Archives of Academic Emergency Medicine. 2023; 11(1): e32 OR I G I N A L RE S E A RC H Ottawa Risk Scale in Predicting the Outcome of Chorionic Obstructive Pulmonary Disease Exacerbation in Emer- gency Department; a Diagnostic Accuracy Study Mostafa Alavi-Moghaddam1, Hossein Partovinezhad2, Shayan Dasdar3, Maryam Farjad1∗ 1. Emergency Department, Imam Hossein Hospital, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2. Emergency Department, Zanjan University of Medical Sciences, Zanjan, Iran. 3. Men’s Health and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Received: January 2023; Accepted: February 2023; Published online: 9 April 2023 Abstract: Introduction: The disposition decision is a great challenge for clinicians in managing patients with chronic obstructive pulmonary disease (COPD) exacerbation. This study aimed to evaluate the accuracy of Ottawa COPD Risk Scale (OCRS) in predicting the short-term adverse events in the mentioned patients. Methods: This prospective diagnostic accuracy study was conducted on COPD exacerbation cases who were referred to the emergency department (ED). Patients were followed up for 30 consecutive days for adverse events including the need for intubation, non-invasive ventilation, my- ocardial infarction, readmission, and death from any cause, and finally the accuracy of OCRS in predicting the outcome was evaluated. Results: 362 patients with the mean age of 65.55 ± 10.65 (6- 95) years were evaluated (58.0% male). Among the patients, 164 (45.3%) cases were discharged from ED, and 198 (54.7%) were admitted to the hospital. 136 (37.6%) cases experienced at least one of the studied short-term adverse events. The mean OCSD score of this series was 1.96 ± 2.39 (0 – 10). The area under the curve of OCRS in predicting the outcome of COPD patients was 0.814 (95%CI: 0.766 – 0.862). The best cut-off point of the scale in predicting the outcome was 1.5. The sensitivity and specificity of the scale were 75.75% (95%CI: 69.6% – 81.42%) and 89.63% (95%CI: 83.67% – 93.66%), respectively. By employing this threshold, 48 (13.25%) cases would have unnecessary hospitalization, and 17 (0.04%) would be discharged incorrectly. Conclusion: The OCRS has acceptable level of prediction accuracy in predicting the short-term adverse event of COPD patients. The use of this scoring in the routine practice of ED clinicians can lead to a reduction in unnecessary admis- sions and unsafe discharge for these patients. Keywords: Pulmonary Disease, Chronic Obstructive; Risk Assessment; Patient Outcome Assessment; Sensitivity and Specificity; Clinical Decision Rules Cite this article as: Alavi-Moghaddam M, Partovinezhad H, Dasdar S, Farjad M. Ottawa Risk Scale in Predicting the Outcome of Chorionic Obstructive Pulmonary Disease Exacerbation in Emergency Department; a Diagnostic Accuracy Study. Arch Acad Emerg Med. 2023; 11(1): e32. https://doi.org/10.22037/aaem.v11i1.2023. 1. Introduction Chronic obstructive pulmonary disease (COPD) is a serious and frequent respiratory condition ranking as the third cause of disability-adjusted life-years among old aged people ac- cording to the latest Global Burden of Disease (1). Each year, more than 3 million people die from COPD around the world (2). This respiratory disorder, mostly caused by smoking, is characterized by progressive and poorly reversible airway ob- ∗Corresponding Author: Maryam Farjad; Emergency Department, Imam Hossein Hospital, Shahid Madani Avenue, Imam Hossein Square, Tehran, Iran. Tel: 00989123178240, Email: farjad.mary@gmail.com, ORCID: https://orcid.org/0000-0002-1000-6495. struction due to chronic inflammation (3). Exacerbation of COPD is defined as an acute deterioration in the usual stable course of the disease. This condition could lead to many emergency department (ED) visits (4). Patients with COPD exacerbation could sufficiently benefit from treatments in the ED to be discharged after a few hours with no risk. However, a small number of the patients might experience critical short-term adverse events, necessitating hospital admission and aggressive management to ensure a safe outcome (5). It is not reasonable to admit all patients with COPD exacerba- tion, as many hospitals have a shortage of beds and staff. On the other hand, unnecessary hospital admission could bear undesirable health and financial consequences. Therefore, This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index M. Alavi-Moghaddam et al. 2 the disposition decision is a great challenge for clinicians in managing patients with COPD exacerbation (6). A valid set of criteria in deciding whether to continue treatment in the ED, admit, or