Objective: To explore the risk factors related to severe cases of severe acute respiratory syndrome (SARS) in order to find the early warning signs of deterioration of this disease.
Methods: Three hundred and fifty-five patients with severe SARS and 841 patients with regular SARS from Beijing were studied.
Results: Patients with elder age or with comorbid conditions were more likely to develop into severe cases. Data also showed the following characteristics in those severe cases: sustained fever, tachycardia (pulse rate being over 100 per minute), persistent decrease in lymphocytes (< 0.9 x 10(9)/L), increase in neutrophils (> 7.1 x 10(9)/L, 80%), and rapid changes in abnormal chest X-ray. The Cox proportional hazard multi-variable stepwise analysis showed the prediction model of severe SARS included age, comorbid disease, body temperature being still abnormal after 2 days of hospitalization, neutrophil percentage began to increase steadily to more than 80% after 3 days of hospitalization, counts of lymphocytes persisted < 0.9 x 10(9)/L after 4 days of hospitalization.
Conclusions: According to patient's age, comorbid conditions, one can effectively predict the development of the severe SARS by closely monitoring temperature, pulse rate, the counts of lymphocytes and percent of neutrophils.