Published papers

Purpose: The incidence of invasive Group A Streptococcus (iGAS) infection and streptococcal toxic shock syndrome (STSS) is increasing. Early detection and diagnosis of cases that may progress to STSS are currently difficult. In this study, we aimed to identify biomarkers and emm type, one of the virulence factors, associated with STSS development. Methods: In this multicentre observational study including patients with iGAS infection (n = 305), we investigated the relative associations of host factors, clinical manifestations, biomarkers, and emm type with STSS. Results: The overall mortality rate was 15.4%; the fatality rate within 28 days of admission was higher in patients with STSS (67.9%, 38/56) than in those without (3.6%, 9/249). The most predominant type was emm1 (38%), detected in 73.2% of the patients with STSS. Risk factors for STSS identified by multivariable analysis included underlying kidney disease (odds ratio [OR], 10.7; 95% confidence interval [CI], 2.1–54.0, p = 0.004), bacteraemia without primary focus (OR, 3.6; 95% CI 1.2–11.1, p = 0.023), necrotizing fasciitis (OR, 8.7; 95% CI 2.6–29.4, p < 0.001), white blood cell count (WBC) < 4,000/µL (OR, 7.8; 95% CI 2.4–25.6, p = 0.001), serum creatine kinase (CK) ≥ 300 U/L (OR, 7.5; 95% CI 2.8–19.8, p < 0.001), and emm1 (OR, 5.2; 95% CI 2.0–13.4, p = 0.001). Conclusion: WBC < 4,000/µL and CK level ≥ 300 U/L on admission are additional relevant biomarkers for STSS prediction. The most predominant iGAS type, emm1, was significantly associated with STSS.

Introduction: Coronavirus disease 2019 (COVID-19) has drastically changed everyday life worldwide. This study aimed to determine how COVID-19 affected the characteristics and outcomes of patients with severe burn injury by examining a city-wide burn database in Tokyo. Patients and methods: A descriptive study was conducted in 14 burn centers using the Tokyo Burn Unit Association registry from 1999 to 2020. The pandemic started in 2020, while the stay-at-home order lasted from April to May. The demographics, mechanisms, severity, and clinical outcomes were assessed before and during these two time periods. Results: In total, 7061 patients with burn injury were enrolled. During the pandemic, there were less patients during the pandemic than previous years, except for April–May; this decreased toward the end of 2020. There were also more scald/contact burns in the upper extremity, less intended and assault injuries, shorter length of hospital stay, and lower in-hospital mortality. During the stay-at-home order, there was increased incidence of flame burns, inhalation injuries, and in-hospital mortality, as well as higher total body surface area of full-thickness burns. Conclusions: This study described the characteristics of burns during the COVID-19 pandemic. The association between the stay-at-home order and severity of burns should be further examined.

Introduction: This is a systematic review and meta-analysis of the efficacy of wound coverage using advanced dressings specifically for the prevention of surgical site infections (SSI) in gastrointestinal surgery, as part of the update of the SSI prevention guidelines of the Japan Society for Surgical Infection (JSSI). Methods: After searching CENTRAL, PubMed, and ICHUSHI-Web in July 2024, we included randomized controlled trials (RCTs) comparing advanced dressings and standard dressings for surgical wounds in gastrointestinal surgery (PROSPERO No. CRD42024569084). Three authors independently screened the RCTs. We assessed the risk of bias and certainty of the body of evidence for the extracted data. The primary outcome was superficial SSI, and the secondary outcomes were length of postoperative hospital stay, costs, and allergy. This study was partially supported by the JSSI. Results: A total of seven RCTs and 927 patients were included. The use of advanced dressings significantly lowered the risk of SSI compared to that associated with standard dressings (risk ratio: 0.54, 95% confidence intervals: 0.34–0.88). The certainty of the evidence was rated as moderate. According to the subgroup analysis, advanced dressings reduced the risk of SSI in colorectal surgery. Advanced dressings did not reduce the length of postoperative hospital stay or costs compared to that of standard dressings. Allergies were reported in only one patient using silver-impregnated dressings. Conclusion: The use of advanced dressings for primary wounds in gastrointestinal surgery was associated with a significantly lower risk of SSI than that associated with standard dressings.

