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LETTER TO THE EDITOR

On the Hazard Ratios and Corresponding Confidence Intervals That Appear in Basran et al. (2006)

United States Food and Drug Administration; mark.rothmann{at}fda.hhs.gov

To the Editor:

We would like to draw your attention to the hazard ratios and corresponding confidence intervals that appear in Basran et al.’s article (1). We would like clarification from the authors on the estimates and confidence intervals for the hazard ratios, and the units of the predictors that appear in Tables 2 and 3 of the paper. Standard confidence intervals for hazard ratios are such that the hazard ratio estimate equals the geometric mean of the upper and lower limits of the confidence interval (easily computed as the square root of the product of the upper and lower limits of the confidence interval). However, the estimates of most hazard ratios presented in Tables 2 and 3 are inexplicably much less than the geometric mean of the upper and lower limits of the confidence interval. From the data presented in the article we cannot infer whether it is the confidence intervals or the estimates that are incorrect, or whether both are incorrect.

Also, to interpret correctly the hazard ratio estimates for the covariates provided in Tables 2 and 3, it is important to specify the units in which those covariates were measured and how the covariates were used in the analysis. This was not done for the vast majority of the covariates. Important information about whether and how each covariate was discretized, dichotomized, or used as a continuous covariate (with the units specified) in the analysis should be provided.

REFERENCE

1. Basran S, Frumento RJ, Cohen A, et al. The association between duration of storage of transfused red blood cells and morbidity and mortality after reoperative cardiac surgery. Anesth Analg 2006;103: 15–20.[Abstract/Free Full Text]

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				S. Basran, R. J. Frumento, A. Cohen, S. Lee, Y. Du, E. Nishanian, H. S. Kaplan, M. Stafford-Smith, and E. Bennett-Guerrero On the Hazard Ratios and Corresponding Confidence Intervals That Appear in Basran et al. (2006) Anesth. Analg., June 1, 2007; 104(6): 1597 - 1597. [Full Text] [PDF]

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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Rothmann, M. Articles by Ng, T.-H. Search for Related Content PubMed Articles by Rothmann, M. Articles by Ng, T.-H.