What's the difference between SARS and ARDS?

Inpharma 1397 - 26 Jul 20031. Fowler RA, et al. Critically ill patients with severe acute respiratory syndrome.What’s the difference between JAMA: the Journal of the American Medical Association 290: 367-373, 16 Jul

2003.SARS and ARDS?2. Lew TWK, et al. Acute respiratory distress syndrome in critically ill patients

with severe acute respiratory syndrome. JAMA: the Journal of the AmericanIn critically ill patients, the clinical course of severe Medical Association 290: 374-380, 16 Jul 2003.

3. Rubenfeld GD. Is SARS just ARDS? JAMA: the Journal of the Americanacute respiratory syndrome (SARS) shares manyMedical Association 290: 397-399, 16 Jul 2003.characteristics with that of acute respiratory distress 800969062

syndrome (ARDS), according to two studies publishedrecently in JAMA.1;2

In the first study, the Toronto SARS Critical CareGroup retrospectively analysed data from 38 critically illadults with suspected or probable SARS who wereadmitted to ICUs in Toronto.1

This ICU group made up 19% of the patients withprobable or suspected SARS in Toronto area hospitals.The ICU patients were predominantly non-healthcareworkers and were older than the non-ICU patients, whowere predominantly healthcare workers. The ICU grouphad a high rate of prior comorbidity (50% of patients),especially diabetes mellitus (37%).

The diagnostic criteria for ARDS were met by 82% ofICU patients. Mechanical ventilation was required in76% of patients, cardiotonics or vasoactive agents in37%, and haemodialysis in 5%. The 28-day mortality ratewas 34% of patients and the 28-day mortality ormechanical ventilation rate was 50%. Mortality at 28days was associated with older age, diabetes mellitus,tachycardia at admission and an elevated creatine kinaselevel.

At 8 weeks’ follow-up, 52% of patients who requiredmechanical ventilation had died, "similar to the mortalityrate of a large unselected series of patients with ARDSrequiring mechanical ventilation", comment theresearchers. However, they note that, compared withinfluenza, "SARS is much more likely to progress from amild to a severe disease in young, otherwise healthyindividuals".

The second study was conducted by investigatorsfrom Singapore who reviewed all 46 probable cases ofSARS at the ICU of Tan Tock Seng Hospital, Singapore.2

These ICU cases made up 23% of probable SARScases at the hospital. Compared with non-ICU patients,ICU patients were significantly older and less likely to behealthcare workers. Furthermore, ICU patients weresignificantly more likely to have pre-existinghypertension and/or coronary artery disease than non-ICU patients.

The criteria for either ARDS or acute lung injury weremet by 45 patients. The 28-day and 13-week mortalityrates were 37% and 52.2% of ICU patients, respectively.Most patients had a protracted course of ARDS withcomplications and a high risk of mortality. "This patternis consistent with that reported in the literature, in whichmortality in late ARDS is related primarily to the degree ofother organ dysfunctions", comment the investigators.

In an editorial accompanying the two studies, DrGordon Rubenfeld from the University of Washington,Seattle, US, says that "in the ICU . . . SARS is essentiallyARDS plus intensified respiratory isolation".3 He adds thatthe development and implementation of treatments forARDS will be beneficial not only for patients with SARS,but also for patients with ARDS or acute lung injurycaused by far more common pathogens.

1

Inpharma 26 Jul 2003 No. 13971173-8324/10/1397-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved