Long-term outcome of acute respiratory distress syndrome caused by severe acute respiratory syndrome (SARS): an observational study

Abstract

Objective: We examined long-term outcome of pulmonary function, exercise capacity and health-related quality of life (HRQoL) in patients with acute respiratory distress syndrome (ARDS) caused by severe acute respiratory syndrome (SARS).

Methods: 59 critically ill patients with ARDS caused by SARS between March and July 2003 were studied prospectively and followed up for 1 year. Thirty-six underwent pulmonary function testing and a 6-minute walk test, and 35 underwent HRQoL evaluation by Short Form-36 questionnaire at 3, 6, and 12 months after illness onset.

Results: Mean age was 47 (SD, 15.7) years. Median APACHE II score was 10 (interquartile range [IQR], 7-12). Only 47% required invasive mechanical ventilation. Median admission and worst PaO2/FIO2 ratio were 142 (IQR, 94-177) mmHg and 86 (IQR, 66-122) mmHg, respectively. Median stay in ICU and hospital were 9 (IQR, 5-20) and 31 (IQR, 20-54) days, respectively. Mortality was 24% at hospital discharge and at 1 year. Mean lung volumes and spirometric measurements were nearly normal by 6 months. Except for diffusion capacity adjusted for haemoglobin concentration (DLCO) measured at 12 months, there was no significant difference in pulmonary function measurement between those who had mechanical ventilation and those who did not. The 6-minute walk distance (6MWD) improved from 3 to 6 months, with no further significant change. Younger patients had near normal HRQoL by 6 months. Those aged over 40 years had impaired HRQoL at multiple domains even at 12 months. At 12 months, forced expiratory volume in 1 second, forced vital capacity and 6MWD correlated significantly with multiple SF-36 domain scores. DLCO correlated significantly only with domain scores reflecting physical function.

Conclusions: The mortality of SARS-related ARDS is similar to the mortality of ARDS from other causes. A substantial number of patients with SARS-related ARDS survived without receiving mechanical ventilation. Patients had good recovery of pulmonary function and HRQoL.