Abstract
Background
Unfavorable outcomes occur in patients with acute abdominal pain who visit the emergency department (ED). We aimed to determine the factors associated with unfavorable outcomes in patients with acute abdominal pain visiting the ED.
Methods
This retrospective cohort study was conducted from July 1, 2015 to June 30, 2016. The inclusion criterion was patients aged older than 18 years who presented to the ED with acute abdominal pain. Significant factors associated with unfavorable outcomes were examined using univariate and multivariate logistic regression analyses.
Results
A total of 951 patients were included in the study. Multivariate logistic regression analysis showed that the ED length of stay (EDLOS) > 4 h (adjusted odds ratio (AOR) 2.62, 95% confidence interval [CI]: 1.33–5.14; p = 0.005), diastolic blood pressure (DBP) < 80 mmHg (AOR 3.31, 95% CI: 1.71–6.4; p ≤ 0.001), respiratory rate ≥ 24 breaths/min (AOR 2.03, 95% CI: 1.07–3.86; p ≤ 0.031), right lower quadrant (RLQ) tenderness (AOR 3.72, 95% CI: 1.89–7.32; p ≤ 0.001), abdominal distension (AOR 2.91, 95% CI: 1.29–6.57; p = 0.010), hypoactive bowel sounds (AOR 2.89, 95% CI: 1.09–7.67; p = 0.033), presence of specific abdominal signs (AOR 2.07, 95% CI: 1.1–3.88; p = 0.024), white blood cell count ≥ 12,000 cells/mm3 (AOR 2.37, 95% CI: 1.22–4.6; p = 0.011), and absolute neutrophil count (ANC) > 75% (AOR 2.83, 95% CI: 1.39–5.75; p = 0.004) were revealed as significant factors associated with unfavorable outcomes.
Conclusions
The present study revealed that the significant clinical signs associated with the occurrence of unfavorable outcomes were DBP < 80 mmHg, tachypnea (≥ 24 breaths/min), RLQ tenderness, abdominal distension, hypoactive bowel sounds, and presence of specific abdominal signs. Moreover, the associated laboratory results identified in this study were leukocytosis and ANC > 75%. Additionally, patients with abdominal pain visiting the ED who had an EDLOS longer than 4 h were associated with unfavorable outcomes.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12873-022-00761-y.
Keywords: Acute abdominal pain, Emergency department, Unfavorable outcome, Invasive procedure
Background
Acute abdominal pain is a common presenting symptom in the emergency department (ED) accounting for 5–10% of all ED visits [1]. Sometimes the symptoms presented in the ED lead to serious adverse outcomes, particularly in patients with acute abdominal pain. Several modifying factors, such as underlying diseases, immune status, and inability to communicate, can cause a more complicated disease process [2]. The skills of healthcare providers along with effective diagnostic tools are important factors that can lead to an accurate diagnosis and management. Although many advanced diagnostic and therapeutic tools are available, the misdiagnosis rate of acute abdominal pain has changed little over time [2]. A missed diagnosis leads to increased morbidity and mortality. Serious abdominal pathologies that are frequently misdiagnosed include gastroenteritis, gastritis, urinary tract infection, pelvic inflammatory infection, and constipation. Life-threatening conditions sometimes missed in the ED include ruptured abdominal aortic aneurysms, appendicitis, ectopic pregnancy, diverticulitis, a perforated viscus, mesenteric ischemia, and bowel obstruction [1]. Patients who present early and receive immediate corrective measures have better outcomes. However, patients who present late experience unfavorable outcomes, with significantly more complications. Therefore, early detection and treatment of acute abdominal pain are essential [3].
Vital signs are commonly used among triage systems, along with risk scoring tools in the ED [4]. The type and number of abnormal vital signs are strong predictors for in-hospital mortality and admission to the intensive care unit (ICU) [5]. The presentation of a patient with abdominal pain and abnormal vital signs may indicate a serious surgical diagnosis, such as a ruptured abdominal aortic aneurysm, serious intra-abdominal infection, or ruptured hollow viscus organ [6].
Endotracheal intubation and central venous catheter (CVC) placement are common invasive procedures performed in critically ill patients in the ED. Patients who require invasive procedures and are admitted to the ICU from the ED have an in-hospital mortality rate of 21.9% [7]. The reported complications of emergency endotracheal intubation in the ED include hemodynamic collapse (9%), aspiration (4.5%), emergent tracheostomy (1.1%), and pneumothorax (0.6%) [8]. The risks associated with CVC placement range from clinically insignificant to fatal. These risks include bleeding, pneumothorax, nerve injury, and severe arrhythmia [9].
The overall mortality rates of patients in the ED who present with abdominal pain at 24 h and 7 days are 2% and 4%, respectively, whereas the overall in-hospital mortality rate is 8%. The risk factors for mortality are male sex, hypoglycemia, ICU admission, receipt of intravenous fluids, and need for surgery [10].
To the best of our knowledge, factors that affect unfavorable events or outcomes have not been explored. This study aimed to determine the factors associated with unfavorable outcomes in patients with acute abdominal pain visiting the ED.
Methods
Study design and setting
This retrospective cohort study was conducted in the ED of a teaching hospital and a tertiary care medical center with a capacity of 850 beds. The ED has more than 48,000 patient visits per year. The data were collected from July 1, 2015 to June 30, 2016. The inclusion criterion was patients aged older than 18 years with acute abdominal pain visiting the ED. The exclusion criteria were patients scheduled for elective surgery, having undergone previous abdominal surgery within the previous 6 months, with prior diagnosis of cancer, with chronic abdominal pain, with traumatic abdominal pain, who were pregnant, and with incomplete medical records. A total of 951 patients were included in the retrospective study.
