Mortality Trends of Acute Respiratory Distress Syndrome in the United States from 1999 to 2013

Abstract

Rationale: Acute respiratory distress syndrome (ARDS) is an acute hypoxemic respiratory failure seen in critically ill patients after an inciting injury. The burden of ARDS mortality in the United States in recent years is not well characterized.

Objectives: In this study, we aimed to describe trends in the annual incidence of ARDS mortality in the United States from 1999 to 2013. We also describe demographic characteristics, geographic and seasonal trends, and other associated underlying causes of death in this population.

Methods: Data on all deceased U.S. residents are available through the Multiple Cause of Death (MCOD) database of the National Center for Health Statistics. ARDS-related deaths were identified in the MCOD database using International Classification of Diseases, 10th Revision.

Measurements and main results: Aggregate annual crude and age-adjusted mortality rates and mortality rate ratios were used to compare various demographic subpopulations. Over the 15-year period, the national ARDS-related age-adjusted mortality rate demonstrated an annual seasonal variation, peaking in winter. The annual rate decreased in a nonlinear fashion, with a plateau from 2010 to 2013. The ARDS-related age-adjusted mortality rate was 5.01 per 100,000 persons (95% confidence interval, 4.92-5.09) in 1999 and 2.82 per 100,000 persons (95% confidence interval, 2.76-2.88) in 2013. Males had a higher average ARDS-related mortality rate than did females. Asian/Pacific Islanders had the lowest average age-adjusted ARDS-related mortality rate, and black/African-American individuals, the highest.

Conclusions: National age-adjusted ARDS-related mortality rates decreased between 1999 and 2013 in the United States, yet still show relative racial and sex disparities. However, death certificates largely underestimate the overall mortality burden from ARDS when compared with studies of clinically ascertained cases.

Keywords: acute lung injury; acute respiratory distress syndrome; critical care; critical illness; epidemiology.

Figure 1.

Age-adjusted rates of acute respiratory distress syndrome (ARDS)–related mortality in the United States, 1999–2013. The red line displays mortality rates determined by a case definition of ARDS listed among any of the potentially 20 causes of death listed on a death record. The blue line displays mortality rates determined by ARDS listed as the principal underlying cause of death on a death record. The ribbons represent the 95% confidence limits of the estimates.

Figure 2.

Average annual crude rates of acute respiratory distress syndrome (ARDS)–related mortality by age group and race in the United States, 1999–2013. The ribbons represent the 95% confidence limits of the estimates.

Figure 3.

Average annual age-adjusted rates of acute respiratory distress syndrome–related mortality by state in the United States, 1999–2013.

Figure 4.

Annual proportions of acute respiratory distress syndrome (ARDS)–related deaths with other accompanying diagnoses in the United States, 1999–2013. The categories for associated diagnoses are not mutually exclusive and may be counted in multiple categories. For example, a death record with ARDS, a septicemia diagnosis, and a pneumonia diagnosis would be counted in both the Septicemia and the Influenza and Pneumonia groups.

Figure 5.

Age-adjusted mortality rates from acute respiratory causes in the United States, 1999–2013. The superimposed data point is extrapolated from published study results (9). It represents 33.2 deaths per 100,000, which was calculated by multiplying the 86.2 acute respiratory distress syndrome cases per 100,000 by the 38.5% in-hospital case fatality reported in the study.

Figure 6.

Comparison of crude death counts from acute respiratory causes as determined by death certificates and a clinical study in Olmsted County, Minnesota, 1999–2013. The red line represents in-hospital death counts of acute respiratory distress syndrome (ARDS) as reported in published study results (8). The other data were extracted for Olmsted County, Minnesota, using the Centers for Disease Control and Prevention’s (CDC) Wide-ranging Online Data for Epidemiologic Research (WONDER) Multiple Cause of Death (MCOD) dataset. Although ARDS defined in the MCOD database was included in the data request, the data did not meet the CDC’s minimal requirements of >10 counts to be reported.