Association between emergency department length of stay and adverse perioperative outcomes in emergency surgery: a cohort study in two Colombian University hospitals

Emergency surgery (ES) is associated with significantly higher morbidity and mortality when compared with elective procedures [1‐4]. Factors that influence outcomes after ES include patient’s previous clinical condition [5, 6], the availability of health care resources [7], and the timeliness of administrative and organizational processes [8].

In developing countries, ES represents a relatively high fraction of the total surgical procedures [9]. International comparisons indicate that in countries with lower scores in the United Nations human development index, mortality from ES is 2 to 3 times higher, compared to the counterparts [10]. In recent years, as a result of the distribution and access to health services, hospitals in Colombia have experienced increasing demands and overcrowding in emergency departments (ED) [11]. A large international study reported that ES represented 11% of all non-cardiac surgeries, which contrasts with data from Colombian centers that participated in such study, where a significantly higher ES rate (43%) was found and associated with a 3.5-fold increase in 30-day mortality [3].

Although many predictors of postoperative morbidity and mortality are not modifiable, there still certain opportunities for improvement in the process of patient care that could alter these results. The ED length of stay (LOS), a potentially modifiable factor, is linked with worse patient outcomes in specific populations. A prolonged ED-LOS has been associated with an increase in 30-day mortality in critically ill patients [12, 13], and patients with traumatic injuries [14]. These patients require highly specialized care, often protocolized and administered on a one-by-one basis, which is difficult to provide for the frequently busy ED staff [12, 14]. However, there is little understanding of the relationship between ED LOS and outcomes in patients admitted for ES, particularly in developing countries.

Study aims were to determine if ED LOS was associated with the incidence of adverse perioperative outcomes (APO) and whether this association varied across the patient’s risk categories in patients undergoing ES.

Overall, our analyses include 1487 patients (see Fig. 1), 2/3 from representative samples, with center A providing 2/3 of the population. Table 1 shows patient demographics and preoperative characteristics using the representative samples of both centers. Although center A admitted more often complex patients (with prior medical conditions or cumulated risk factors, receiving more frequent assessments and diagnostic workup), ED-LOS were similar among centers (median time 24.2 and 24.8 h, p = 0.965).

Using 48 h as working cut-off, ED-LOS had a positive relationship with age, comorbidities and 30-day mortality risk factors present on admission (Table 2). ED-LOS was also associated with having more frequent medical assessments or diagnostic workup in the ED, performing abdominal surgery and the length of the procedure itself. Of note, 141 (24.2%) of patients who stayed in the ED > 48 h had no 30-day mortality risk factors.

Figure 2 shows the association between the number of risk factors and APO by having or not prolonged ED-LOS (> 48 h). Although ED-LOS seems to influence outcomes, the number of risk factors gradually attenuates its effect (from higher among those with no factors, to smaller for those with multiple factors, p < 0.001 for interaction). Univariate analysis comparing characteristics of patients who had outcome events with those who did not is shown in Table 3. As expected, patients with APO were older and had more often comorbidities and 30-day mortality risk factors (p < 0.01 in all cases). Importantly, patients with APO had longer duration of surgery and 27-h longer ED-LOS (median times 53.2 versus 26.1, p < 0.001).

Multivariate analysis indicated that prolonged ED-LOS (> 48 h versus ≤48 h) was independently associated with APO (aOR = 1.99, IC95% 1.13–3.51), as well as other factors: the center performing the surgery; history of renal disease; having 30-day mortality risk factors, the number of ED medical assessments, undergoing abdominal surgery and the duration of surgery (Table 4). Finally, the covariate-adjusted relationship between prolonged ED-LOS and APO significantly decreased by the number of 30-day mortality risk factors present (aORs 2.52, 0.87, 0.72 for having no, 1–2 or 3 30-day mortality risk factors, respectively). Of note, while a high ED-LOS was associated with higher risk of events, this was protective among patients with 3 or more 30-day mortality risk factors (p < 0.001 for interaction). A similar trend was observed for mortality (Fig. 3).