Operational definitions
Acute abdominal pain was defined as an abrupt onset of pain or soreness that appeared within 7 days before presenting to the ED and necessitated prompt diagnosis and aggressive treatment, typically a surgical intervention [10, 11]. Unfavorable outcomes were defined as the occurrence of one or more of the following: (i) shock that required an invasive procedure during the ED stay (e.g., CVC insertion and mechanical ventilation), (ii) emergency surgery, (iii) presence of post-operative complications, and (iv) occurrence of in-hospital cardiac arrest (IHCA) in the ED or after admission [3, 12].
Data collection
The data collected from the electronic medical records and ED data registry included baseline characteristics, triage category, physical examination findings, symptom duration, laboratory and imaging results, final diagnosis, treatment in the ED, ED length of stay (EDLOS), ED disposition, morbidity, and mortality. Patients were divided into either an unfavorable outcome group or a favorable outcome group.
Outcome measurements
The primary outcomes were the factors associated with unfavorable outcomes in patients with acute abdominal pain visiting the ED. The secondary outcome was the association between the factors affecting unfavorable outcomes and mortality.
Statistical analyses
The n4Studies tool was used to determine the sample size of the study population to evaluate two independent proportions. The final calculated sample size was 865 patients. After adjusting for a 10% dropout rate, the desired sample size was 952. R software version 4.0.2 was used to perform statistical analyses after all data were imported into EpiData version 3.1 (R Foundation, Vienna, Austria). Continuous variables were analyzed and reported as means and medians whereas categorical variables are reported as percentages. Student’s t-test was used for continuous and ordinal variables and Pearson’s chi-squared test was used for categorical variables. A multivariate logistic regression model was used to evaluate the factors associated with unfavorable outcomes. We determined the factors associated with unfavorable outcomes using backward stepwise logistic regression. Significant factors associated with unfavorable outcomes (p < 0.2) identified during univariate logistic regression analysis were introduced into a subsequent multivariate logistic regression analysis. The optimal clinical cut-off points to predict unfavorable outcome were determined based on the best sensitivity and specificity results. The accuracy of clinical signs and laboratory results of the associated factors to predict unfavorable outcomes was determined using receiver operating characteristic (ROC) curves and area under the ROC curve (AUROC). Model discrimination was rated as good if it produced an AUROC between 0.7 and 0.8 and excellent if it produced an AUROC between 0.8 and 0.9 [13]. Analytical results were described as odds ratio (OR) with 95% confidence interval (CI). Statistical significance was set at p-value < 0.05.
Compliance with ethical requirements
This study was approved by the Ethics Committee of Prince of Songkla University (approval number: REC 58–158-20–1). The Institutional Review Board of Prince of Songkla University is affiliated with the International Conference on Harmonization in Good Clinical Practice. The requirement for informed consent was waived in accordance with our institutional review board's policy because the participants had no greater than minimum risk and the patients received standard medical care. All research information was kept confidential in an encrypted file with a password and limited data access by only the researcher and assistant. This study was conducted in accordance with the principles of Declaration of Helsinki.
Results
Demographic data
A total of 3,784 patients with abdominal discomfort as their primary complaint were registered during the study period. Using a computer-based randomization approach, 951 patients who met the inclusion criterion were selected. Of these, 351 patients (36.9%) were men and 600 patients (63.1%) were women. The baseline characteristics of the unfavorable outcome and favorable outcome groups are shown in Table 1. The median age (interquartile range, IQR) of the unfavorable outcome group was older than the favorable outcome group (51 [29, 65.5] vs. 42 [28, 60]) without statistical significance. Upon comparing the two groups, the statistically significant factors were underlying gastrointestinal disease, triage level, EDLOS, hospital LOS, admission to ward, admission to ICU, discharge from ED, hospital discharge status whether survived or dead, need for consultation, and having consulted specialty.
Table 1.
