Epidemiological and Clinical Profiles of Patients with Acute Respiratory Distress Syndrome Admitted to Medical Intensive Care in Qatar: A Retrospective Analysis of the Data Registry for the Year 2015

Background: Although acute respiratory distress syndrome (ARDS) is a common reason for admission to intensive care units, limited information is available about the epidemiological and clinical characteristics of these patients in Middle Eastern countries. Qatar is a high per capita income country with a large multinational expatriate population. Hamad General Hospital is our main tertiary referral center with the largest medical intensive care unit (MICU). Method: A retrospective cross-sectional study was conducted to extract data from the MICU registry for 101 patients aged >14 years who were admitted with ARDS from January 2015 to December 2015. Results: In 2015, a total of 101 (14.8%) of 682 patients admitted to MICU were diagnosed with ARDS. Males comprised 71.3% and females 28.7%. The mean age of the study population was 44.96 ± 17.97 years. Community-acquired bacterial and viral pneumonia were the most common reasons for ARDS. Crude mortality rate was 35%. The mean age of survivors was 42.09 ± 13.58 years compared with 50.36 ± 16.84 years of non-survivors (p = 0.008). Mortality was associated with increasing age, the Acute Physiologic Assessment and Chronic Health Evaluation II severity score, lower P/F ratio, higher Murray's score, higher PCO2, lower pH, and circulatory support with vasopressors. Preexisting comorbidities did not contribute to high mortality. No difference in mortality was noted with higher versus lower positive end expiratory pressure. The prone position was used in 8% of the cases. Twenty-seven (27%) patients had undergone salvage therapy with extracorporeal membrane oxygenation (ECMO) that resulted in a survival rate of 44%. ARDS was associated with acute renal failure requiring dialysis in 28.7% of the cases, pneumothoraces in 4%, ventilator-associated pneumonia in 7.9%, and central line-associated bloodstream infection in 2%. ARDS led to a prolonged length of stay compared with the average length of stay in MICU. Conclusion: Community-acquired bacterial and viral pneumonia were the most common causes of ARDS at our center. Critical care outcome correlated with the severity of the disease. ECMO was used as salvage therapy in our center.

with extracorporeal membrane oxygenation (ECMO) that resulted in a survival rate of 44%. ARDS was associated with acute renal failure requiring dialysis in 28.7% of the cases, pneumothoraces in 4%, ventilator-associated pneumonia in 7.9%, and central line-associated bloodstream infection in 2%. ARDS led to a prolonged length of stay compared with the average length of stay in MICU. Conclusion: Community-acquired bacterial and viral pneumonia were the most common causes of ARDS at our center. Critical care outcome correlated with the severity of the disease. ECMO was used as salvage therapy in our center.
Keywords: acute respiratory distress syndrome, pneumonia, extracorporeal membrane oxygenation BACKGROUND Epidemiological research in acute respiratory distress syndrome (ARDS) is important to understand the variability in disease presentations, patterns of care, and outcome in different patient populations. 1 Limited data is available regarding the epidemiological and clinical profile of ARDS patients in Middle Eastern countries. ARDS is a common cause of admission to critical care units. It causes significant morbidity and still carries high mortality. 2 -4 A specialized data registry system ensures the uniformity of diagnostic criteria and the detailed documentation of studied variables. Registry data is informative in the study of differences in etiological factors, population characteristics, patterns of clinical care, and resource utilization in different populations. The incidence, clinical course, morbidity, and outcome of ARDS in medical patients have not been previously studied in Qatar, a country that is mostly composed of a multinational expatriate population. Furthermore, the introduction of extracorporeal membrane oxygenation (ECMO) service in 2014 provided a unique perspective of studying the utility of this modality in ARDS management.

MATERIALS AND METHODS
This investigation was a retrospective observational study utilizing the medical intensive care unit (MICU) one-year (2015) registry data at the main tertiary hospital in Qatar. The institution's Medical Research Center approved this study.

