Uncertainty intervals based on deleting data are not useful.

When analyzing the ELISA data, we found that the serum SAA concentrations were greatly increased in both the SARS and non-SARS patient groups. The mean serum SAA concentrations of the SARS and non-SARS patient groups were 40-and 85-fold higher than the upper limit of the reference interval (Ͻ10 mg/L), respectively. Consistent with the SELDI data, the serum SAA concentrations were significantly lower in the SARS patient group (P Ͻ0.005; Table 1). The results from both the SELDI ProteinChip assays and ELISA indicated that serum SAA by itself was not useful in differentiating the SARS patients from the non-SARS patients who were suspected cases during the SARS outbreak period. Because serum SAA was increased in the SARS patients, however , we could not exclude the possibility that it could be used in combination with other serum markers to develop a classification model for SARS diagnosis. Serum SAA is an acute-phase reac-tant (7) that has been shown to increase in various types of viral and bacterial infections (8). Regardless of the types of infection, serum SAA concentrations can increase up to 2000 mg/L. The degree of increase may reflect only the severity of the illness and does not indicate the cause. In the SARS patient group, we found that the SAA peaks and the serum concentration correlated significantly with the serum C-reactive protein concentration (Table 1), as in other infectious diseases (8). This suggests that the increases in serum SAA were caused mainly by the in-flammatory response to SARS infection. In conclusion, data from both the SELDI ProteinChip profiling study and an ELISA study do not support the contention that increased serum SAA is indicative for SARS. In contrast , our results strongly suggest that the serum SAA concentration is not useful in differentiating the SARS patients from the non-SARS patients who are suspected cases during the SARS outbreak period. al. Proteomic fingerprints for potential application to early diagnosis of severe acute respiratory syndrome. Humeny A, et al. Serum protein profiling by SELDI mass spectrometry: detection of multiple variants of serum amyloid ␣ in renal cancer patients. Kwan TL, et al. Protein chip array profiling analysis in patients with severe acute respiratory syndrome identified serum amyloid A protein as a biomarker potentially useful in monitoring the extent of pneumonia. Tong YK, et al. Serial analysis of plasma pro-teomic signatures in pediatric patients with severe acute respiratory syndrome and correlation with viral load. …