Clinical factors and baseline characteristics of patients with acute abdominal pain who presented at the ED
| Factors | Unfavorable outcomes (n = 75) | Favorable outcomes (n = 876) | Total (n = 951) |
p-value |
|---|---|---|---|---|
| Age, y, median (IQR) | 51 (29,65.5) | 42 (28,60) | 43 (28,61) | 0.134 |
| Sex | 0.051 | |||
| Male | 36 (48) | 315 (36) | 351 (36.9) | |
| Female | 39 (52) | 561 (64) | 600 (63.1) | |
| Comorbidities | 0.122 | |||
| Present | 44 (58.7) | 426 (48.6) | 470 (49.4) | |
| Absent | 31 (41.3) | 450 (51.4) | 481 (50.6) | |
| Hypertension | 14 (18.7) | 137 (15.6) | 151 (15.9) | 0.600 |
| Gastrointestinal disease | 14 (18.7) | 90 (10.3) | 104 (10.9) | 0.041 |
| Diabetes mellitus | 8 (10.7) | 64 (7.3) | 72 (7.6) | 0.407 |
| Cardiovascular disease | 2 (2.7) | 35 (4) | 37 (3.9) | 0.762 |
| Chronic heart disease | 2 (2.7) | 4 (0.5) | 6 (0.6) | 0.075 |
| Chronic pulmonary disease | 2 (2.7) | 19 (2.2) | 21 (2.2) | 0.678 |
| Cerebrovascular disease | 2 (2.7) | 27 (3.1) | 29 (3) | 1.000 |
| Chronic renal failure | 5 (6.7) | 25 (2.9) | 30 (3.2) | 0.080 |
| Others | 28 (37.3) | 284 (32.4) | 312 (32.8) | 0.458 |
| History of abdominal surgery | 0.957 | |||
| Yes | 9 (12) | 97 (11.1) | 106 (11.1) | |
| No | 66 (88) | 779 (88.9) | 845 (88.9) | |
| Triage levels | < 0.001 | |||
| ESI 1 | 0 | 0 | 0 | |
| ESI 2 | 12 (16) | 32 (3.7) | 44 (4.6) | |
| ESI 3 | 48 (64) | 411 (46.9) | 459 (48.3) | |
| ESI 4 | 14 (18.7) | 402 (45.9) | 416 (43.7) | |
| ESI 5 | 1 (1.3) | 31 (3.5) | 32 (3.4) | |
| Time from onset of symptoms to ED visit (h), median (IQR) | 22 (6.5–24) | 10 (4,39) | 12 (4–30) | 0.145 |
| EDLOS (h), median (IQR) | 5.25 (4.3–6.6) | 2.55 (1.68–3.7) | 2.6 (1.75–4.05) | < 0.001 |
| Hospital LOS (days), median (IQR) | 4.4 (2.5–7.1) | 3.1 (1.2–5.1) | 3.8 (2–6) | 0.004 |
| ED dispositions | ||||
| EDOU | 1 (1.3) | 14 (1.6) | 15 (1.6) | 1.000 |
| Admission to ward | 64 (85.3) | 46 (5.3) | 110 (11.6) | < 0.001 |
| Admission to ICU | 7 (9.3) | 0 (0) | 7 (0.7) | < 0.001 |
| Discharge | 0 (0) | 812 (92.7) | 812 (85.4) | < 0.001 |
| Referred | 2 (2.7) | 5 (0.6) | 7 (0.7) | 0.099 |
| Dead at the ED | 1 (1.3) | 0 (0) | 1 (0.1) | 0.079 |
| Hospital discharge status | < 0.001 | |||
| Survived | 71 (94.7) | 876 (100) | 947 (99.6) | |
| Dead | 4 (5.3) | 0 (0) | 4 (0.4) | |
| Consultation needed | 75 (100) | 77 (8.8) | 152 (16) | < 0.001 |
| Specialty | 0.042 | |||
| Internal medicine | 8 (16.3) | 11 (19.6) | 19 (18.1) | |
| Surgical | 35 (71.4) | 27 (48.2) | 62 (59) | |
| Gynecological | 6 (12.2) | 17 (30.4) | 23 (21.9) | |
| Psychiatry | 0 (0) | 1 (1.8) | 1 (1) | |
Data are presented as n (%), unless otherwise indicated
IQR interquartile range, ESI emergency severity index, ED emergency department, EDLOS emergency department length of stay, LOS length of stay, EDOU emergency department observation unit, ICU intensive care unit
Five diagnoses caused acute abdominal pain in all patients: dyspepsia (23.97%, 228 patients), gastroenteritis (14.93%, 142 patients), ureteric stones (13.88%, 132 patients), urinary tract infection (7.36%, 70 patients), and gynecological conditions (5.99%, 57 patients). The three main diagnoses in the unfavorable outcome group were acute appendicitis (48%, 36 patients), intestinal obstruction (14.66%, 11 patients), and gynecological conditions which included a ruptured ectopic pregnancy (6.66%, 5 patients) and pelvic inflammatory disease (2.66%, 2 patients) (Table 2).
Table 2.
Diagnoses and causes of acute abdominal pain in the study population
| Unfavorable outcomes (n = 75) | Favorable outcomes (n = 876) |
Total (n = 951) |
p-value | |
|---|---|---|---|---|
| Emergency department diagnosis | < 0.001 | |||
| Cause identified | 75 (100) | 753 (86) | 828 (87.1) | |
| Nonspecific abdominal pain | 0 (0) | 123 (14) | 123 (12.9) | |
| Gastrointestinal conditions | 67 (89.3) | 517 (59) | 584 (61.4) | < 0.001 |
| Appendicitis | 36 (53.7) | 11 (2.1) | 47 (8) | < 0.001 |