discharge the patients would be cost-effective and safe. Therefore, the scores and tools that have been de- veloped to predict the outcomes of COPD exacerbation are very helpful. The Ottawa COPD Risk Scale (OCRS) is a tool designed to pre- dict outcomes of COPD exacerbation. The primary purpose of this scale is to assist physicians in deciding whether to ad- mit COPD patients or discharge them with no need for com- plex and expensive diagnostic tests (7). Utilizing the OCRS in the disposition decision of patients with COPD exacerba- tion in ED can remarkably reduce unnecessary hospitaliza- tions and unsafe discharges (8). To date, few studies have assessed the validity of OCRS prospectively. Therefore, we aimed to evaluate the accuracy of the OCRS in predicting short-term adverse events of the patients with COPD exacerbation, referred to the ED. 2. Methods 2.1. Study design and setting This prospective diagnostic accuracy study was conducted at Imam Hossein and Shohadaye Tajrish Hospitals in Tehran, Iran, affiliated with Shahid Beheshti University of Medical Sciences, from January 2021 to December 2022. All patients were informed about the study’s purpose and procedures, and written informed consents were obtained. The study protocol was in accordance with the Declaration of Helsinki. The institutional review board of Shahid Beheshti University of Medical Sciences reviewed and approved this study (Ethics code: IR.SBMU.MSP.REC.1398.271). 2.2. Study population All patients with COPD exacerbation who attended the ED were studied. The inclusion criteria were 1) admission with COPD exacerbation, defined as increase in at least two of the following symptoms two symptoms of breathlessness, spu- tum volume and sputum purulence; 2) previous COPD diag- nosis or a history of at least one year of chronic dyspnea or cough with sputum; 3) a history of at least 15 pack-years of smoking with moderate to severe airflow obstruction; 4) age 50 years or older. The extremely ill patients who, after 2 to 12 hours of man- agement in ED, had a saturation of oxygen <85%, heart rate >130 beats/min, systolic blood pressure < 85mmHg, confu- sion, long-term hemodialysis, chest pain indicating heart at- tack requiring treatment, or ST–T interval changes indicating ischemia were excluded. The inclusion and exclusion criteria were selected upon the original study of the OCRS by Stiell et al. (8). Table 1: Baseline characteristics of the studied cases Variable Value Gender Male 210 (58.0) Female 152 (42.0) Age (year) Mean ± SD 65.55 ± 10.65 Triage level (ESI) 1 44 (12.2) 2 51 (14.1) 3 267 (73.8) Medical history Hypertension 210 (59.2) Diabetes mellitus 65 (18.3) Heart failure 41 (11.5) Chronic renal failure 6 (1.7) Stroke 23 (6.2) Cancer 11 (3.1) Surgical history Coronary artery bypass graft 23 (6.4) Percutaneous coronary intervention 7 (1.9) Peripheral vascular intervention 64 (17.7) History of intubation Yes 11 (3.0) No 351 (97.0) Vital signs on arrival Hear rate (/minute) 94.85 ± 18.89 Respiratory rate (/minute) 9.61 ± 4.13 Temperature (Celsius) 36.90 ± 3.08 O2 Saturation (%) 86.75 ± 6.73 ECG on arrival Atrial filtration 34 (9.4) Right axis deviation 110 (30.4) Atrioventricular block 54 (14.9) Right bundle branch block 81 (22.4) Sinus tachycardia 104 (28.7) Chest x-ray findings Pneumonia 109 (30.1) Plural effusion 98 (27.1) Cardiomegaly 140 (38.7) O2 therapy in emergency department Venturi mask 187 (51.7) Non-rebreathing mask 141 (39.0) Non-invasive ventilation 17 (4.7) Data are presented as mean ± standard deviation (SD) or frequency (%). ESI: emergency severity index; ECG: electrocardiography. 2.3. Data gathering A general practitioner was responsible for data gathering un- der the direct supervision of an emergency physician special- ist. The following data were collected from the enrolled pa- tients: gender, age, triage level, medical and surgical history, previous intubation, arrival vital signs (blood pressure, heart rate, respiratory rate, temperature, oxygen saturation), elec- trocardiography (ECG) on arrival, findings of the chest X-ray, This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index 3 Archives of Academic Emergency Medicine. 2023; 11(1): e32 Table 2: Screening performance characteristics of the Ottawa Risk Scale in predicting the outcome of patients with chronic obstructive pulmonary disease (COPD) Characteristics Value (95%CI) Sensitivity 75.75% (69.6% – 81.42%) Specificity 89.63% (83.67% – 93.66%) Positive predictive value 89.82% (83.95% – 93.78%) Negative predictive value 75.38% (68.61% – 81.13%) Positive likelihood ratio 8.82 (5.60 – 13.88) Negative likelihood ratio 0.32 (0.25 – 0.41) Total accuracy 86.5% (82.7% – 90.3%) CI: confidence interval. and O2 therapy in the ED. The OCRS score was calculated for all the patients in a 3-stage review system. 