lymphocyte ratio (NLR) in combination with patient characteristics, and coronavirus disease (COVID-19) outcomes to identify the best prognostic indicator. We analyzed data of patients with confirmed COVID-19 from the nationwide database of the Japan COVID-19 Task Force between February 2020 and November 2021. A composite outcome was defined as the most severe condition, including noninvasive positive-pressure ventilation, high-flow nasal cannula, invasive mechanical ventilation, extracorporeal membrane oxygenation, or death. Of 2425 patients in the analysis, 472 (19.5%) experienced a composite outcome. NLR was the best predictor of composite outcomes, with an area under the curve (AUC) of 0.81, and a sensitivity and specificity of 72.3% and 75.7%, respectively, using a cut-off value of 5.04. The combination of NLR and an oxygen requirement on admission had the highest AUC (0.88). This simple combination may help identify patients at risk of progression to severe disease., Competing Interests: Conflict of Interest The authors have no conflicts of interest., (Copyright © 2023 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.)

Objectives: COVID-19 was severe in the Delta variant-dominated epidemic wave (fifth wave) in Japan. The clinical characteristics and effectiveness of COVID-19 vaccination are not fully understood in the Omicron variant-dominated wave (sixth and seventh waves), especially in hospitalized patients. We investigated the relationship between vaccination and disease severity in the Omicron-dominated wave and compared these variant-dominated waves., Methods: The nationwide COVID-19 database (Japan COVID-19 Task Force) was used to compare clinical characteristics and critical outcomes in patients hospitalized with Delta (fifth, N = 735) vs Omicron-dominated waves (sixth, N = 495; seventh, N = 128)., Results: Patients in the sixth and seventh waves had a lower incidence of critical outcomes and respiratory outcomes, and a higher incidence of bacterial infection, although the mortality rate did not differ significantly between waves. In the sixth and seventh waves, 138 (27.9%) and 29 (22.7%) patients with COVID-19 were unvaccinated, respectively. Multivariable analysis adjusted with previously reported factors revealed that the proportion of (1) critical outcomes and (2) respiratory outcomes decreased in a frequency-dependent manner. Thus, (1) (the number of vaccinations): 1-2 times: adjusted odds ratio (aOR) 0.37 (95% confidence interval [CI]; 0.20-0.69); 3-4 times: aOR 0.25 (95% CI; 0.11-0.58); and (2) 1-2 times: aOR 0.43 (95% CI; 0.27-0.66); 3-4 times: aOR 0.36 (95% CI; 0.21-0.60)., Conclusions: Patients hospitalized with COVID-19 with Omicron infections showed a lower incidence of critical outcomes than those with Delta infections, and COVID-19 vaccination may contribute to preventing respiratory failure., Competing Interests: Declarations of competing interests The authors have no competing interests to declare., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: We investigated the occurrence of non-respiratory bacterial and fungal secondary infections, causative organisms, impact on clinical outcomes, and association between the secondary pathogens and mortality in hospitalized patients with coronavirus disease 2019 (COVID-19)., Methods: This was a retrospective cohort study that included data from inpatients with COVID-19 from multiple centers participating in the Japan COVID-19 Taskforce (April 2020 to May 2021). We obtained demographic, epidemiological, and microbiological data throughout the course of hospitalization and analyzed the cases of COVID-19 complicated by non-respiratory bacterial infections., Results: Of the 1914 patients included, non-respiratory bacterial infections with COVID-19 were diagnosed in 81 patients (4.2%). Of these, 59 (3.1%) were secondary infections. Bacteremia was the most frequent bacterial infection, occurring in 33 cases (55.9%), followed by urinary tract infections in 16 cases (27.1%). Staphylococcus epidermidis was the most common causative organism of bacteremia. Patients with COVID-19 with non-respiratory secondary bacterial infections had significantly higher mortality, and a multivariate logistic regression analysis demonstrated that those with bacteremia (aOdds Ratio = 15.3 [5.97-39.1]) were at higher risk of death. Multivariate logistic regression analysis showed that age, male sex, use of steroids to treat COVID-19, and intensive care unit admission increased the risk for nosocomial bacteremia., Conclusions: Secondary bacteremia is an important complication that may lead to poor prognosis in cases with COVID-19. An appropriate medical management strategy must be established, especially for patients with concomitant predisposing factors., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2023 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