| Gallstones | 2 (3) | 22 (4.3) | 24 (4.1) | 1.000 |
| Diverticulitis | 3 (4.5) | 7 (1.4) | 10 (1.7) | 0.096 |
| Constipation | 1 (1.5) | 31 (6) | 32 (5.5) | 0.159 |
| Hollow viscus organ perforation | 4 (6) | 0 (0) | 4 (0.7) | < 0.001 |
| Cholecystitis | 2 (3) | 7 (1.4) | 9 (1.5) | 0.276 |
| Pancreatitis | 4 (6) | 5 (1) | 9 (1.5) | 0.013 |
| Intestinal obstruction | 11 (16.4) | 13 (2.5) | 24 (4.1) | < 0.001 |
| Gastroenteritis | 0 (0) | 142 (27.5) | 142 (24.3) | < 0.001 |
| Dyspepsia | 1 (1.5) | 227 (43.9) | 228 (39) | < 0.001 |
| Peptic ulcer | 0 (0) | 2 (0.4) | 2 (0.3) | 1.000 |
| Aortic aneurysm | 1 (1.5) | 0 (0) | 1 (0.2) | 0.115 |
| Colonic obstruction | 1 (1.5) | 1 (0.2) | 2 (0.3) | 0.216 |
| Cholelithiasis/biliary tract disease | 3 (4.5) | 11 (2.1) | 14 (2.4) | 0.21 |
| Others | 9 (13.4) | 72 (13.9) | 81 (13.9) | 1.000 |
| Genitourinary conditions | 3 (4) | 189 (21.6) | 192 (20.2) | < 0.001 |
| Ureteric stone | 1 (33.3) | 131 (69.3) | 132 (68.8) | 0.231 |
| Urinary tract infection | 1 (33.3) | 69 (36.5) | 70 (36.5) | 1.000 |
| Other genitourinary conditions | 1 (33.3) | 5 (2.6) | 6 (3.1) | 0.091 |
| Gynecological conditions | 7 (9.3) | 50 (5.7) | 57 (6) | 0.203 |
| Ectopic pregnancy with complication | 5 (71.4) | 0 (0) | 5 (8.8) | < 0.001 |
| Ectopic pregnancy without complication | 0 (0) | 1 (2) | 1 (1.8) | 1.000 |
| Ovarian disease with complication | 0 (0) | 5 (10) | 5 (8.8) | 1.000 |
| Ovarian disease without complication | 0 (0) | 1 (2) | 1 (1.8) | 1.000 |
| Pelvic inflammatory disease | 2 (28.6) | 7 (14) | 9 (15.8) | 0.304 |
| Tubo-ovarian abscess | 0 (0) | 1 (2) | 1 (1.8) | 1.000 |
| Other gynecological conditions | 0 (0) | 36 (72) | 36 (63.2) | < 0.001 |
| Extra-abdominal conditions | 0 (0) | 15 (1.7) | 15 (1.6) | 0.623 |
Data are presented as n (%)
Factors affecting the occurrence of unfavorable outcomes
An EDLOS longer than 4 h was highly associated with predicting the occurrence of unfavorable outcome with an AUROC of 0.783, and EDLOS had a high negative predictive value of 98%. The study period also had 77% sensitivity and 79% specificity for predicting unfavorable outcomes (Table 3). The univariate logistic regression analysis showed that the presence of comorbidities of chronic heart disease (OR 5.97, 95% CI: 1.08–33.16), emergency severity index triage level 2 (OR 11.62, 95% CI: 1.43–94.83), and EDLOS longer than 4 h (OR 13.1, 95% CI: 7.45–23.04) increased the likelihood of unfavorable outcomes. Furthermore, the following physical examination findings also increased the likelihood of unfavorable outcome: presence of hypotension (systolic blood pressure [< 100 mmHg]) (OR 3.28, 95% CI: 0.89–12.01), diastolic blood pressure (DBP) < 80 mmHg (OR 3.01, 95% CI: 1.78–5.11, tachycardia (heart rate > 90 bpm) (OR 2.39, 95% CI:1.49–3.85), tachypnea (respiratory rate [RR] ≥ 30 breaths/min) (OR 5.02, 95% CI: 2.4–10.51), and fever (body temperature ≥ 38 °C) (OR 6.58, 95% CI: 3.31–13.11). Moreover, the abdominal signs identified on univariate logistic regression analysis with high ORs were generalized abdominal rigidity/guarding (OR 39.68, 95% CI: 10.49–150.1), localized rigidity/guarding (OR 22.31, 95% CI: 7.86–63.3), right lower quadrant (RLQ) tenderness (OR 6.9, 95% CI: 3.83–10.33), and hypoactive bowel sounds (OR 6.26, 95% CI: 3.16–12.38). An absolute neutrophil count (ANC) > 75% (OR 4.4, 95% CI: 2.44–7.93), white blood cell (WBC) count ≥ 12,000 cells/mm3 (OR 3.39, 95% CI: 2–5.74), and lymphopenia < 15% (OR 3.4, 95% CI:1.95–5.95) were also associated with unfavorable outcomes (Table 4). However, EDLOS > 4 h, DBP < 80 mmHg, RR > 24 breaths/min, RLQ tenderness, abdominal distension, hypoactive bowel sounds, presence of specific abdominal signs (i.e., Murphy’s sign, Rovsing’s sign, psoas sign), WBC count ≥ 12,000 cells/mm3, and ANC > 75% were revealed to be significant factors in the multivariate logistic regression analysis, with statistical significance (Table 5).
Table 3.
