Association between Public Assistance and Frequent Emergency Department Visits in Urban Areas of Japan: A Case-Control Study

: Emergency department （ ED ） crowding due to frequent visitors increases medical costs and endangers the safety of patients who need prompt treatment. Although some studies have examined the social background of frequent visitors to the ED, there are few comprehensive studies of factors related to frequent ED visits in Japan. The present study examined whether public assistance status, age, and underlying conditions are associated with frequent visits to the ED. Subjects in this study were patients over 20 years of age who visited the ED of General Medicine in Showa University Hospital in Tokyo, Japan, from April 1, 2014, to March 31, 2015 （ n ＝ 6,182 ） . Information regarding sex, age, public insurance, hypertension, diabetes mellitus, dyslipidemia, chronic obstructive pulmonary disease, cancer, dysuria, bronchial asthma, and chronic kidney disease was collected using a patient database created from medical and hospital records. Based on a previous study, subjects who visited the ED four or more times were defined as frequent visitors, while those who visited the ED less than four times were considered infrequent visitors. Logistic regression analysis was performed to calculate odds ratios （ ORs ） and 95 ％ confidence intervals （ CIs ） for frequent ED visits. of public assistance significantly increased the OR for frequent visits （ 4.26, 95 ％ CI: 1.90 - 9.56 ） , even after adjusting for sex, age, and potential confounding factors （ OR: 3.89, 95 ％ CI: 1.62 - 9.35 ） . The current study found a significant association between frequent ED visits and the receipt of public assistance. outpatient physicians and welfare officers and work together with patients to address their specific medical and social vulnerabilities.