Heat stroke management during the COVID-19 pandemic: Recommendations from the experts in Japan (2nd edition).

Both coronavirus disease 2019 (COVID-19) and heat stroke have symptoms of fever or hyperthermia and the difficulty in distinguishing them could lead to a strain on emergency medical care. To mitigate the potential confusion that could arise from actions for preventing both COVID-19 spread and heat stroke, particularly in the context of record-breaking summer season temperatures, this work offers new knowledge and evidence that address concerns regarding indoor ventilation and indoor temperatures, mask wearing and heat stroke risk, and the isolation of older adults. Specifically, the current work is the second edition to the previously published guidance for handling heat stroke during the COVID-19 pandemic, prepared by the "Working group on heat stroke medical care during the COVID-19 epidemic," composed of members from four organizations in different medical and related fields. The group was established by the Japanese Association for Acute Medicine Heatstroke and Hypothermia Surveillance Committee. This second edition includes new knowledge, and conventional evidence gleaned from a primary selection of 60 articles from MEDLINE, one article from Cochrane, 13 articles from Ichushi, and a secondary/final selection of 56 articles. This work summarizes the contents that have been clarified in the prevention and treatment of infectious diseases and heat stroke to provide guidance for the prevention, diagnosis, and treatment of heat stroke during the COVID-19 pandemic.

Current status of active cooling, deep body temperature measurement, and face mask wearing in heat stroke and heat exhaustion patients in Japan: a nationwide observational study based on the Heatstroke STUDY 2020 and 2021.

Aim: The study aimed to determine the current status of face mask use, deep body temperature measurement, and active cooling in patients suffering from heat stroke and heat exhaustion in Japan. Methods: This was a prospective, observational, multicenter study using data from the Heatstroke STUDY 2020-2021, a nationwide periodical registry of heat stroke and heat exhaustion patients. Based on the Bouchama heatstroke criteria, we classified the patients into two groups: severe and mild-to-moderate. We compared the outcomes between the two groups and reclassified them into two subgroups according to the severity of the illness, deep body temperature measurements, and face mask use. Cramer's V was used to determine the effect sizes for a comparison between groups. Results: Almost all patients in this study were categorized as having degree III based on the Japanese Association for Acute Medicine heatstroke criteria (JAAM-HS). However, the severe group was significantly worse than the mild-to-moderate group in outcomes like in-hospital death and modified Rankin Scale scores, when discharged. Heat strokes had significantly higher rates of active cooling and lower mortality rates than heat stroke-like illnesses. Patients using face masks often use them during labor, sports, and other exertions, had less severe conditions, and were less likely to be young male individuals. Conclusions: It is suggested that severe cases require a more detailed classification of degree III in the JAAM-HS criteria, and not measuring deep body temperature could have been a factor in the nonperformance of active cooling and worse outcomes.

A prehospital risk assessment tool predicts clinical outcomes in hospitalized patients with heat-related illness: a Japanese nationwide prospective observational study.

We previously developed a risk assessment tool to predict outcomes after heat-related illness (J-ERATO score), which consists of six binary prehospital vital signs. We aimed to evaluate the ability of the score to predict clinical outcomes for hospitalized patients with heat-related illnesses. In a nationwide, prospective, observational study, adult patients hospitalized for heat-related illnesses were registered. A binary logistic regression model and receiver operating characteristic (ROC) curve analysis were used to assess the relationship between the J-ERATO and survival at hospital discharge as a primary outcome. Among eligible patients, 1244 (93.0%) survived to hospital discharge. Multivariable logistic regression analysis revealed that the J-ERATO was an independent predictor for survival to discharge (adjusted odds ratio [OR] 0.47; 95% confidence interval [CI] 0.37-0.59) and occurrence of disseminated intravascular coagulation (DIC) on day 1 (adjusted OR 2.07; 95% CI 1.73-2.49). ROC analyses revealed an optimal J-ERATO cut-off of 5 for prediction of mortality at discharge (area under the curve [AUC] 0.742; 95% CI 0.691-0.787) and DIC development on day 1 (AUC 0.723; 95% CI 0.684-0.758). The J-ERATO obtained before transportation could be helpful in predicting the severity and mortality of hospitalized patients with heat-related illnesses.

Sequential organ failure assessment score as a predictor of the outcomes of patients hospitalized for classical or exertional heatstroke.