Accuracy of vital signs, abdominal signs, and laboratory results in predicting unfavorable outcomes in patients with acute abdominal pain
| Variables | AUROC | Sensitivity | Specificity | LR + (95% CI) |
LR − (95% CI) |
PPV | NPV |
|---|---|---|---|---|---|---|---|
| Age ≥ 65 years | 0.5530594 | 0.29 | 0.81 | 1.57 | 0.87 | 0.12 | 0.93 |
| Vital signs | |||||||
| SBP < 125 mmHg | 0.5605708 | 0.45 | 0.67 | 1.36 | 0.82 | 0.10 | 0.93 |
| SBP < 100 mmHg | 0.5137215 | 0.04 | 0.99 | 3.19 | 0.97 | 0.21 | 0.92 |
| DBP < 80 mmHg | 0.6280822 | 0.73 | 0.52 | 1.54 | 0.51 | 0.12 | 0.96 |
| RR ≥ 24 breaths/min | 0.5650228 | 0.59 | 0.54 | 1.28 | 0.76 | 0.10 | 0.94 |
| Abdominal tenderness | |||||||
| Generalized | 0.6722063 | 0.47 | 0.88 | 3.82 | 0.61 | 0.25 | 0.95 |
| Epigastrium | 0.5709132 | 0.24 | 0.90 | 2.44 | 0.84 | 0.17 | 0.93 |
| RLQ | 0.5756393 | 0.19 | 0.96 | 5.27 | 0.84 | 0.31 | 0.93 |
| RUQ | 0.610137 | 0.63 | 0.59 | 1.54 | 0.63 | 0.12 | 0.95 |
| Laboratory results | |||||||
| WBC count ≥ 12,000 | 0.6469595 | 0.61 | 0.69 | 1.94 | 0.57 | 0.33 | 0.88 |
| ANC > 75% | 0.6689189 | 0.77 | 0.57 | 1.78 | 0.40 | 0.31 | 0.91 |
| EDLOS > 4 h | 0.7833562 | 0.77 | 0.79 | 3.74 | 0.29 | 0.24 | 0.98 |
AUROC area under receiver operating characteristic curve, LR + positive likelihood ratio, LR − negative likelihood ratio, PPV positive predictive value, NPV negative predictive value, CI confidence interval, SBP systolic blood pressure, DBP diastolic blood pressure, RR respiratory rate, RLQ right lower quadrant, RUQ right upper quadrant, WBC white blood cell, ANC absolute neutrophil count, EDLOS emergency department length of stay
Table 4.
Univariate logistic regression analysis of factors that affected unfavorable outcomes
| Variables | Odds ratio | 95% CI | p-value |
|---|---|---|---|
| Sex: male vs. female | 1.64 | 1.02–2.64 | 0.04 |
| Age ≥ 65 y | 1.8 | 1.07–3.05 | 0.028 |
| Presence of comorbidities | 1.5 | 0.93–2.42 | 0.097 |
| Chronic heart disease | 5.97 | 1.08–33.16 | 0.041 |
| Chronic renal failure | 2.43 | 0.9–6.55 | 0.079 |
| Gastrointestinal disease | 2.0 | 1.08–3.73 | 0.028 |
| Triage level | |||
| ESI 2 | 11.62 | 1.43–94.83 | 0.022 |
| ESI 3 | 3.62 | 0.48–27.12 | 0.21 |
| ESI 4 | 1.08 | 0.14–8.48 | 0.942 |
| Onset of symptoms to ED visit > 12 h | 1.73 | 1.07–2.8 | 0.026 |
| EDLOS > 4 h | 13.1 | 7.45–23.04 | < 0.001 |
| Hospital length of stay > 7 days | 2.17 | 0.87–5.41 | 0.098 |
| Vital signs | |||
| SBP < 125 mmHg | 1.67 | 1.04–2.68 | 0.035 |
| SBP < 100 mmHg | 3.28 | 0.89–12.01 | 0.073 |
| DBP < 80 mmHg | 3.01 | 1.78–5.11 | < 0.001 |
| Heart rate ≥ 90 bpm | 2.39 | 1.49–3.85 | < 0.001 |
| RR ≥ 24 breaths/min | 1.69 | 1.05–2.73 | 0.032 |
| RR ≥ 30 breaths/min | 5.02 | 2.4–10.51 | < 0.001 |
| BT ≥ 37.5 °C | 5.02 | 3.04–8.29 | < 0.001 |
| BT ≥ 38 °C | 6.58 | 3.31–13.11 | < 0.001 |
| Abdominal tenderness | |||
| Generalized | 2.3 | 1.18–4.48 | 0.014 |
| Epigastrium | 0.36 | 0.17–0.77 | 0.008 |
| RLQ | 6.9 | 3.83–10.33 | < 0.001 |
| RUQ | 2.04 | 0.96–4.3 | 0.063 |
| Abdominal distension | 2.9 | 1.63–5.15 | < 0.001 |
| Generalized rigidity/guarding | 39.68 | 10.49,150.1 | < 0.001 |
| Localized rigidity/guarding | 22.31 | 7.86–63.3 | < 0.001 |
| Hypoactive bowel sounds | 6.26 | 3.16–12.38 | < 0.001 |
| Presence of specific abdominal signs | 2.45 | 1.51–3.99 | < 0.001 |
| Digital rectal examination | 3.3 | 1.74–6.25 | < 0.001 |
| Laboratory results | |||
| White blood cell count ≥ 12,000 | 3.39 | 2–5.74 | < 0.001 |
| White blood cell count ≥ 14,000 | 3.19 | 1.86–5.5 | < 0.001 |
| ANC > 75% | 4.4 | 2.44–7.93 | < 0.001 |
| Lymphocytes < 15% | 3.4 | 1.95–5.95 | < 0.001 |
| Positive urinalysis | 0.3 | 0.15–0.59 | < 0.001 |
CI confidence interval, ESI emergency severity index, ED emergency department, EDLOS emergency department length of stay, SBP systolic blood pressure, DBP diastolic blood pressure, RR respiratory rate, BT body temperature, RLQ right lower quadrant, RUP right upper quadrant, ANC absolute neutrophil count
Table 5.
