United Christian Hospital, Hong Kong
Correspondence to: Chung-Ming Chu, MD, FCCP, United Christian Hospital, Hong Kong, PRC
We read with interest the article in CHEST by Chiou et al (July 2005)1and offer the following comments. The ribavirin-treated patients had higher lactate dehydrogenase levels, a well-known adverse prognostic factor in severe acute respiratory syndrome (SARS). The nonsignificantly higher mortality could be due to the more severe disease in this group. Viral load, another important predictor of mortality, was not available.2 Moreover, Figure 1 seemed inaccurate: the survival in ribavirin-treated patients should be 0.88 at day 30 (5 of 44 patients died) instead of 0.71.
Classifying the ribavirin-treated patients into hypoxemic and nonhypoxemic subgroups (Table 2) and attributing the higher mortality in the hypoxemic subgroup to ribavirin was problematic, as both subgroups were treated with an identical protocol of ribavirin. From the data presented, a more likely explanation for the more severe drop in hemoglobin in the hypoxemic subgroup was that they had more severe disease. The survival curves in Figure 4 also appeared inaccurate: the survival in patients with drop in hemoglobin > 2 g/dL should be 0.69 (5 of 16 patients died) instead of 0.45. Hence, the result of the log-rank test (p = 0.007) needs to be justified.
Only factors that were potentially associated with hypoxemia were analyzed in Table 2. No univariate or multivariate analyses on factors related to death were reported. The conclusion that hemoglobin level was the only factor associated with death was not supported by the data presented.
In Figure 6, the shaded triangles were supposed to represent the hemoglobin of patients who were hypoxemic and had received ribavirin. There were 22 triangles, but there should only be 17 patients. In addition, expressing the survival of individual patients by proportion (y-axis) is difficult to understand.
Therefore, there is no convincing evidence that ribavirin has contributed to a life-threatening drop in hemoglobin or mortality in this report. As of today, three independent studies3–5 have shown ribavirin to have in vitro activities against SARS-coronavirus, alone or in combination with other agents. Ribavirin should be tested in future randomized controlled studies in combination with other potential antiviral agents for SARS.
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