Heatstroke is a life-threatening event that affects people worldwide. Currently, there are no established tools to predict the outcomes of heatstroke. Although the Sequential Organ Failure Assessment (SOFA) score is a promising tool for judging the severity of critically ill patients. Therefore, in this study, we investigated whether the SOFA score could predict the outcome of patients hospitalized with severe heatstroke, including the classical and exertional types, by using data from a Japanese nationwide multicenter observational registry. We performed retrospective subanalyses of the Japanese Association for Acute Medicine heatstroke registry, 2019. Adults with a SOFA score ≥ 1 hospitalized for heatstroke were analyzed. We analyzed data for 225 patients. Univariate and multivariable analyses showed a significant difference in the SOFA score between non-survivors and survivors in classical and exertional heatstroke cases. The area under the receiver operating characteristic curve were 0.863 (classical) and 0.979 (exertional). The sensitivity and specificity of SOFA scores were 50.0% and 97.5% (classical), 66.7% and 97.5% (exertional), respectively, at a cutoff of 12.5, and 35.0% and 98.8% (classical), 33.3% and 100.0% (exertional), respectively, at a cutoff of 13.5. This study revealed that the SOFA score may predict mortality in patients with heatstroke and might be useful for assessing prognosis.

Difference between 5A score and the HOPE score.

Recently, a letter to the editor was published to comment on the 5A score which is the prediction model for accidental hypothermia patients comparing the HOPE score. In this letter, we responded to the comments to clarify the difference between the 5A score and the HOPE score.

External validation of 5A score model for predicting in-hospital mortality among the accidental hypothermia patients: JAAM-Hypothermia study 2018-2019 secondary analysis.

BACKGROUND: The 5A score including five components "Age, Activities of daily living, Arrest, Acidemia and Albumin" was developed as an easy-to-use screening tool for predicting in-hospital mortality among patients with accidental hypothermia. However, the external validity of the 5A score has not yet been evaluated. We aimed to perform an external validation of the 5A score model. METHOD: This secondary analysis of the multicenter, prospective cohort Japanese Association for Acute Medicine-Hypothermia Study (2018-2019), which was conducted at 87 and 89 institutions throughout Japan, collected data from December 2018 to February 2019 and from December 2019 to February 2020. Adult accidental hypothermia patients whose body temperature was 35 °C or less were included in this analysis. The probability of in-hospital mortality was calculated using a logistic regression model of the 5A score. The albumin was not recorded in this database; thus, it was imputed by estimation. Predictions were compared with actual observations to evaluate the calibration of the model. Furthermore, decision-curve analysis was used to evaluate the clinical usefulness. RESULTS: Of the 1363 patients registered in the database, data of 1139 accidental hypothermia patients were included for analysis. The median [interquartile range] age was 79 [68-87] years, and there were 625 men (54.9%) in the study cohort. The predicted probability and actual observation by risk groups produced the following results: low 7% (5.4-8.6), mild 19.1% (17.4-20.8), moderate 33.2% (29.9-36.5), and high 61.9% (55.9-67.9) predicted risks, and the low 12.4% (60/483), mild 17.7% (59/334), moderate 32.6% (63/193), and high 69% (89/129) observed mortality. These results indicated that the model was well calibrated. Decision-curve analysis visually indicated the clinical utility of the 5A score model. CONCLUSION: This study indicated that the 5A score model using estimated albumin value has external validity in a completely different dataset from that used for the 5A model development. The 5A score is potentially helpful to predict the mortality risk and may be one of the valuable information for discussing the treatment strategy with patients and their family members.

Extracorporeal cardiopulmonary resuscitation in adult patients with out-of-hospital cardiac arrest: a retrospective large cohort multicenter study in Japan.