Multivariate logistic regression analysis of factors that affected unfavorable outcomes
| Variables | Crude OR (95% CI) | AOR (95% CI) | p-value |
|---|---|---|---|
| EDLOS > 4 h | 4.05 (2.25–7.3) | 2.62 (1.33–5.14) | 0.005 |
| Vital signs | |||
| DBP < 80 mmHg | 2.7 (1.54–4.73) | 3.31 (1.71–6.4) | < 0.001 |
| RR ≥ 24 breaths/min | 1.59 (0.95–2.66) | 2.03(1.07–3.86) | 0.031 |
| Abdominal signs | |||
| RLQ tenderness | 3.34 (1.95–5.73) | 3.72 (1.89–7.32) | < 0.001 |
| Abdominal distension | 2.12 (1.13–3.97) | 2.91 (1.29–6.57) | 0.01 |
| Hypoactive bowel sounds | 3.73 (1.71–8.16) | 2.89 (1.09–7.67) | 0.033 |
| Presence of specific abdominal signs | 2.1 (1.24–3.54) | 2.07 (1.1–3.88) | 0.024 |
| Laboratory results | |||
| WBC count ≥ 12,000 cells/mm3 | 3.39 (2–5.74) | 2.37 (1.22–4.6) | 0.011 |
| ANC > 75% | 4.4 (2.44–7.93) | 2.83 (1.39–5.75) | 0.004 |
OR odds ratio, AOR adjusted odds ratio, EDLOS emergency department length of stay, DBP diastolic blood pressure, RR respiratory rate, RLQ right lower quadrant, WBC white blood cell, ANC absolute neutrophil count
Unfavorable outcomes and the mortality group
Significant variables associated with in-hospital mortality in the unfavorable outcome group were the presence of shock, mechanical ventilation used, need for emergency surgery, and occurrence of IHCA (Table 6). The emergency surgical procedures performed included appendectomy (58.5%, 38 patients), exploratory laparotomy (29.2%, 19 patients), laparoscopy (7.7%, 5 patients), and cholecystectomy (4.6%, 3 patients). Three patients died after admission and one patient died in the ED. The diagnoses of the deceased patients in the unfavorable outcome group are shown in Table 7.
Table 6.
Characteristics in the unfavorable outcome and hospital mortality group
|
Survived (n = 71) |
Dead (n = 4) |
Total (n = 75) |
p-value | |
|---|---|---|---|---|
| Shock | 8 (11.3) | 4 (100) | 12 (16) | < 0.001 |
| Type of shock | ||||
| • Septic | 4 (50) | 3 (75) | 7 (58.3) | 0.576 |
| • Hypovolemic | 5 (62.5) | 1 (25) | 6 (50) | 0.545 |
| • Cardiogenic | 1 (12.5) | 0 (0) | 1 (8.3) | 1.000 |
| Place of shock | 0.632 | |||
| ED | 6 (75) | 2 (50) | 8 (66.7) | |
| Ward | 1 (12.5) | 1 (25) | 2 (16.7) | |
| ICU | 0 (0) | 1 (25) | 1 (8.3) | |
| EDOU | 1 (12.5) | 0 (0) | 1 (8.3) | |
| Invasive procedure performed | ||||
| • CVC insertion | 7 (58.3) | 4 (100) | 11 (68.8) | 0.245 |
| • Mechanical ventilation | 2 (16.7) | 4 (100) | 6 (37.5) | 0.008 |
| Emergency surgery | 64 (90.1) | 1 (25) | 65 (86.7) | 0.007 |
| • Exploratory laparotomy | 18 (25.3) | 1 (25) | 19 (25.3) | |
| • Appendectomy | 38 (58.3) | 0 | 38 (58.3) | |
| • Laparoscopy | 5 (7.7) | 0 | 5 (7.7) | |
| • Cholecystectomy | 3 (4.6) | 0 | 3 (4.6) | |
| Postoperative complication | 5 (7) | 1 (25) | 6 (8) | 0.289 |
| In-hospital cardiac arrest | 0 (0) | 2 (50) | 2 (2.7) | 0.002 |
Data are presented as n (%)
ED emergency department, ICU intensive care unit, EDOU emergency department observation unit, CVC, central venous catheter
Table 7.
Diagnoses of the deceased patients in the unfavorable outcome group
| No | Profile | Diagnosis | Adverse events/outcome | Surgical procedure | EDLOS | Hospital mortality |
|---|---|---|---|---|---|---|
| 1 |
52 YOM Liver cirrhosis, AIHA on prednisolone |
Acute cholecystitis, secondary peritonitis | Septic shock, CVC insertion, mechanical ventilation, cardiac arrest | No | 8 h 33 min | Dead at the ED |
| 2 |
83 YOM Ischemic heart disease |
Acute cholangitis (gallstone), splenic infarction | Septic shock, CVC insertion, mechanical ventilation | ERCP | 5 h 15 min | 5 days |
| 3 |
83 YOF CKD, COPD |
Colitis, diverticular disease | Septic shock, CVC insertion, mechanical ventilation, cardiac arrest | No | 6 h 10 min | 5 days |
| 4 |
79 YOM Ischemic stroke |
Ruptured infrarenal AAA | Hypovolemic shock, CVC insertion, mechanical ventilation, post-op complication | Open abdominal aortic repair | 1 h 15 min | 26 days |
EDLOS emergency department length of stay, YOM year-old male, AIHA autoimmune hemolytic anemia, YOF year-old female, CKD chronic kidney disease, COPD chronic obstructive pulmonary disease, AAA abdominal aortic aneurysm, CVC central venous catheter, ERCP endoscopic retrograde cholangiopancreatography
Discussion
There are various definitions of unfavorable outcome related to acute abdominal pain. Most studies focused on the risk associated with surgical intervention or post-operative complications that included surgical site infection, severe sepsis, hospital readmission, admission to the ICU, prolonged hospital stay, and increased hospital mortality [14, 15].