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., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Two spirometry criteria have been proposed for early chronic obstructive pulmonary disease (COPD) in young smokers: 1) forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC) < the lower limit of normal (LLN), and 2) FEV 1 decline ≥60 ml/year. These criteria have yet to be validated. This study explored clinical factors associated with these two spirometry criteria., Methods: This retrospective study analysed medical check-up data from 13,010 consecutive subjects aged <50 years who underwent current and 3 previous spirometry tests in Japan. Current ≥10 pack-year smokers were the main focus of analysis; those meeting one or more spirometry criteria were diagnosed with early COPD. Early COPD was categorized into three subtypes: FEV 1 /FVC < LLN and FEV 1 decline <60 ml/year (type 1), FEV 1 /FVC ≥ LLN and FEV 1 decline ≥60 ml/year (type 2), and FEV 1 /FVC < LLN and FEV 1 decline ≥60 ml/year (type 3)., Results: Of the 1579 current ≥ 10 pack-year smokers, 488 (30.9%) met the early COPD criteria. Multivariate multinomial logistic models adjusted for age, sex, height, body mass index (BMI) and smoking history indicated that past BMI increase and low exercise were associated with higher type 2 early COPD incidence (odds ratio (OR) [95% confidence interval (CI)] = 4.30 [3.10, 6.04], and 0.80 [0.69, 0.93], respectively) but not with higher type 1 incidence. A history of asthma was associated with higher type 3 incidence (OR [95% CI] = 1.98 [1.18, 3.07])., Conclusions: The 3 types of spirometry-based early COPD have different clinical factors. Their trajectories should be explored in longitudinal studies., Competing Interests: Declarations of competing interest None., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Objectives: This study aimed to identify the relationship between abnormal serum uric acid levels or a history of hyperuricemia and COVID-19 severity in the Japanese population., Methods: We included 1523 patients enrolled in the Japan COVID-19 Task Force cohort between February 2020 and May 2021. We compared the clinical characteristics, including co-morbidities, laboratory findings, and outcomes, particularly invasive mechanical ventilation (IMV), among patients with and without abnormal uric acid levels or a history of hyperuricemia., Results: Patients with high serum uric acid levels were older and had higher body weight and body mass index than those without. In addition, the multiple logistic regression analysis revealed a significant association between high serum uric acid levels or a history of hyperuricemia and an increased risk of IMV (odds ratio [OR] = 1.77; P = 0.03/OR = 1.56; P = 0.04). Moreover, patients with low uric acid levels on admission were also associated significantly with the requirement of IMV (OR = 5.09; P <0.0001)., Conclusion: Abnormal serum uric acid levels or a history of hyperuricemia were significantly associated with COVID-19 severity in the Japanese cohort., Competing Interests: Declaration of competing interest The authors have no competing interests to declare., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background and Design: The coronavirus disease (COVID-19) pandemic is having a devastating effect worldwide. Host genome differences between populations may influence the severity of COVID-19. The Japan COVID-19 Task Force is conducting host genome analysis of hospitalized patients with COVID-19 from more than 70 institutions nationwide in Japan. This report describes the clinical characteristics of patients enrolled to date., Results: The median (interquartile range) age of the 1674 patients included in the analysis was 59 (45-71) years, and more than half of the patients (66.2%) were male. Less than half of the patients (41.2%) had severe disease. The case fatality rate was 3.2%., Conclusions: Since this is a hospital-based study, the number of severe cases was relatively high, but the case fatality rate was relatively low, when compared to that of other countries. In the future, we will continue to enroll patients and conduct genome analyses of patients with COVID-19., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Rationale: Various determinants of osteoporosis have been previously identified. However, only a few longitudinal studies have examined related factors. We aimed to investigate factors predicting and modifying rapid decline of bone mineral density in patients with chronic obstructive pulmonary disease., Methods: We analyzed patients with chronic obstructive pulmonary disease whose bone mineral density were measured at least three times over three years (n = 111). We divided annual per cent changes of bone mineral density in different body parts into tertiles. Rapid decliners (n = 33) were defined as those with the largest decline in at least two