BACKGROUND: The prevalence of extracorporeal cardiopulmonary resuscitation (ECPR) in patients with out-of-hospital cardiac arrest (OHCA) has been increasing rapidly worldwide. However, guidelines or clinical studies do not provide sufficient data on ECPR practice. The aim of this study was to provide real-world data on ECPR for patients with OHCA, including details of complications. METHODS: We did a retrospective database analysis of observational multicenter cohort study in Japan. Adult patients with OHCA of presumed cardiac etiology who received ECPR between 2013 and 2018 were included. The primary outcome was favorable neurological outcome at hospital discharge, defined as a cerebral performance category of 1 or 2. RESULTS: A total of 1644 patients with OHCA were included in this study. The patient age was 18-93 years (median: 60 years). Shockable rhythm in the initial cardiac rhythm at the scene was 69.4%. The median estimated low flow time was 55 min (interquartile range: 45-66 min). Favorable neurological outcome at hospital discharge was observed in 14.1% of patients, and the rate of survival to hospital discharge was 27.2%. The proportions of favorable neurological outcome at hospital discharge in terms of shockable rhythm, pulseless electrical activity, and asystole were 16.7%, 9.2%, and 3.9%, respectively. Complications were observed during ECPR in 32.7% of patients, and the most common complication was bleeding, with the rates of cannulation site bleeding and other types of hemorrhage at 16.4% and 8.5%, respectively. CONCLUSIONS: In this large cohort, data on the ECPR of 1644 patients with OHCA show that the proportion of favorable neurological outcomes at hospital discharge was 14.1%, survival rate at hospital discharge was 27.2%, and complications were observed during ECPR in 32.7%.

Serum D-dimer level as a predictor of neurological functional prognosis in cases of head injuries caused by road traffic accidents.

BACKGROUND: The number of traffic fatalities is declining in Japan; however, a large proportion of head injuries are still attributable to traffic accidents. Severe head trauma may cause progressive and devastating coagulopathy owing to exacerbated coagulation and fibrinolysis, which results in massive bleeding and poor patient outcomes. D-dimer is a fibrinolytic marker, which remarkably increases in severe coagulopathy due to the exacerbated fibrinolytic system. Because the degree of coagulopathy is associated with patient outcomes, the D-dimer level is a useful prognostic predictor in patients with head trauma. However, the usefulness of D-dimer in cases of head trauma caused by road traffic accidents remains inadequately explored. In this study, we investigated the relationship between D-dimer levels and outcomes in head injuries caused by traffic accidents. METHODS: We extracted data on traffic injuries from Japan Neuro-Trauma Data Bank Project 2015, which is a prospective multicenter registry of head injuries. The analysis included 335 individuals with no missing data. The outcome variable was the score of the Glasgow Outcome Scale (GOS), a neurological outcome index. The participants were categorized into the favorable outcome (GOS score ≥ 4) and poor outcome (GOS score ≤ 3) groups. The serum D-dimer levels at the time of admission were divided into four categories at the quartiles, and the reference category was less than the first quartile (< 17.4 µg/mL). We performed a logistic regression analysis with GOS as the dependent variable and D-dimer as a predictor and performed a multivariate analysis that was adjusted for 10 physiological parameters. RESULTS: In the univariate analysis, all groups with serum D-dimer values ≥ 17.4 µg/dL showed significantly poorer outcomes than those of the reference group. In the multivariate analysis, after adjusting for other factors, D-dimer levels ≥ 89.3 µg/dL were an independent predictor of poor outcome. CONCLUSION: After adjusting for physiological parameters, high serum D-dimer levels can be an independent factor for predicting neurological prognosis in head trauma caused by road traffic accidents.

Influence of the coronavirus disease 2019 (COVID-19) pandemic on the incidence of heat stroke and heat exhaustion in Japan: a nationwide observational study based on the Heatstroke STUDY 2019 (without COVID-19) and 2020 (with COVID-19).

AIM: To assess heat stroke and heat exhaustion occurrence and response during the coronavirus disease 2019 pandemic in Japan. METHODS: This retrospective, multicenter, registry-based study describes and compares the characteristics of patients between the months of July and September in 2019 and 2020. Factors affecting heat stroke and heat exhaustion were statistically analyzed. Cramér's V was calculated to determine the effect size for group comparisons. We also investigated the prevalence of mask wearing and details of different cooling methods. RESULTS: No significant differences were observed between 2019 and 2020. In both years, in-hospital mortality rates just exceeded 8%. Individuals >65 years old comprised 50% of cases and non-exertional onset (office work and everyday life) comprised 60%-70%, respectively. The recommendations from the Working Group on Heat Stroke Medicine given during the coronavirus disease pandemic in 2019 had a significant impact on the choice of cooling methods. The percentage of cases, for which intravascular temperature management was performed and cooling blankets were used increased, whereas the percentage of cases in which evaporative plus convective cooling was performed decreased. A total of 49 cases of heat stroke in mask wearing were reported. CONCLUSION: Epidemiological assessments of heat stroke and heat exhaustion did not reveal significant changes between 2019 and 2020. The findings suggest that awareness campaigns regarding heat stroke prevention among the elderly in daily life should be continued in the coronavirus disease 2019 pandemic. In the future, it is also necessary to validate the recommendations of the Working Group on Heatstroke Medicine.