The statistically significant factors (i.e., clinical signs) that were associated with the occurrence of unfavorable outcomes in the multivariate logistic regression analysis were DBP < 80 mmHg, tachypnea (RR ≥ 24 breaths/min), RLQ tenderness, abdominal distension, hypoactive bowel sounds, presence of specific abdominal signs (i.e., Murphy’s sign, Rovsing’s sign, psoas sign), leukocytosis (WBC count ≥ 12,000 cells/mm3), ANC > 75%, and EDLOS longer than 4 h.
In our analysis, the vital sign parameters measured at the triage area that were identified as significant factors for the occurrence of unfavorable outcomes in both the univariate and multivariate logistic regression analyses were DBP < 80 mmHg with an adjusted odds ratio (AOR) of 3.31 and RR ≥ 24 breaths/min with an AOR of 2.03. This is in accordance with the result of Barfod’s study. They found that abnormal RR, oxygen saturation (SpO2), and Glasgow Coma Scale score were significant risk factors associated with adverse outcome and in-hospital mortality [5]. The study population in this cohort, with abdominal pain as the chief complaint accounted for 20.1% of the study patients and had an in-hospital mortality rate of 3.1%. Blood pressure < 80 mmHg and RR of 26–30 breaths/min had AOR values of 3.87 and 1.89, respectively, but in-hospital mortality was not statistically significant [5]. Increased in-hospital mortality was associated with abnormal vital signs or the presence of hypotensive shock during the ED visit. One large observational multicenter study conducted in adult patients visiting the ED reported that 14% of the study population presented with abdominal pain. The study concluded that the in-hospital patient mortality rate increased gradually with worsening SBP and DBP values. SBP values of 81–100 mmHg and 0–80 mmHg had AORs of 2.62 and 4.07 for mortality, respectively, whereas DBP values of 61–80 mmHg and 0–60 mmHg had AORs of 1.23 and 2.12 for mortality, respectively. However, the study did not report clear cut-off points for SBP, DBP, SpO2, or heart rate and did not provide AORs for mortality. The AOR for RR gradually increased between 10 and 19 breaths/min with a substantial increase in mortality at 22 breaths/min [16]. Tringali et al.’s study reported that DBP values below 70 mmHg were associated with increased all-cause mortality in patients aged 45 years or older who encountered outpatient care [17]. Most studies used DBP ≤ 60 mmHg to indicate an impending serious adverse event; however, at this low level, it may be significantly late to detect the abnormality, which may lead to delayed treatment [4, 5, 17]. A previous study explored the predictors of poor outcomes in geriatric patients with acute abdominal pain. According to the study, hypotension, abnormal abdominal radiography findings, leukocytosis, abnormal bowel sounds, and advanced age were the independent predictors of unfavorable outcomes [18].
Ancillary studies should be used only as adjunct information for the clinician's diagnosis based on the clinical symptoms and signs. A diagnostic test resulted in changing the diagnosis in 37% of patients and changing the disposition in 41% of patients in a small prospective trial that evaluated diagnostic testing for nontraumatic abdominal pain in the ED [19]. A complete blood count helps to determine the diagnosis but it is nonspecific and rarely leads to therapy modification. Up to 80% of patients with acute appendicitis may have a high WBC count, but 70% of patients with other causes of RLQ abdominal pain also have an elevated WBC count [20]. However, evidence from a previous study showed that leukocytosis and relative lymphopenia were the only variables meaningfully associated with the presence of a major pathology on computed tomography, and the coexistence of these two anomalies may be sufficient to justify abdominal computed tomography [21]. In accordance with our findings, leukocytosis (WBC count ≥ 12,000 cells/mm3) and an ANC > 75% were associated with unfavorable outcomes with AOR values of 2.37 and 2.83, respectively. One of the unfavorable outcome indicators in the present study was the need for emergency surgery, which may indicate to a significant intra-abdominal pathology.
A combination of abdominal signs and presenting symptoms of a patient provides fundamental clinical information clues to establish a diagnosis. The present study explored several physical signs associated with unfavorable outcomes, including RLQ tenderness, abdominal distension, hypoactive bowel sounds, and presence of specific abdominal signs (Murphy’s sign, Rovsing’s sign, psoas sign). Murphy’s sign for acute cholecystitis and Rovsing’s sign and the psoas sign for acute appendicitis are specific abdominal signs that increase the likelihood of an intra-abdominal pathology, which can lead to a precise diagnosis with a wide range of sensitivity and specificity values [22]. From the results of the current study, 48% (36/75) of the patients in the unfavorable outcome group had acute appendicitis. Thus, RLQ tenderness and certain abdominal signs (i.e., Rovsing’s and psoas signs) were associated with unfavorable outcome. Since the abdomen of patients with severe peritonitis is often distended with hypoactive to absent bowel sounds [23], these clinical presentations were significant factors in predicting unfavorable outcomes in our study. One cross-sectional hospital-based longitudinal case series analysis of patients admitted and operated on for acute abdominal pain found that the most frequent signs observed were abdominal tenderness (78.3%), abdominal distension (67.8%), and abnormal bowel sounds (49.7%). They also identified less common abdominal signs, which included guarding (39.2%), abdominal mass (24.5%), positive rectal exam (36.4%), and positive vaginal exam (10.5%), which were found to be significantly associated with adverse outcomes [3]. The results of that study were similar to our study in that generalized/localized abdominal rigidity or abdominal guarding in the univariate logistic regression analysis indicated significantly high odds ratios of 39.68 (95% CI: 10.49, 150.1) and 22.31 (95% CI: 7.86, 63.3), respectively. However, these parameters were not identified in the multivariate logistic regression analysis. The study population in the referenced study was different from that in our study because they included patients of all age groups, but we included only adult patients.
