To our knowledge, this study is a representative large–scale study describing national characteristics of ED visits by ESRD patients. A thoughtful study by Lovasik et al.  examined the use of ED among ESRD patients with Medicare. However, the population of their study was limited to the ED patients with ESRD only, and the analysis of the study was around the characterisics of hospitalization.. Our study focused on all ED adult patient visits between 2014 and 2016 in the United States, and the results were concluded from the comparison of ED visits by patients ESRD and non-ESRD status. In addition, our study also provided the medical resource utilization information of ED visits by ESRD patients, such as blood tests and medical imaging. The above information helped generate national-representative results about ED visits by ESRD patients. We also noticed another ED utilization analysis by Ronksley et al.  was under a national population scale, but they explored the emergency department use among patients with CKD, which has a different focus and interest compared to the present study.
From 2014 to 2016, there were 2,168,075 ED visits by ESRD patients in total, and the number of annual visits by those patients increased stably. Demographic factors were associated with the prevalence of ESRD in ED patients. In our study, compared to patients without ESRD, ED visits by ESRD patients were characterized to be associated with male senior patients. This same gender difference phenomenon in ESRD patients has been documented in the field of nephrology. A nationwide survey of ESRD by the Japanese Society for Dialysis Therapy revealed a higher incidence and prevalence in men than in women according to the research on gender differences in chronic kidney disease . Age is usually considered as one of the risk factors for ESRD partly because aging is associated with cardiovascular diseases. Nearly half of incident dialysis patients in the United States annually are senior citizens . It is known that the cardiovascular mortality rate in ESRD patients is 10–20 times higher than that in the general population . Therefore, the clinical care of cardiovascular diseases among ED patients with ESRD is necessary.
Accordingly, ESRD is a complex clinical condition caused by chronic kidney disease, high blood pressure, and others, and the incidence of ESRD increased sharply with age in both sexes , and ESRD patients need special and professional health care in both emergency and non-emergency cases. Diabetes and hypertension account for more than 50 % of cases of ESRD, and care of patients will increasingly depend on primary care physicians . In this study, we found that ED visits by ESRD patients were six times more likely to be from nursing homes than a private residence, and also more likely to be delivered by ambulance rides than other means. This is consistent with previous findings  receiving hemodialysis in the post-dialysis initiation period was a high-risk time for falls that among older people.
Compared to non-ESRD patients, those with ESRD had higher rates of hospital and ICU admission as well as higher revisiting times in 72 hours. The higher chance is ED revisiting, and hospital admission for the ESRD patients can be associated with the higher severity of the condition, poor outcomes of previous treatments, and high costs for this patient cohorts. Many previous studies have similar findings, for example, US Renal Data System reported that an overall rehospitalization rate for patients with ESRD was 34% within 30 days of discharge . We also noticed that ED patients with ESRD were more likely to present clinical symptoms of high body temperature, high heart rate, and low DBP than the patients without ESRD. All the above symptoms related to the adverse effect of medical/surgical treatment which was the highest reason for ESRD patients visiting ED.
Understanding the above characteristics of ED visits by ESRD patients may help the clinicians understand the patients at high risk for ED visit, hospital admission, and other health outcomes and the need for the medical resource use, thus to improve the efficiency of clinical care and reduce the high rates of hospital admission, which would benefit ESRD patients. and benefit hospitals in terms of better resource allocation and better financial allocation.
In the patient histories documented in the NHAMCS-ED data, patients are coded either having or not having ESRD status, information such as duration, treatment history were not tracked in the dataset. This information would enhance a better prediction of ESRD status among ED patients. As Iseki noted, ESRD is not a specific disease entity, but rather provides a framework for the consideration of treatment options . Understanding the relationship between ESRD and other chronic diseases would determine risk factors in utilizing ED resources for ESRD patients. Another limitation was the dataset did not provide information about patients’ health conditions. It is known that ESRD patients in ED were relatively stable for the elder age group as we found in the study. Knowing their health information would provide more predictors to the characteristics of ED visits by ESRD patients.