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Declining Mortality in Patients With Acute Respiratory Distress Syndrome

An Analysis of the Acute Respiratory Distress Syndrome Network Trials

Zhang, Zhongheng, MD1; Spieth, Peter Markus, MD2; Chiumello, Davide, MD3,4,5; Goyal, Hemant, MD6; Torres, ; Antoni, MD7; Laffey, John G., MD8; Hong, Yucai, MD1

doi: 10.1097/CCM.0000000000003499
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Objectives: There has been multiple advances in the management of acute respiratory distress syndrome, but the temporal trends in acute respiratory distress syndrome–related mortality are not well known. This study aimed to investigate the trends in mortality in acute respiratory distress syndrome patients over time and to explore the roles of daily fluid balance and ventilation variables in those patients.

Design: Secondary analysis of randomized controlled trials conducted by the Acute Respiratory Distress Syndrome Network from 1996 to 2013.

Setting: Multicenter study involving Acute Respiratory Distress Syndrome Network trials.

Patients: Patients with acute respiratory distress syndrome.

Interventions: None.

Measures and Main Results: Individual patient data from 5,159 acute respiratory distress syndrome patients (excluding the Late Steroid Rescue Study trial) were enrolled in this study. The crude mortality rate decreased from 35.4% (95% CI, 29.9–40.8%) in 1996 to 28.3% (95% CI, 22.0–34.7%) in 2013. By adjusting for the baseline Acute Physiology and Chronic Health Evaluation III, age, ICU type, and admission resource, patients enrolled from 2005 to 2010 (odds ratio, 0.61; 95% CI, 0.50–0.74) and those enrolled after 2010 (odds ratio, 0.73; 95% CI, 0.58–0.92) were associated with lower risk of death as compared to those enrolled before 2000. The effect of year on mortality decline disappeared after adjustment for daily fluid balance, positive end-expiratory pressure, tidal volume, and plateau pressure. There were significant trends of declines in daily fluid balance, tidal volume, and plateau pressure and an increase in positive end-expiratory pressure over the 17 years.

Conclusions: Our study shows an improvement in the acute respiratory distress syndrome-related mortality rate in the critically ill patients enrolled in the Acute Respiratory Distress Syndrome Network trials. The effect was probably mediated via decreased tidal volume, plateau pressure, and daily fluid balance and increased positive end-expiratory pressure.

1Department of Emergency Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.

2Department of Anesthesiology and Critical Care Medicine, University Hospital Dresden, Technische Universität Dresden, Germany.

3Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy.

4SC Anestesia e Rianimazione, Ospedale San Paolo – Polo Universitario, ASST Santi Paolo e Carlo, Milan, Italy.

5Centro ricerca cordinata di insufficienza respiratoria, Università degli Studi di Milan, Italy.

6Department of Internal Medicine, Mercer University School of Medicine, Macon, GA.

7Department of Pneumology, Institut Clinic del Tórax, Hospital Clinic of Barcelona - Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona - SGR 911- Ciber de Enfermedades Respiratorias (Ciberes) Barcelona, Spain.

8Critical Illness and Injury Research Centre, Keenan Research Centre for Biomedical Science of St Michael’s Hospital, Toronto, ON, Canada.

Drs. Zhang and Torres designed the study; Dr. Zhang performed data analysis; Drs. Spieth and Chiumello reviewed the article and helped revising the article; Drs. Spieth and Hong interpreted the results; Dr. Laffey helped interpreting the results and suggested in depth analysis. Dr. Zhang is the guarantor of the article, taking responsibility for the integrity of the work as a whole, from inception to published article.

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Supported, in part, by the public welfare research project of Zhejiang province (LGF18H150005) and Scientific research project of Zhejiang Education Commission (Y201737841).

The authors have disclosed that they do not have any potential conflicts of interest.

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