This study shows that in patients undergoing emergency general or orthopedic surgery, a prolonged (> 48 h) ED-LOS is associated with adverse outcomes. Importantly, the direction of this association varies with patients’ specific aspects such as the number of risk factors for 30-day mortality upon admission to the ED. Patients with no risk factors whose operation began after 48 h of admission were at an elevated risk of perioperative adverse outcome in contrast to patients with three or more risk factors in whom this wait seems to be protective.

The time elapsed to take the patient to surgery can be misleading, subject to interpretation and may be obscured by confounding factors. The field lacks of a standard definition for it, as some authors propose to start measuring from admission to ED, while others from the decision to operate. Furthermore, a variety of medical and non-medical factors can cause delays in transfer patients from the ED to an operating room. The present study suggests that ED-LOS in the more complex cases is justified, as it is used in obtaining an adequate diagnosis and in the preoperative optimization (as shown by receiving more medical assessments and diagnostic workup prior to surgery). Nevertheless, in a low-risk patient, in whom the margin of optimization is limited, prolong ED-LOS would be deleterious and rapid intervention should be prioritized.

The association between delay in surgical intervention and perioperative outcomes has been controversial. In specific areas of emergency general surgery such as perforated peptic ulcer [17] and gastrointestinal perforation [18], times before surgery were reported as a critical determinant of survival. McIsaac et al. showed in a recent propensity matched score analysis that delayed operating room access for ES was also associated with higher in-hospital mortality, longer hospital stays and higher costs. They found that system (i.e., non-medical) factors were the main reasons for delay [19]. However, they not took into account the time from admission to the decision to operate which most of the time is used for diagnostic tests and preoperative therapies in order to optimize patient’s physiologic derangements before surgery. In contrast, several other reports have refuted the association between bad outcomes and surgical delays [20, 21].

In our study, a significant proportion of patients without risk factors (24.2%) remained in the ED for a period of time greater than 48 h before being transferred to operating room. This excess ED-LOS is not explained by preoperative risk factors and therefore raises concern, making this group of patients an excellent target for quality improvement strategies. Furthermore, ED-LOS along with risk stratification should be an indicator of quality of care. Previous research exploring the causes of a prolonged ED LOS in emergent surgery has identified both medical factors (delayed diagnosis) [17] and administrative issues (physicians availability, lack of resources and organizational problems) [8, 19, 20]. We do not know exactly the causes responsible for a prolonged ED-LOS in our system, but we are aware of the need to further evaluate these factors and the specific determinants of negative outcomes. Besides, we would like to assess alternative models of patient care aiming to reduce waiting times and ED LOS [22]. In the meantime, we have implemented several changes focused on the establishment of new standards for access to operating room. Also, a prioritization system has been instituted as well as we have set a surgery room exclusively dedicated to the care of ES. Providing access to the operating room in a timely fashion for patients who need ES will require the efforts and commitment of medical, paramedical and administrative personnel, as well as clear hospital policies that optimize the use of currently available resources.

The results of this study should be read in the context of hospitals located in a middle-income country. Previous research, in general, originates from Canada, the United States and Europe, and the comparison of our results with these studies is relatively difficult due to the differences in the model of patient care between countries. Several investigations have reported international differences in access to surgical care, the ratio of emergency/elective surgeries and the mortality rates [10, 23]. In the present study the median ED-LOS was 24.6 h, with almost 40% of patients waiting for more than 48 h, well in contrast with times found in more advanced countries [17, 18, 24, 25]. This difference is even more relevant given the fact that in developing countries, ES represents a relatively high fraction of the surgical procedures [9].

There are certain limitations in our investigation that need to be highlighted. First, this is a retrospective study with the inherent limitations of this type of design. Second, the results were not discriminated according to the type of surgery; it is clear that for some specific surgical procedures such as appendectomy the surgical intervention should not be delayed for more than 6 h surgery, and also the early intervention in hip fracture is associated with improved outcomes. Finally, our study did not attempt to isolate the reasons for a prolonged ED-LOS because some possibly related variables were not available.

The results of this study suggest that in emergency abdominal and orthopedic surgery, a prolonged ED-LOS may be associated with an excess of adverse outcomes. This association, however, depends on the number of preoperative risk factors, being harmful for those at low-risk. Further research is needed to identify the causes of prolonged ED-LOS and the specific determinants of adverse perioperative outcomes.