Evaluation of Novel Classification of Heat-Related

The Japanese Association for Acute Medicine Committee recently proposed a novel 51 classification system for the severity of heat-related illnesses. The illnesses are simply classified into 52 three stages based on symptoms and management or treatment. Stages I, II, and III broadly 53 correspond to heat cramp and syncope, heat exhaustion, and heat stroke, respectively. Our objective 54 was to examine whether this novel severity classification is useful in the diagnosis by healthcare 55 professionals of patients with severe heat-related illness and organ failure. A nationwide 56 surveillance study of heat-related illnesses was conducted between June 1 and September 30, 2012, 57 at emergency departments in Japan. Among the 2130 patients who attended 102 emergency 58 departments, the severity of their heat-related illness was recorded for 1799 patients, who were 59 included in this study. In the patients with heat cramp and syncope or heat exhaustion (but not heat 60 stroke), the blood test data (alanine aminotransferase, creatinine, blood urea nitrogen, and platelet 61 counts) for those classified as stage III were significantly higher than those of patients classified as 62 stage I or II. There were no deaths among the patients classified as stage I. This novel classification 63 may avoid underestimating the severity of heat-related illness. 64