Meta-Analysis: Convalescent Blood Products for Spanish Influenza Pneumonia: A Future H5N1 Treatment?

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   Figure 1. Flow diagram of trial identification and selection.

   *Most of these studies were excluded on the basis of multiple criteria.
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   Figure 2. Absolute risk differences in mortality among patients treated with convalescent blood products and controls.

   Results favor treatment with convalescent blood products (z = 7.1; P < 0.001), and there was no statistical evidence of large heterogeneity (Q = 7.0; I² = 29.3%; P = 0.22). The pooled estimate should be interpreted with caution and should not be generalized to other strains of virulent influenza without further study. Percentages have been rounded to the nearest whole integer. *In 2 studies with low mortality rates in the treatment group, the majority of patients were treated within 48 hours after pneumonia complicating influenza was diagnosed (18, 23, 24). McGuire and Redden (23, 24) reported a range of mortality rates of 30% to 60% among controls, and 30% was used in the analysis.
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   Figure 3. Absolute risk difference in mortality among patients who received early versus late treatment with convalescent blood products.

   Results favor treatment with convalescent blood products (z = 6.50; P < 0.001), and there was no statistical evidence of heterogeneity (Q = 2.76; I² = 0%; P = 0.43). The pooled estimate should be interpreted with caution and should not be generalized to other strains of virulent influenza without further study. Percentages have been rounded to the nearest whole integer. *The treatment day of a fatal case could not be determined and was excluded from analysis of early versus late treatment (19, 20).