Inclusion criteria
All ARDS patients aged .14 years admitted to MICU during the study period. Diagnosis of ARDS was based on the Berlin definition for ARDS, 2 which includes the following:

DISCUSSION
Epidemiological registries in ARDS provide valuable sources of information that can improve understanding of the disease, patterns of care, and variables affecting outcome. 1 The current study focused on single-year (2015) data when specific data collection for auditing was planned, and cases were tracked from admission to discharge. In the current study, 14.8% of all ICU admissions were for ARDS, which is consistent with other published data where incidence varies from 2.5% to 19%. 3 -5 A male predominance of 72% in our study is consistent with that reported in other international studies 6 and is also explained by the overall composition of the Qatari population, which has a There was no statistically significant difference in the outcome of ARDS patients with risk factors and comorbidities when compared with those without any risk factors or comorbidities. On the other hand, as shown in other studies, 9 increasing mean age, higher APACHE II severity score, lower P/F ratio, higher Murray's score, higher PCO 2 , lower pH, higher procalcitonin levels, and VAP, were significantly associated with increased crude mortality. 10 Both the mode of ventilation and higher PEEP were not associated with any mortality benefit in this study. Overall, mean TV was higher than that calculated by the predicted body weight. This has been observed in other studies as well. This observation emphasizes the need to review local data to confirm that there is no disconnect between the theoretical and practical application of evidence-based practices in the ICU. 11 Although the prone position is a standard therapy for severe ARDS with mortality benefits, 12 it was performed in only 8% of the cases in 2015. This was likely because of inadequate training and experience of the team in the use of prone position for ARDS in 2015. This highlights the crucial role of education, training, and experience of the respiratory failure care team members in the use of the prone position in ARDS patients. After this observation, multiple educational workshops have been conducted for all ICU team members, and the prone position has become a standard step in the management of appropriate ARDS patients. The predominant cause for admission in our study was community-acquired pneumonia in 69% of patients.
Patients with community-acquired viral pneumonia had an overall survival rate of 85%, which is similar to 75% survival with ECMO reported in another study. 13 Although case series have reported ECMO use as salvage therapy for acute respiratory failure in pulmonary tuberculosis (TB), 14 16 Our study showed that the overall intensive care outcome in VV ECMO in severe ARDS at our center was 44% in 2015, and the Extracorporeal Life Support Organization international report indicates a survival rate of 57% in the corresponding year. 17 This study emphasizes the utility of registry data at an individual center to compare the practice with international standards. The benefits of this objective data also help evaluate practices that otherwise may not be obvious. This was apparent in our objective data of TV use, which was higher than recommended. Also, prone position data helped us improve our overall practice in this area. Registry data is also useful in securing more resources from local leadership with a relatively major impact on patient care improvement. The limitation of this study is that being a descriptive retrospective study, where part of the data is collected from the medical records, the significance of the observed differences between various clinical variables among survivors and nonsurvivors could not be assessed. The study did not specifically explore the variability among ARDS secondary to different etiologies. Also, the registry data was limited to ICU stay, and no medium or longterm outcome after ICU discharge was evaluated.

CONCLUSION
Specific ARDS registries provide valuable information on the epidemiology of the disease; factors that affect the outcome; and adherence to standardized, evidence-based care. In our center, bacterial and viral pneumonia remain the dominant etiologies of ARDS. The outcome of ARDS patients is primarily influenced by the etiology and severity of the disease. Despite the well-recognized importance of low TV strategy and prone position in ARDS, the mean TV used was higher than recommended, and the utilization of prone position remains low. Local data exploration by adopting registries is a useful way to explore the regional differences in ARDS epidemiology and routine clinical care, which may help improve overall outcomes in ARDS patients. This study demonstrates ARDS as an important healthcare problem in Qatar, which requires healthcare authorities to develop preventive strategies and advance its management.

Consent for publication
Not applicable.

Availability of data and material
The datasets generated and/or analyzed during the current study are not publicly available (as they are part of the data registry of the intensive care unit and are not available externally) but are available from the corresponding author on reasonable request.