Emergency department patients who leave without being seen ( LWBS ) : A population-based study in Veneto region , Italy 1

Although it is commonly thought that patients who LWBS have non urgent medical problems, some studies have shown that they may actually require important medical attention on further consultation, such as hospitalization or surgery [3,4,12] and also, many patients who LWBS seek further medical care elsewhere [13]. As these patients may have important clinical outcomes and therefore require a critical treatment, the health system missed an opportunity of contact with these patients. The rate of patients who LWBS has been considered one of the most important performance indicators for EDs [6,14,15].


Introduction
Emergency departments (ED) are becoming increasingly overcrowded, leading to longer waiting times and greater patient dissatisfaction, which are associated with patients leaving the ED prematurely [1,2].
Uncompleted visits in the emergency department are a patient safety concern and the two types of uncompleted visits are patients who leave without being seen (LWBS) by a physician and patients who leave the ED Against Medical advice (AMA).
Although it is commonly thought that patients who LWBS have non urgent medical problems, some studies have shown that they may actually require important medical attention on further consultation, such as hospitalization or surgery [3,4,12] and also, many patients who LWBS seek further medical care elsewhere [13].As these patients may have important clinical outcomes and therefore require a critical treatment, the health system missed an opportunity of contact with these patients.The rate of patients who LWBS has been considered one of the most important performance indicators for EDs [6,14,15].
A number of studies from high income countries with a wellestablished primary health care system have reported a vari-Journal of Community Medicine able number of LWBS which ranges from <1% up to 20% of all ED visits [8,12,[16][17][18].

Methods
This was an observational retrospective case-control study based on administrative anonymous aggregated data using the regional ED database of Veneto Region, a 5 million inhabitants region of North-East Italy.
All patients admitted to 52 EDs of public and private hospitals, between 2011 and 2015 were included.EDs are connected within a regional hospital network constituted by: a) 7 "hub" hospitals with highly-specialized services located in the main cities, of which 2 university hospitals, b) 24 "spoke" hospitals, medium size, each serving an average population of 250,000 inhabitants, and c) 21 small local hospitals.
Age, sex, citizenship and residence were established from the ED record for each episode of care and other aspects considered were about ED access and hospital characteristic.
The code at the check-in desk triage was assigned in accordance with level of need.
In order to obtain information about which factors affects more the probability of LWBS a Chi-squared analysis on contingency tables was performed.Moreover, ORs and 95% confidence interval were calculated.

Results
Overall 9,147,415 patients attended the EDs of Veneto Region from 2011 to 2015, and the LWBS rate is 13.4‰.
Sex and age distribution of patients are shown in Table 1.The probability of self-discharge is higher for the patients aged 15-24 (OR: 1.07; CI95%: 1.05-1.09;p < 0.05) followed by subsequent group (25-44 years) took as reference due to its representativeness (25%).
Hospital admissions of newborns represent the 2% of the sample and they show an extremely contained LWBS risk (OR: 0.53; CI95%: 0.15-0.16;p < 0.05).Moreover, it is evident how advanced age is associated with a lower risk of uncompleted visits.
The majority of ED accesses was in the Local Health Unit (LHU) of patients' residence (71%) and there was a risk of LWBS lower for the ones who access to ED of the LHU of residence (11.7‰) showing how the proximity of patients' homes represents a protective factor against LWBS.
After stratifying self-discharge risk by underlying medical conditions and subsequent attribution of emergency level, it is of particular interest to notice, as expected, an association between seriousness of illness and LWBS (χ2 for trend: 29044.455;p < 0.05).
Another protective factor resulted to be the traumatic pathology as cause of access (OR: 0.82; CI95%: 0.81-0.83;p < 0.05) present in 30% of overall access.
After stratifying the sample by waiting time, 77% of patients were evaluated within 1 hour and 90% within 2 hours.It comes to light that waiting time represents a significant determinant for leaving ED.This association resulted to be significant (χ2 for trend: 161335.676;p < 0.05), highlighting how a waiting time of more than 4 hour is strongly associated with an elevated risk of LWBS (OR: 12.9; CI95%: 12.71-13.13;p < 0.05).
As shown in Table 3, an increase in ED volume of activity correlates with an increase in LWBS (χ2 for trend: 283883.120;p < 0.05).Data regarding private hospitals could explained this trend (OR: 0.62; CI95%: 0.61-0.63;p < 0.05): three private hospitals out of six included in the analysis reported less than 25,000 ED admissions per year and the other three between 25,000 and 50,000 ED admissions per year.A similar trend is followed by data regarding hospitals' role in the regional network: 5 of 7 Hub hospitals, where the highest risk for self-discharge is reported (OR: 2.02; CI95%: 1.99-2.06;p < 0.05), have a volume of access constantly greater than 75,000 admission per year.

Discussion
This study draws attention to the fact that uncompleted care pathways due to self-discharge not only affect hospital admissions [29], but also ED admission.This can be identified as a consistent indicator of quality of care in the same hospitals and risks associated with healthcare activities.
Young adults (18-39 year old) were the most likely to LWBS, as it was shown in other studies, and foreigners may be using the ED as a source of primary care, given the finding that most LWBS visits are of low acuity.
Data demonstrated that the length of waiting time was the central issue for LWBS, and justifies the high rate of hospitals with a large volume of ED activity and a consequent overcrowded environment, as widely described elsewhere [26][27][28].
This observational study suggests that patients who leave ED without been seen represent a small but important subgroup of ED patients and identifies the main risk factors for this phenomenon.It would also be beneficial to further evaluate what happen to LWBS patients in a prospective follow-up study.
In the light of a relative lack of studies and information on Italian situation this study provides useful evidence in order to sharpen up strategies and interventions against LWBS.