Association between active cooling and lower mortality among patients with heat stroke and heat exhaustion.

Body cooling is recommended for patients with heat stroke and heat exhaustion. However, differences in the outcomes of patients who do or do not receive active cooling therapy have not been determined. The best available evidence supporting active cooling is based on a case series without comparison groups; thus, the effectiveness of this method in improving patient prognoses cannot be appropriately quantified. Therefore, we compared the outcomes of heat stroke patients receiving active cooling with those of patients receiving rehydration-only therapy. This prospective observational multicenter registry-based study of heat stroke and heat exhaustion patients was conducted in Japan from 2010 to 2019. The patients were stratified into the "severe" group or the "mild-to-moderate" group, per clinical findings on admission. After conducting multivariate logistic regression analyses, we compared the prognoses between patients who received "active cooling + rehydration" and patients who received "rehydration only," with in-hospital death as the endpoint. Sex, age, onset situation (i.e., exertional or non-exertional), core body temperature, liver damage, renal dysfunction, and disseminated intravascular coagulation were considered potential covariates. Among those who received active cooling and rehydration-only therapy, the in-hospital mortality rates were 21.5% and 35.5%, respectively, for severe patients (n = 231) and 3.9% and 5.7%, respectively, for mild-to-moderate patients (n = 578). Rehydration-only therapy was associated with a higher in-hospital mortality in patients with severe heat illness (adjusted odds ratio [aOR], 3.29; 95% confidence interval [CI], 1.21-8.90), whereas the cooling methods were not associated with lower in-hospital mortality in patients with mild-to-moderate heat illness (aOR, 2.22; 95% CI, 0.92-5.84). Active cooling was associated with lower in-hospital mortality only in the severe group. Our results indicated that active cooling should be recommended as an adjunct to rehydration-only therapy for patients with severe heat illness.

Accidental hypothermia: characteristics, outcomes, and prognostic factors-A nationwide observational study in Japan (Hypothermia study 2018 and 2019).

AIM: This study describes the clinical characteristics and outcomes as well as the prognostic factors of patients with accidental hypothermia (AH) using Japan's nationwide registry data. METHODS: The Hypothermia study 2018 and 2019, which included patients aged 18 years or older with a body temperature of 35°C or less, was a multicenter registry conducted at 87 and 89 institutions throughout Japan, with data collected from December 2018 to February 2019 and December 2019 to February 2020, respectively. RESULTS: In total, 1363 patients were enrolled in the registry, of which 1194 were analyzed in this study. The median (interquartile range) age was 79 (68-87) years, and the median (interquartile range) body temperature at the emergency department was 30.8°C (28.4-33.6°C). Forty-three percent of patients with AH had a mild condition, 35.2% moderate, and 21.9% severe. AH occurred in an indoor setting in 73.4% and was caused by acute medical illness in 49.3% of patients. A total of 101 (8.5%) patients suffered from cardiopulmonary arrest on arrival at the hospital. The overall 30-day mortality rate was 24.5%, the median (interquartile range) intensive care unit stay was 4 (2-7) days, and the median (interquartile range) hospital stay was 13 (4-27) days. In the multivariable logistic analysis, the prognostic factors were age (≥75 years old), male, activities of daily living (needing total assistance), cause of AH (trauma, alcohol), Glasgow Coma Scale score, and potassium level (>5.5 mEq/L). CONCLUSION: The mortality rate of AH was 24.5% in Japan. The prognostic factors developed in this study may be useful for the early prediction, prevention, and awareness of severe AH.

Association between frailty and mortality among patients with accidental hypothermia: a nationwide observational study in Japan.