In the present study, four patients in the unfavorable outcome group died within 28 days after admission (Table 7). Three of them had an EDLOS longer than 4 h due to the severity of septic shock and the need for critical care interventions. The patient who died at the ED at 8 h 33 min presented with liver cirrhosis and autoimmune hemolytic anemia and was taking immunosuppressive medication that altered his immune function and defense mechanism against infection [24]. The ability to effectively manage and treat critically ill patients in the ED decreases with overcrowding. EDLOS is a crucial metric for tracking the effectiveness of ED management and has a direct effect on ED overcrowding. Hospital admission rates, 10-day mortality, and dissatisfaction have been associated with longer EDLOS durations [25, 26]. A previous study conducted in our institute reported on the significant factors associated with EDLOS ≥ 4 h in patients who presented with abdominal pain in the ED. After performing multivariate logistic regression analysis, age, rounds of blood testing, interdepartmental consultation, and the need for ultrasonography were associated with an EDLOS ≥ 4 h. We also demonstrated that mortality occurred in a small number of patients who experienced an extended EDLOS. The patients were diagnosed psoas abscess, ruptured hepatoma, acute pancreatitis, and intestinal obstruction with EDLOS times of 12 h 14 min, 4 h 10 min, 5 h 40 min, and 5 h, respectively [26]. However, our previous study did not explore the possible association between EDLOS and unfavorable outcomes.
Limitations
This study has several limitations. First, it was retrospective in nature and conducted in a single ED. Second, the patients were randomly selected using a computerized procedure; therefore, some characteristics may not have been presented, especially in the unfavorable outcome group. Third, we did not perform a subgroup analysis of patients who underwent emergency surgery, which may have revealed more specific information.
Conclusions
The present study revealed that significant clinical signs associated with unfavorable outcome were DBP < 80 mmHg, tachypnea (RR ≥ 24 breaths/min), RLQ tenderness, abdominal distension, hypoactive bowel sounds, and presence of specific abdominal signs. Moreover, the associated laboratory results identified in this study were leukocytosis (WBC count ≥ 12,000 cells/mm3) and ANC > 75%. Finally, patients with abdominal pain visiting the ED who had an EDLOS > 4 h were associated with unfavorable outcome.
Supplementary Information
Additional file 1: Supplementary 1. Comparison of abdominal imaging, investigationresults, and outcomes.
Acknowledgements
The author thanks Kingkarn Waiyanak for the search and retrieval of articles, Glenn K. Shingledecker for his help in editing the manuscript, Editage.com for final English language editing, the Epidemiology Unit for their assistance, and the Faculty of Medicine for funding this study.
Abbreviations
- AAA
Abdominal aortic aneurysm
- AIHA
Autoimmune hemolytic anemia
- ANC
Absolute neutrophil count
- AOR
Adjusted odds ratio
- AUROC
Area under receiver operating curve
- BT
Body temperature
- CI
Confidence interval
- CVC
Central venous catheter
- DBP
Diastolic blood pressure
- ED
Emergency department
- EDLOS
Emergency department length of stay
- EDOU
Emergency department observation unit
- ESI
Emergency severity index
- ICU
Intensive care unit
- IHCA
In-hospital cardiac arrest
- LOS
Length of stay
- LR −
Negative likelihood ratio
- LR +
Positive likelihood ratio
- NPV
Negative predictive value
- OR
Odds ratio
- PPV
Positive predictive value
- RLQ
Right lower quadrant
- ROC
Receiver operating curve
- RR
Respiratory rate
- RUQ
Right upper quadrant
- SBP
Systolic blood pressure
- SpO2
Oxygen saturation
- WBC
White blood cell
- YOF
Year-old female
- YOM
Year-old male
Authors’ contributions
Dadeh AA contributed in the study design, data collection, data analysis, data interpretation and writing of the manuscript. The author read and approved the final manuscript.
Funding
The Faculty of Medicine of Prince of Songkla University funded this study.
Availability of data and materials
Retrospective data used to support the findings of this study are available from the corresponding author upon request.
Declarations
Ethics approval and consent to participate
The author confirmed that all methods were performed in accordance with relevant guidelines and regulations. This study was approved by the Ethics Committee of the Faculty of Medicine of Prince of Songkla University (Ref. No.: REC 58–158-20–1.). The requirement for informed consent was waived in accordance with our institutional review board's policy because the participants had no greater than minimum risk and the patients received standard medical care and owing to the retrospective nature of the study. The waived procedure was approved by the Ethics Committee of the Faculty of Medicine of Prince of Songkla University (Ref. No.: REC 58–158-20–1.).
Consent for publication
Not applicable.
Competing interests
The author declares no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Additional file 1: Supplementary 1. Comparison of abdominal imaging, investigationresults, and outcomes.
Data Availability Statement
Retrospective data used to support the findings of this study are available from the corresponding author upon request.