Rate, characteristics, and factors associated with high emergency department utilization

Patients with high emergency department (ED) utilization, also called “frequent visitors” (FV) account for a disproportionate number of ED visits [1, 2]. Patients with high ED utilization are a well-studied group in the literature [1‐17]. The definition of high ED utilization is debatable, ranging from 2 to more than 12 visits per year [2]. Contrary to popular belief, FV are more likely to be admitted and more likely to die in the ED, suggesting that FV are generally sicker than infrequent visitors [1, 2, 7]. FV represent severe psychosocial and medical vulnerability [5] and they are often heavy users of other health and social services [18].

The existing research on high ED utilization has raised doubts about the homogeneity of the FV [15, 19, 20]. Although FV are known to be a vulnerable population with a poor health status [14], the opposite may be true for the highest frequency visitors. Highly frequent visitors (HFV), defined as patients with 20 or more visits per year, were found to be less ill or injured than patients with single visits [15]. Attention to differences among the subgroups of FV and HFV is necessary in order to plan more effective interventions [20].

A retrospective, descriptive, correlational study was performed in two ED locations in the Netherlands: a level one ED in an inner-city trauma centre and a level three ED in a hospital located in a small city. High ED utilization was defined according to thresholds developed by Doupe et al. [6]: patients with 7 to 17 visits in 2012 were considered to be FV and those with 18 or more visits in 2012 were considered to be HFV.

Variables collected from the hospitals’ database were based on previous research regarding high ED utilization and included age [2, 12, 21], sex [21], arrival time, arrival transport mode (ambulance or not) [21], referral source (self-referred or non-self-referred), chief complaint [3, 10, 13, 16], triage level [2, 17], and visit outcome (admission, leaving without being seen by a doctor (LWBS), or death at the ED) [3, 10, 21]. Arrival time was categorized in three shifts: day shift (7.30 to 15.29 h), evening shift (15.30 to 22.59 h), and night shift (23.00 to 7.29 h). Chief complaints were identified from the triage notes for each visit. Chief complaints occurring at least 500 times per year were categorized as such, while chief complaints occurring less than 500 times were categorized as ‘Other’. Triage levels were assigned according to the 5-level Manchester Triage System, where: 1. immediate, 2. very urgent, 3. urgent, 4. standard, and 5. non-urgent [22]. In the analysis, triage levels were combined because of small numbers of patients with levels 1 and 5, to immediate/very urgent, urgent, and standard/non-urgent. Institutional review board exemption was granted.

During the 1-year study period, 71,565 consultations were registered at the two EDs, of which 50,155 were at the level one ED and 21,410 at the level three ED. These visits were paid by 51,272 different individuals. Of these 51,272 patients, 38,959 patients visited the ED a single time during the study period.

Since no univocal definition of high ED utilization exists in the literature [2], we used the thresholds recently developed by Doupe et al. [6]. They suggested that patient characteristics changed meaningfully at a breakpoint of 7 ED visits per year, thereby providing an objective threshold [6].

We assessed 244 individual FV and HFV (244 of 51,272 = 0.5% of total ED patients in one year), who presented to the two EDs on 2,338 occasions (2,338 of 71,565 = 3.3% of total ED consultations in one year). FV and HFV together in this study are a low percentage (0.5%) compared to another study using the same thresholds, where FV composed 2.1% of users and 9.9% of ED visits, whereas HFV composed 0.2% and 3.6% of users and visits, respectively [6]. It is possible that the strong primary care network in the Netherlands prevents part of the ED visits. Since practically all Dutch citizens have a general practitioner (GP) and GP services are available 24/7, patients may present to their GP instead of at the ED.

FV were significantly older than patients with single visits (47.5 vs. 39.0 years), but HFV were not. Comparing our findings with other studies is difficult: we found a study indicating that the common FV is 35 years of age [10], as well as a study claiming that as individuals get older, the risk of high ED utilization increases slightly [12]. In our study, FV were equally likely to be male or female. Results in the existing literature are equivocal; in some studies, women were disproportionately associated with high ED utilization [1, 2, 24] but the contrary has also been observed [6, 8, 11]. Besides age and gender, literature also shows some variation in presenting complaints observed by study site. Coinciding with our findings, abdominal complaints [10], shortness of breath [4, 9, 21], and mental illness [1, 5, 7, 21] tend to be the most common. Psychiatric morbidity has been found to be a significant predictor of high ED utilization [1, 5, 6, 8, 9, 13, 21]. In our study, the odds of being a FV or a HFV (versus a patient with one ED visit) was about 3- to 7-fold greater for patients attending with a psychiatric problem as the chief complaint.

In other studies, most frequent visits occurred during the evening or night shifts [3, 10]. In our study, most of the FV and HFV arrived during the day or evening shift. However, when corrected for other variables, arriving during the night shift was indicative for high ED utilization. Frequent ED use during so called off-hours is sometimes thought to be indicative of inadequate primary care [10]; however, in the Netherlands most people are registered with a local GP and out-of-hours GP cooperatives are available 24/7.

Although heterogeneity is assumed amongst the subgroups of FV and HFV, in our study, HFV were not very different from FV: they presented with the same problems and both were less likely to be self-referred compared with single visit patients. We found differences mainly in admission rates and ambulance-use; HFV were more often brought in by ambulance but less often admitted for further analysis. However, the validity of our conclusions regarding the HFV, being a very small group of patients (n = 12), may be unreliable and differences between FV and HFV, and between HFV and patients with a single visit should be further examined using a larger sample of HFV.

Most studies indicate that patients with high ED utilization are usually sick patients with chronic illness associated with high admission rates [1, 2, 7]. To corroborate this, our FV and HFV were less often assigned to the non-urgent or standard triage level than patients with single visits, and they were less likely to be self-referrals and FV had higher admission rates compared to patients with single visits. These findings suggest that FV present with more alarming symptoms. We recommend building alerts into the ED information system, drawing attention of the treating physician when a patient presents to the ED for the seventh time within a year. If hospital admission is not indicated for that particular patient, at least an appointment at the outpatient clinic should be considered.

Based on this two-ED study, in the Netherlands high ED utilization seems to be less of a problem than outlined in international literature. No major differences were found between FV and HFV. Both presented with shortness of breath, abdominal pain, urinary tract problems, or psychiatric disorders more often compared to patients with single ED visits. FV were more likely to be admitted than patients with single visits. Our study supports the notion that most patients with high ED utilization visit the ED for significant medical problems.