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Edward J Gracely, PhD
Medical College of Pennsylvania Philadelphia

JAMA. 1993;270(13):1543.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

To the Editor.

—Both Rogers et al¹ and von Reyn et al² in their investigations of human immunodeficiency virus (HIV) transmission by infected physicians make implausible statistical claims about the maximum likely true rate of transmission.

Rogers et al, based on the absence of HIV transmission in 369 person-hours of surgical exposure, regard it as unlikely that transmission occurs more often than once per 1000 person-hours of such exposure. The specific power to detect more than once per 1000 person-hours is given as 91% in the text, and the general claim that such a rate is unlikely is repeated in the abstract.

On its face, it is difficult to see how an event occurring once in 1000 hours could have even a 50% probability of occurring in 369 hours, let alone a 91% probability; yet, that is the implication of the authors' assertion.

Assuming the 369 person-hours to . . . [Full Text PDF of this Article]

Footnotes
Edited by Drummond Rennie, MD, Deputy Editor (West), and Margaret A. Winker, MD, Senior Editor.

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