BACKGROUND: Frailty has been associated with a risk of adverse outcomes, and mortality in patients with various conditions. However, there have been few studies on whether or not frailty is associated with mortality in patients with accidental hypothermia (AH). In this study, we aim to determine this association in patients with AH using Japan's nationwide registry data. METHODS: The data from the Hypothermia STUDY 2018&19, which included patients of ≥18 years of age with a body temperature of ≤35 °C, were obtained from a multicenter registry for AH conducted at 120 institutions throughout Japan, collected from December 2018 to February 2019 and December 2019 to February 2020. The clinical frailty scale (CFS) score was used to determine the presence and degree of frailty. The primary outcome was the comparison of mortality between the frail and non-frail patient groups. RESULTS: In total, 1363 patients were included in the study, of which 920 were eligible for the analysis. The 920 patients were divided into the frail patient group (N = 221) and non-frail patient group (N = 699). After 30-days of hospitalization, 32.6% of frail patients and 20.6% of non-frail patients had died (p < 0.001). Frail patients had a significantly higher risk of 90-day mortality (Hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.25-2.17; p < 0.001). Based on the Cox proportional hazards analysis using multiple imputation, after adjustment for age, potassium level, lactate level, pH value, sex, CPK level, heart rate, platelet count, location of hypothermia incidence, and rate of tracheal intubation, the HR was 1.69 (95% CI, 1.25-2.29; p < 0.001). CONCLUSIONS: This study showed that frailty was associated with mortality in patients with AH. Preventive interventions for frailty may help to avoid death caused by AH.

Machine learning-based mortality prediction model for heat-related illness.

In this study, we aimed to develop and validate a machine learning-based mortality prediction model for hospitalized heat-related illness patients. After 2393 hospitalized patients were extracted from a multicentered heat-related illness registry in Japan, subjects were divided into the training set for development (n = 1516, data from 2014, 2017-2019) and the test set (n = 877, data from 2020) for validation. Twenty-four variables including characteristics of patients, vital signs, and laboratory test data at hospital arrival were trained as predictor features for machine learning. The outcome was death during hospital stay. In validation, the developed machine learning models (logistic regression, support vector machine, random forest, XGBoost) demonstrated favorable performance for outcome prediction with significantly increased values of the area under the precision-recall curve (AUPR) of 0.415 [95% confidence interval (CI) 0.336-0.494], 0.395 [CI 0.318-0.472], 0.426 [CI 0.346-0.506], and 0.528 [CI 0.442-0.614], respectively, compared to that of the conventional acute physiology and chronic health evaluation (APACHE)-II score of 0.287 [CI 0.222-0.351] as a reference standard. The area under the receiver operating characteristic curve (AUROC) values were also high over 0.92 in all models, although there were no statistical differences compared to APACHE-II. This is the first demonstration of the potential of machine learning-based mortality prediction models for heat-related illnesses.

Variability of extracorporeal cardiopulmonary resuscitation practice in patients with out-of-hospital cardiac arrest from the emergency department to intensive care unit in Japan.

AIM: A lack of known guidelines for the provision of extracorporeal cardiopulmonary resuscitation (ECPR) to patients with out-of-hospital cardiac arrest (OHCA) has led to variability in practice between hospitals even in the same country. Because variability in ECPR practice has not been completely examined, we aimed to describe the variability in ECPR practice in patients with OHCA from the emergency department (ED) to the intensive care units (ICU). METHODS: An anonymous online questionnaire to examine variability in ECPR practice was completed in January 2020 by 36 medical institutions who participated in the SAVE-J II study. Institutional demographics, inclusion and exclusion criteria, initial resuscitation management, extracorporeal membrane oxygenation (ECMO) initiation, initial ECMO management, intra-aortic balloon pumping/endotracheal intubation/management during coronary angiography, and computed tomography criteria were recorded. RESULTS: We received responses from all 36 institutions. Four institutions (11.1%) had a hybrid emergency room. Cardiovascular surgery was always involved throughout the entire ECMO process in only 14.7% of institutions; 60% of institutions had formal inclusion criteria and 50% had formal exclusion criteria. In two-thirds of institutions, emergency physicians carried out cannulation. Catheterization room was the leading location of cannulation (48.6%) followed by ED (31.4%). The presence of formal exclusion criteria significantly increased with increasing ECPR volume (P for trend <0.001). Intra-aortic balloon pumping was routinely initiated in only 25% of institutions. Computed tomography was routinely carried out before coronary angiography in 25% of institutions. CONCLUSIONS: We described the variability in ECPR practice in patients with OHCA from the ED to the ICU.

Accidental hypothermia: Factors related to a prolonged hospital stay - A nationwide observational study in Japan.

BACKGROUND: The incidence of accidental hypothermia (AH) is low, and the length of hospital stay in patients with AH remains poorly understood. The present study explored which factors were related to prolonged hospitalization among patients with AH using Japan's nationwide registry data. METHODS: The data from the Hypothermia STUDY 2018, which included patients ≥18 years old with a body temperature ≤ 35 °C, were obtained from a multicenter registry for AH conducted at 89 institutions throughout Japan, collected from December 1, 2018, to February 28, 2019. The patients were divided into a "short-stay patients" group (within 7 days) and "long-stay patients" group (more than 7 days). A logistic regression analysis after multiple imputation was performed to obtain odds ratios (ORs) for prolonged hospitalization with age, frailty, location, causes underlying the hypothermia, temperature, pH, potassium level, and disseminated intravascular coagulation (DIC) score as independent variables. RESULTS: In total, 656 patients were included in the study, of which 362 were eligible for the analysis. The median length of hospital stay was 17 days. Of the 362 patients, 265 (73.2%) stayed in the hospital for more than 7 days. The factors associated with prolonged hospitalization were frailty (OR, 2.11; 95% confidence interval [CI], 1.09-4.10; p = 0.027), the occurrence of indoor (OR, 3.20; 95% CI, 1.58-6.46; p = 0.001), alcohol intoxication (OR, 0.17; 95% CI, 0.05-0.56; p = 0.004), pH (OR, 0.07; 95% CI, 0.01-0.76; p = 0.029), potassium level (OR, 1.36; 95% CI, 1.00-1.85; p = 0.048), and DIC score (OR, 1.54; 95% CI, 1.13-2.10; p = 0.006). CONCLUSIONS: Frailty, indoor situation, alcohol intoxication, pH value, potassium level, and DIC score were factors contributing to prolonged hospitalization in patients with AH. Preventing frailty may help reduce the length of hospital stay in patients with AH. In addition, measuring the pH value and potassium level by an arterial blood gas analysis at the ED is recommended for the early evaluation of AH.

Safety and efficacy of cold-water immersion in the treatment of older patients with heat stroke: a case series.

BACKGROUND: Heat stroke treatment focuses on rapid cooling because symptom severity correlates with the duration of hyperthermia (i.e., time during which the core body temperature is sustained above the critical threshold). Several reports have revealed that cold-water immersion is a safe and appropriate therapy for exertional heat stroke in young, otherwise healthy patients. However, few reports have assessed cold-water immersion in older patients. We document three cases of cold-water immersion in older heat stroke patients and evaluate its safety and efficacy. CASE PRESENTATION: Three older patients with severe heat stroke were treated with cold-water immersion. Core body temperatures decreased rapidly, and no complications occurred during the treatment. CONCLUSION: Cold-water immersion can achieve rapid cooling and is effective in treating heat stroke. With special precautions, it can be performed safely for older patients. Further investigation is warranted to establish appropriate cooling methods in older adults.

Clinical characteristics, prognostic factors, and outcomes of heat-related illness (Heatstroke Study 2017-2018).

AIM: Heat-related illness is common, but its epidemiology and pathological mechanism remain unclear. The aim of this study was to report current clinical characteristics, prognostic factors, and outcomes of heat-related illness in Japan. METHODS: We undertook a prospective multicenter observational study in Japan. Only hospitalized patients with heat-related illness were enrolled from 1 July to 30 September 2017 and 1 July to 30 September 2018. RESULTS: A total of 763 patients were enrolled in the study. Median age was 68 years (interquartile range, 49-82 years) and median body temperature on admission was 38.2°C (interquartile range, 36.8-39.8°C). Non-exertional cause was 56.9% and exertional cause was 40.0%. The hospital mortality was 4.6%. The median Japanese Association for Acute Medicine disseminated intravascular coagulation (JAAM DIC), Sequential Organ Failure Assessment (SOFA), and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores on admission were 1 (0-2), 4 (2-6), and 13 (8-22), respectively. To predict hospital mortality, areas under the receiver operating characteristic curves were 0.776 (JAAM DIC score), 0.825 (SOFA), and 0.878 (APACHE II). There were 632 cases defined as heatstroke by JAAM heat-related illness criteria, 73 cases diagnosed as having DIC. A total of 16.6% patients had poor neurological outcome (modified Rankin Scale ≥ 4) at hospital discharge. In the multivariate analysis, Glasgow Coma Scale and platelets were independent predictors of mortality. Type of heatstroke, Glasgow Coma Scale, and platelets were independent predictors of poor neurological outcome. Body temperature was not associated with mortality or poor neurological outcome. CONCLUSIONS: In this study, hospital mortality of heat-related illness was <5%, one-sixth of the patients had poor neurological outcome. The APACHE II, SOFA, and JAAM DIC scores predicted hospital mortality. Body temperature was not associated with mortality or poor neurological outcome.