Clinical and epidemiological predictors of transmission in Severe Acute Respiratory Syndrome (SARS).

BACKGROUND: Only a minority of probable SARS cases caused transmission. We assess if any epidemiological or clinical factors in SARS index patients were associated with increased probability of transmission. METHODS: We used epidemiological and clinical data on probable SARS patients admitted to Tan Tock Seng Hospital. Using a case-control approach, index patients who had probable SARS who subsequently transmitted the disease to at least one other patient were analysed as "cases" against patients with no transmission as "controls", using multivariate logistic regression analysis. RESULTS: 98 index patients were available for analysis (22 with transmission, 76 with no transmission). Covariates positively associated with transmission in univariate analysis at p 650 IU/L (OR 6.4, 23.8 and 4.7 respectively). CONCLUSION: Clinical and epidemiological factors can help us to explain why transmission was observed in some instances but not in others