Purpose: While follow-up CT and prophylactic embolization with angiography are often conducted during non-operative management (NOM) for BLSI, particularly in a high-grade injury, the utility of early repeated CT for preventing unexpected hemorrhage remains unclear. This study aimed to elucidate whether early follow-up computerized tomography (CT) within 7 days after admission would decrease unexpected hemostatic procedures on pediatric blunt liver and spleen injury (BLSI). Methods: A post-hoc analysis of a multicenter observational cohort study on pediatric patients with BLSI (2008–2019) was conducted on those who underwent NOM, in whom the timing of follow-up CT were decided by treating physicians. The incidence of unexpected hemostatic procedure (laparotomy and/or emergency angiography for ruptured pseudoaneurysm) and complications related to BLSI were compared between patients with and without early follow-up CT within 7 days. Inverse probability weighting with propensity scores adjusted patient demographics, comorbidities, mechanism and severity of injury, initial resuscitation, and institutional characteristics. Results: Among 1320 included patients, 552 underwent early follow-up CT. Approximately 25% of patients underwent angiography on the day of admission. The incidence of unexpected hemostasis was similar between patients with and without early repeat CT (8 [1.4%] vs. 6 [0.8%]; adjusted OR, 1.44 [0.62–3.34]; p = 0.40). Patients with repeat CT scans more frequently underwent multiple angiographies (OR, 2.79 [1.32–5.88]) and had more complications related to BLSI, particularly bile leak (OR, 1.73 [1.04–2.87]). Conclusion: Follow-up CT scans within 7 days was not associated with reduced unexpected hemostasis in NOM for pediatric BLSI.

Background: A health-economic evaluation related to COVID-19 is urgently needed to allocate healthcare resources efficiently; however, relevant medical cost data in Japan concerning COVID-19 are scarce. Methods: This cross-sectional study investigated the healthcare cost for hospitalized COVID-19 patients in 2021 at Keio University Hospital. We calculated the healthcare costs during hospitalization using hospital claims data and investigated the variables significantly related to the healthcare cost with multivariable analysis. Results: The median healthcare cost per patient for the analyzed 330 patients was Japanese yen (JPY) 1,304,431 (US dollars ~ 11,871) (interquartile range: JPY 968,349–1,954,093), and the median length of stay was 10 days. The median healthcare cost was JPY 798,810 for mild cases; JPY 1,113,680 for moderate I cases; JPY 1,643,909 for moderate II cases; and JPY 6,210,607 for severe cases. Healthcare costs increased by 4.0% for each additional day of hospitalization; 1.26 times for moderate I cases, 1.64 times for moderate II cases, and 1.84 times for severe cases compared to mild cases; and 2.05 times for cases involving ICU stay compared to those not staying in ICU. Conclusions: We clarified the healthcare cost for hospitalized COVID-19 patients by severity in a Japanese university hospital. These costs contribute as inputs for forthcoming health economic evaluations for strategies for preventing and treating COVID-19.

Background: We evaluated the outcomes of pediatric patients with blunt liver and spleen injury (BLSI) admitted to hospitals with pediatric intensive care units (PICUs). Methods: A post-hoc analysis of a multicenter observational study on pediatric patients (≤16 years) with BLSI at 83 hospitals between 2008 and 2019 was conducted. Thirty-day mortality and BLSI-associated adverse events were compared between patients treated in hospitals with and without PICUs. Estimated 30-day mortality was compared, adjusting for demographics, comorbidities, injury mechanism and severity, and resuscitative treatments using inverse probability weighting. Results: Among 1401 patients, 421 were treated in hospitals with PICUs and 207 were admitted to a PICU. The 30-day mortality was 3 (0.7 %) and 13 (1.3 %) in patients treated in hospitals with and without PICUs, respectively, and was comparable between the patients treated in PICUs and adult ICUs (1 [0.5 %] vs. 9 [1.9 %]). The adjusted 30-day mortality was lower in patients treated in hospitals with PICUs than in those treated in hospitals with adult ICUs (3 [0.2 %] vs. 13 [1.0 %]; odds ratio 0.22 [0.06–0.79]; p = 0.012) and in those treated in PICUs than in those treated in adult ICUs (2 [0.3 %] vs. 10 [1.5 %]; odds ratio 0.22 [0.05–0.98]; p = 0.041). BLSI-related adverse events were similar regardless of the PICU availability or admission, except for emergency hemostasis of ruptured pseudoaneurysm, which was fewer in patients treated in hospitals with PICUs. Conclusions: Adverse events, including 30-day mortality, were rare, regardless of PICU availability, and the adjusted 30-day mortality was lower in patients treated in PICUs.

