Predictive model of diagnosing probable cases of severe acute respiratory syndrome in febrile patients with exposure risk

Abstract

Study objective: Since the World Health Organization issued a global alert about severe acute respiratory syndrome (SARS) on March 12, 2003, the illness has become a major public health challenge worldwide. The objective of this study is to identify the clinical risk factors of SARS and to develop a scoring system for early diagnosis.

Methods: The detailed clinical data of all patients presenting to the emergency department (ED) with a temperature higher than 38.0 degrees C (100.3 degrees F), documented at home or at the ED, and risks of exposure to SARS within 14 days were assessed. The diagnosis of probable SARS was made according to the definition of the Centers for Disease Control and Prevention. Items with significant differences among symptoms, signs, and laboratory tests on presentation between SARS and non-SARS groups were determined and used to develop the scoring system.

Results: Seventy patients were enrolled and 8 were diagnosed as probably having SARS. None of the initially discharged patients or their relatives developed SARS. Compared with the non-SARS group, the SARS group was younger (33.9+/-15.9 years versus 44+/-9.8 years; P=.02), had a higher percentage of fever prolonged more than 5 days (87.5% versus 6.5%; P<.01), myalgia (75% versus 27.4%; P=.01), and diarrhea (50% versus 9.7%; P=.02); had less occurrence of cough before or during fever (0% versus 64.5%; P=.01); and had lower absolute lymphocyte (0.9+/-0.3x10(9)/L versus 1.5+/-1.1x10(9)/L; P<.01) and platelet counts (144.1+/-36.3x10(9)/L versus 211.6+/-78.8x10(9)/L; P=.02). A 4-item symptom score based on the presence of cough before or concomitant with fever, myalgia, diarrhea, and rhinorrhea or sore throat detects SARS with 100% sensitivity and 75.9% specificity; a 6-item clinical score based on lymphopenia (<1.0x10(9)/L), thrombocytopenia (<150x10(9)/L) and the 4 symptom items detects SARS with 100% sensitivity and 86.3% specificity.

Conclusion: Certain symptoms and laboratory tests indicate higher risk of febrile probable SARS. In nonendemic areas, the febrile patients with recent contact with SARS or travel history to endemic areas could be screened for the probability of SARS by the use of clinical and symptom scores.