1) Initial assess- ment step: history of coronary artery bypass graft (CABG), history of intervention for peripheral vascular disease, his- tory of intubation for respiratory distress, and arrival heart rate >110 beats/min. 2) Investigations step: acute ischemic changes in arrival ECG, evidence of pulmonary congestion on chest X-ray, hemoglobin <100 g/L, urea >12 mmol/L, serum CO2 >35 mmol/L. 3) reassessment after treatment step: oxygen saturation <90% on room air or usual O2, heart rate >120 beats/min. Each of the mentioned criteria, is allo- cated a score between 1-3, resulting in a total score between 0-16. 2.4. Outcomes Patients were followed up for 30 consecutive days for short- term adverse events including the need for intubation, non- invasive ventilation, myocardial infarction, readmission, and death from any cause. 2.5. Statistical analysis Data were analyzed using SPSS software version 26. The findings were reported as mean ± standard deviation or fre- quency (%). The best cut-off point for the scale in predicting the outcome of COPD patients was calculated using the area under the receiver operating characteristics curve (AUC). The screening performance characteristics of the scale (sensitiv- ity, specificity, positive and negative predictive values, and positive and negative likelihood ratios) were calculated us- ing the VassarStats calculator and reported with a 95% confi- dence interval. 3. Results 3.1. Baseline characteristics of studied cases In this study, 362 patients that met the inclusion and exclu- sion criteria were enrolled. The mean age of the patients was 65.55 ± 10.65 (6- 95) years, consisting of 58.0% male cases. The baseline characteristics of the patients are depicted in Table 1. Among them, 267 (73.8%) were in level 3 Emergency Severity Index (ESI) triage. The most frequent underlying comorbidities in this series were hypertension (59.2%), dia- betes mellitus (18.3%), and heart failure (11.5%). History of the patients revealed that 23 (6.4%) patients had CABG, 64 patients (17.7%) had an intervention for peripheral vascular disease, and 11 patients (3.1%) had intubation for respira- tory distress. Right axis deviation (30.4%) and cardiomegaly (38.7%) were the most frequent ECG and chest X-ray findings, respectively. 3.2. Outcomes Among the patients, 164 (45.3%) cases were discharged from ED, and 198 (54.7%) were admitted to the hospital. In this se- ries of patients, 136 (37.6%) cases experienced at least one of studied short-term adverse events (48 (13.3%) cases needed non-invasive ventilation, 31 (8.6%) cases were readmitted after ED discharge, 26 (7.2%) cases needed intubation, 20 (5.5%) cases experienced myocardial infarction, 6 (1.7) cases died within 30 days after discharge, 5 (1.4%) died after admis- sion). 3.3. Screening performance characteristics of OCRS The mean OCSD score of this series was 1.96 ± 2.39 (0 – 10). Figure 1 shows the frequency distribution of the OCSD score. The area under the curve of OCRS in predicting the outcome of COPD patients was 0.814 (95%CI: 0.766 – 0.862). The best cut-off point of the scale in predicting the outcome was 1.5. Table 2 summarizes the screening performance characteris- tics of OCRS. The sensitivity and specificity of the scale were 75.75% (95%CI: 69.6% – 81.42%) and 89.63% (95%CI: 83.67% – 93.66%), respectively. By employing this threshold in the present study, 48 (13.25%) of the patients would have unnec- essary hospitalization, and 17 (0.04%) would be discharged incorrectly. 4. Discussion In this study, the OCRS scale was used to predict the short- term adverse events of COPD exacerbation in patients pre- senting to ED, and it was found that the AUC value was greater than 0.8, indicating a high level of prediction accu- racy. Herein, the best cut-off value was detected as OCRS greater than 1, with the sensitivity and specificity of 75.75% and 89.63%, respectively. The present study’s short-term adverse events rate was es- timated as 38.01%. In the original study of OCRS valida- tion, 9.5% of the patients had experienced short-term ad- verse events (8). This rate in similar studies utilizing the OCRS scale was reported as 74% and 20.7%, both from Turkey This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index M. Alavi-Moghaddam et al. 4 Figure 1: Frequency distribution of the Ottawa Chronic obstructive pulmonary disease Risk Scale (OCRS) score in the studied popula- tion. Figure 2: The area under the receiver operating characteristic (ROC) curve (AUC) of the Ottawa Risk Scale in predicting the out- come of patients with chronic obstructive pulmonary disease (AUC= 0.814 (95%CI: 0.766 – 0.862)). (9, 10). This wide range in the rate of short-term adverse events from different centers could be due to the variation in the patients’ clinical condition, the level of facilities, and management strategies. However, the important point that has been consistently emphasized in these studies is a con- siderable number of short-term adverse events in the pa- tients discharged from the ED. This shows that an accurate and precise criterion for an error-free disposition decision is of great importance. Several tools have been introduced to help predict COPD ex- acerbation outcomes. BODE (body mass index, airflow ob- struction, dyspnea, and exercise capacity) is one of the most widely used indices for predicting disease severity and mor- tality. This index derived from an international collaboration in 2004 aimed at finding the risk factors of death in patients with COPD. The validation was performed on 625 patients, yielding an AUC of 0.74 (11). A study from France established “Score 2008” based on age, grade of dyspnea at steady state, and number of clinical signs of severity. The clinical accu- racy was assessed on 1824 patients with COPD admitted to the ED. Accordingly, they reported an AUC of 0.83 for Score 2008 to predict in-hospital mortality in COPD patients (12). In another study from the United Kingdom in 2012, the clin- ical admission data of 920 patients were investigated for the predictors of mortality in COPD patients. They reported that high Dyspnoea, Eosinopenia, Consolidation Acidaemia, and atrial Fibrillation (DECAF) score is a strong predictor of mor- tality with an AUC of 0.86 (13). While these multicomponent indices could successfully predict long-term mortality, they were not designed for other short-term adverse events. OCRS was designed to estimate the probability of short-term adverse events in patients with COPD exacerbation. In this study, we measured the AUC for OSCD and it was equal to 0.81, consistent with the previous reports (9, 10). Similar to the original OSCD study, the best cut-off value was above 1, with the sensitivity and specificity of 75.75% and 89.63%, re- spectively. By employing this threshold in the present study, 48 (13.25%) of the patients would have unnecessary hospi- talization, and 17 (0.04%) would be discharged incorrectly. Therefore, OCRS is a useful tool to predict the outcome of COPD exacerbation and ED physicians have approved and supported its applicability and effectiveness in ED. It should be noted that whether a patient is admitted or dis- charged from ED is not merely related to disease severity. Many non-medical factors can alter this decision, includ- ing hospital crowdedness, access to equipped ED, home care support, and patients’ preferences. However, OCRS can help ED clinicians to gauge their disposition decision according to their local practice. In a study on the applicability of the OCRS, 70.2% of the ED physicians confirmed and supported the effectiveness of OCRS to be used in ED for patients with COPD exacerbation (14). 5. Limitations The findings of this study should be viewed in the context of several limitations. First, this study has a small population. Studies with a larger statistical population are recommended to confirm and expand the findings of this study. It should also be noted that several of short-term adverse events were recorded to assess the performance of OCRS in predicting COPD outcomes. Moreover, the patients were not analyzed in a matched manner regarding the underlying diseases. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index 5 Archives of Academic Emergency Medicine. 2023; 11(1): e32 6. Conclusion The results of this study revealed the clinical validity of OCRS in predicting short-term adverse event in COPD patients pre- senting to the ED. The use of this scoring in the routine prac- tice of ED clinicians can lead to a reduction in unnecessary admissions and unsafe discharge of patients with COPD ex- acerbation. 7. Declarations 7.1. Acknowledgments Hereby, the staff of medical records department and treat- ment staff of Imam Hossein and Shohadaye Tajrish Hospitals are thanked for their cooperation in data gathering for this project. 7.2. Conflict of interest There is no conflict of interest to declare. 7.3. Fundings and supports None. 7.4. 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Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index Introduction Methods Results Discussion Limitations Conclusion Declarations References