Introduction: Injury prevention is valuable for pediatric burns at home. To develop future target of prevention, we aimed to elucidate characteristics and chronological changes of pediatric burn injuries at home in urban areas. Patients and Methods: We conducted a retrospective observational study using the database of the Tokyo Burn Unit Association, which comprises 14 tertiary burn centers, the Tokyo Fire Department, Tokyo Medical Association, and the Tokyo city government. We included pediatric patients aged ≤ 15 years who had a burn injury at home in the last 30 years and divided them into five groups at 6-year intervals. We compared the mechanism, severity, and outcome of burn injuries between the groups. Results: We included 1092 pediatric patients, with no significant chronological changes in the incidence of burn injuries at home (approximately 200 patients in each 6-year period). The median age was 1 year in all the groups. Flame burns decreased from 7.7 % to 1.6 %, whereas scald burns remained at > 80 %. The burn area decreased from 10 (5−16) % total body surface area (%TBSA) to 7 (3−11) %TBSA. The length of hospital stay was reduced from 6 to 2 days, and in-hospital mortality was 0.4–0.5 % in the last decade. Conclusions: The incidence of flame burns and burn area decreased over time with improving clinical outcomes in pediatric burns. The number of scald burns remained the same over time; thus, further social intervention is needed to prevent scald burns.

Introduction: The optimal distribution of burn centers remains unclear. We aimed to determine the appropriate number of burn centers per population (density) and examined a nationwide registry with the hypothesis that low-density burn centers would be associated with unfavorable outcomes. Patients and methods: A retrospective study was conducted using the Japanese Society of Burn Injury registry (2011–2021). Burn center density was defined as the number of burn centers per one million population in each prefecture, and centers were trisected on the basis of density. Hospital-free days until day 30 were compared between patients at high-, middle-, and low-density centers. Inverse probability weighting was conducted to adjust baseline characteristics, including age, burn mechanism, and burn severity. Results: We included 6764, 6209, and 2200 patients at high-, middle-, and low-density burn centers, respectively. After adjusting for patient demographics and burn severity, patients at high- and middle-density centers (≥0.4 centers per one million population) had longer hospital-free days compared with those at low-density centers (11 [0–23] vs 11 [0–23] vs 8 [0–22] days; p < 0.001). Conclusions: Low burn center density (<0.4 centers per one million population) was associated with longer hospital stay, whereas no higher limit was determined.

Thermal or burn injury results in profound metabolic changes in the body. This can contribute to muscle atrophy, bone loss, as well as suppression of the immune system. While the mechanisms that underlie this hypermetabolic response remain unclear, patients with burn injury often have low circulating levels of vitamin D. Vitamin D has been shown to regulate bone formation as well as regulate muscle function. We sought to clarify the effects of vitamin D administration on skeletal muscle function following thermal injury using a mouse model. We found that thermal injury resulted in decreased vitamin D levels as well as decreased bone mineral density. Branched chain amino acid (BCAA)s levels were also significantly enhanced in the serum following burn injury. Vitamin D administration reversed the decrease in bone marrow-derived mesenchymal stem cell (BM-MSC)s observed post burn injury. Interestingly, vitamin D administration also resulted in increased tricarboxylic acid cycle (TCA) cycle metabolites in muscle which was decreased after burn conditions, enhanced the supply of alanine and glutamine in the blood which could contribute to gluconeogenesis and wound healing. Therefore, vitamin D supplementation after burn injury may have effects not only in bone metabolism, but may affect substrate metabolism in other organs/tissues.