Poor prognostic factors
Prognostic factors associated with a poor outcome (intensive care unit admission or death) include advanced age and the presence of comorbidities such as diabetes mellitus, hepatitis B infection, and heart disease.[11]Peiris JS, Chu CM, Cheng VC, et al. Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study. Lancet. 2003;361:1767-1772.
http://www.ncbi.nlm.nih.gov/pubmed/12781535?tool=bestpractice.com
[24]Lee N, Hui D, Wu A, et al. A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med. 2003;348:1986-1994.
http://www.nejm.org/doi/full/10.1056/NEJMoa030685
http://www.ncbi.nlm.nih.gov/pubmed/12682352?tool=bestpractice.com
[25]Booth CM, Matukas LM, Tomlinson GA, et al. Clinical features and short-term outcomes of 144 patients with SARS in the greater Toronto area. JAMA. 2003;289:2801-2809.
http://www.ncbi.nlm.nih.gov/pubmed/12734147?tool=bestpractice.com
[75]Tsui PT, Kwok ML, Yuen H, et al. Severe acute respiratory syndrome: clinical outcome and prognostic correlates. Emerg Infect Dis. 2003;9:1064-1069.
http://www.ncbi.nlm.nih.gov/pubmed/14519241?tool=bestpractice.com
[76]Chan JW, Ng CK, Chan YH, et al. Short term outcome and risk factors for adverse clinical outcomes in adults with severe acute respiratory syndrome (SARS). Thorax. 2003;58;686-689.
http://www.ncbi.nlm.nih.gov/pubmed/12885985?tool=bestpractice.com
An increased lactate dehydrogenase level, elevated C-reactive protein, and high neutrophil count on presentation as well as low counts of CD4 and CD8 lymphocytes are also associated with an independent increased risk of death.[24]Lee N, Hui D, Wu A, et al. A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med. 2003;348:1986-1994.
http://www.nejm.org/doi/full/10.1056/NEJMoa030685
http://www.ncbi.nlm.nih.gov/pubmed/12682352?tool=bestpractice.com
[75]Tsui PT, Kwok ML, Yuen H, et al. Severe acute respiratory syndrome: clinical outcome and prognostic correlates. Emerg Infect Dis. 2003;9:1064-1069.
http://www.ncbi.nlm.nih.gov/pubmed/14519241?tool=bestpractice.com
[77]Wong RS, Wu A, To KF, et al. Haematological manifestations in patients with severe acute respiratory syndrome: retrospective analysis. BMJ. 2003;326:1358-1362.
http://www.bmj.com/content/326/7403/1358
http://www.ncbi.nlm.nih.gov/pubmed/12816821?tool=bestpractice.com
Morbidity and mortality
Clinical deterioration requiring intubation and mechanical ventilation occurs at a median of 8 days after the onset of symptoms.[1]Christian MD, Poutanen SM, Loutfy MR, et al. Severe acute respiratory syndrome. Clin Infect Dis. 2004;38:1420-1427.
http://cid.oxfordjournals.org/content/38/10/1420.long
http://www.ncbi.nlm.nih.gov/pubmed/15156481?tool=bestpractice.com
Death is most often attributed to sepsis, acute respiratory distress syndrome, and multiple organ failure.[49]Lew TW, Kwek TK, Tai D, et al. Acute respiratory distress syndrome in critically ill patients with severe acute respiratory syndrome. JAMA. 2003;290:374-80.
http://www.ncbi.nlm.nih.gov/pubmed/12865379?tool=bestpractice.com
The case-fatality rate during the 2003 SARS outbreak was 9.6% and ranged between 0% and 40%.[2]World Health Organization: global alert and response (GAR). Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003. December 2003 [internet publication].
http://www.who.int/csr/sars/country/table2004_04_21/en
The mortality rate in patients over 65 years of age exceeds 50%.[2]World Health Organization: global alert and response (GAR). Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003. December 2003 [internet publication].
http://www.who.int/csr/sars/country/table2004_04_21/en
A residual decrease in lung function and persistent radiological abnormalities, as well as prolonged psychological sequelae and muscle weakness, are frequently observed in the survivors of SARS, although these tend to improve over time.[78]Chan KS, Zheng JP, Mok YW, et al. SARS: prognosis, outcome and sequelae. Respirology. 2003;8:S36-S40.
http://www.ncbi.nlm.nih.gov/pubmed/15018132?tool=bestpractice.com
Children (<12 years of age)
Children have a milder and shorter clinical course resembling that of the common cold.[38]Hon KL, Leung CW, Cheng WT, et al. Clinical presentations and outcome of severe acute respiratory syndrome in children. Lancet. 2003;361:1701-1703.
http://www.ncbi.nlm.nih.gov/pubmed/12767737?tool=bestpractice.com
[79]Chiu WK, Cheung PC, Ng KL, et al. Severe acute respiratory syndrome in children: experience in a regional hospital in Hong Kong. Pediatr Crit Care Med. 2003;4:279-283.
http://www.ncbi.nlm.nih.gov/pubmed/12831407?tool=bestpractice.com
[80]Bitnun A, Allen U, Heurter H, et al. Children hospitalized with severe acute respiratory syndrome-related illness in Toronto. Pediatrics. 2003;112:e261.
http://pediatrics.aappublications.org/content/112/4/e261.full
http://www.ncbi.nlm.nih.gov/pubmed/14523209?tool=bestpractice.com
Prognosis is thus more favourable than in adults, and no death has been reported in young children infected by SARS coronavirus.