parts; all other participants were defined as non-rapid decliners (n = 78)., Results: At enrollment, bone mineral density did not differ between the two groups. However, rapid decliners had a significantly greater rate of new vertebral fractures over 3 years compared with non-rapid decliners. On multivariate logistic regression analysis, age, moderate to severe emphysema, no daily exercise habits, and anemia increased the likelihood of rapid decliners. Furthermore, patients who newly started and continued bisphosphonate exhibited higher annual per cent changes of bone mineral density than did those without bisphosphonate use., Conclusions: A rapid decline in bone mineral density correlates to a higher likelihood of vertebral fracture. We clarified the predictors of bone mineral density decline and demonstrated that bisphosphonate use might modify bone mineral density in patients with chronic obstructive pulmonary disease., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objectives: To investigate the relationship between small pulmonary vessels and extent of emphysema on CT in individual lungs with chronic obstructive pulmonary disease (COPD)., Methods: Forty-nine patients were included. The percentage of cross-sectional area of vessels <5mm 2 (%CSA <5) and extent of emphysema were assessed., Results: Less than half of the COPD patients demonstrated an inverse correlation between %CSA <5 and percentage of low attenuation area (LAA%). In the remaining patients, %CSA <5 was homogeneously distributed., Conclusion: Not all patients with COPD demonstrated an inverse correlation of the distributions between %CSA <5 and LAA% in individual lungs., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: The chronic obstructive pulmonary disease (COPD) Assessment Test (CAT) is a subjective measure of quality of life. The aim of this study was to examine the characteristics of COPD patients with increasing CAT scores within 3 years., Methods: Keio University and its affiliate hospitals conducted an observational COPD cohort study over 3 years. St. George's Respiratory Questionnaire (SGRQ) and CAT were completed at baseline and annually thereafter. Patients who had at least 3 CAT scores were included (n = 315). The ΔCAT score/year and ΔSGRQ score/year were calculated by the slope between each of the measures and the date of measurement., Results: The median ΔCAT score/year was 0.4, and ΔCAT score/year was significantly correlated with ΔSGRQ total score/year. Using an annual cut-off CAT score of +2 points, patients who deteriorated (n = 79) were older, had lower %FEV 1 , and more severe emphysema on computed tomography scan at baseline than patients who did not deteriorate. The baseline value was not a determinant of subsequent changes in the CAT score. Longitudinal changes in the CAT score were positively correlated with those in the SGRQ score., Conclusions: Old age and severe COPD, not the CAT score at one time point, predicted worsening quality of life., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background and Objectives: Patients with chronic obstructive pulmonary disease (COPD) frequently suffer from various comorbidities. Recently, cluster analysis has been proposed to examine the phenotypic heterogeneity in COPD. In order to comprehensively understand the comorbidities of COPD in Japan, we conducted multicenter, longitudinal cohort study, called the Keio COPD Comorbidity Research (K-CCR). In this cohort, comorbid diagnoses were established by both objective examination and review of clinical records, in addition to self-report. We aimed to investigate the clustering of nineteen clinically relevant comorbidities and the meaningful outcomes of the clusters over a two-year follow-up period., Material and Methods: The present study analyzed data from COPD patients whose data of comorbidities were completed (n = 311). Cluster analysis was performed using Ward's minimum-variance method., Results: Five comorbidity clusters were identified: less comorbidity; malignancy; metabolic and cardiovascular; gastroesophageal reflux disease (GERD) and psychological; and underweight and anemic. FEV1 did not differ among the clusters. GERD and psychological cluster had worse COPD assessment test (CAT) and Saint George's respiratory questionnaire (SGRQ) at baseline compared to the other clusters (CAT: p = 0.0003 and SGRQ: p = 0.00046). The rate of change in these scores did not differ within 2 years. The underweight and anemic cluster included subjects with lower baseline ratio of predicted diffusing capacity (DLco/VA) compared to the malignancy cluster (p = 0.036)., Conclusions: Five clusters of comorbidities were identified in Japanese COPD patients. The clinical characteristics and health-related quality of life were different among these clusters during a follow-up of two years., (Copyright © 2016 Elsevier Ltd. All rights reserved.)