From the Department of Medicine, Section of Critical Care, Banner Good Samaritan Medical Center.
Correspondence to: Robert A. Raschke, MD, Department of Medicine, Section of Critical Care, Banner Good Samaritan Medical Center, 1111 E McDowell Rd, Phoenix, AZ 85006; e-mail: firstname.lastname@example.org
Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.
I am surprised by the published conclusions of Hung et al1 in a recent issue of CHEST (August 2013). The authors’ stated methods are not adequate to support their conclusion that hyperimmune IV immunoglobulin (H-IVIG) benefits mortality if given within 5 days to patients with severe 2009 influenza A(H1N1) infection.
The primary outcome analysis of 34 patients presented in Table 1 of the study1 shows that five patients who received H-IVIG died, and four control subjects died. The authors subsequently performed a subgroup analysis of 22 patients who received treatment within 5 days of symptom onset. All five of the H-IVIG fatalities were excluded from this analysis, but all four of the control subjects’ deaths were retained. This is not explicitly explained by the authors but can be seen by comparing survival data in Tables 1 and 2.1 There is no mention of any plan to perform this subgroup analysis in the Materials and Methods section; therefore, there is no guarantee that this subgroup was not specifically formulated to elicit a presupposed conclusion. This is an excellent example of why unplanned subgroup analysis should not be acceptable as a basis for scientific conclusions.
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