Timing of Acute Respiratory Distress Syndrome Onset is Related to Patient Outcome

Background/Purpose: Acute respiratory distress syndrome (ARDS) is a major cause of mortality and morbidity in adult intensive care units. The relationship between the timing of ARDS onset and outcome is not well known. The objective of this study was to investigate the outcome of patients with late-onset ARDS during hospitalization. Methods: We prospectively enrolled patients who were intubated and fulfilled ARDS criteria in medical and surgical intensive care units in a tertiary referral medical center from December 1, 2004 to May 31, 2006. Those who developed ARDS more than 48 hours after hospital admission were categorized as late- onset ARDS; otherwise, they were defined as early-onset ARDS. We assessed the risk factors for hospital mortality using multivariate analysis and 90-day survival using Kaplan-Meier analysis between early- and late-onset ARDS, and between direct and indirect ARDS. Results: A total of 172 patients were included in the study. Overall mortality rate was 70%. Late-onset ARDS [odds ratio (OR): 3.06; 95% confidence interval (CI): 1.41 to 6.63; p = 0.005] and initial shock (OR: 8.20; 95% CI: 3.39-19.79; p < 0.001) were the independent risk factors for hospital mortality. Patients with late-onset ARDS had higher hospital mortality rate (83% vs. 60%; p = 0.002), longer duration of mechanical ventilation (27.0 ± 23.4 vs.14.6 ± 11.5 days; p < 0.001) and length of intensive care unit stay (25.5 ± 20.6 vs. 15.6 ± 13.6 days; p < 0.001) than patients with early-onset ARDS. The 90-day survival showed that both early-onset ARDS and direct ARDS were associated with better survival. Conclusion: Patients with late-onset ARDS are associated with poor prognosis and should be managed as high-risk patients.