This Article  • References  • Full text PDF  • Reply to article  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Social Bookmarking   What's this?

Robert P. Hirsch, PhD
Bethesda, Md

Bernard Schwartz, MD, PhD
Boston

Arch Ophthalmol. 1987;105(2):166-167.

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

In Reply.

—We agree with Radvanovi et al that the choice of a reference group is of critical importance in epidemiologic studies such as the one we reported in 1983¹ and the one more recently published by Cvetkovi et al.² In choosing a reference group with which to compare survival of persons who have undergone cataract extracton, we recognized that the hypothesis of interest to us was that "cataracts result from systemic processes that are associated with aging" and that such an association should be reflected in survival. To test that hypothesis, "we searched for a reference group that would provide comparability in factors influencing mortality" to avoid selection biases. Comparison with the general population was considered inadequate because persons undergoing cataract extraction at the New England Medical Center, Boston, are likely to differ from that potential comparison group in a number of ways that are expected to influence . . . [Full Text PDF of this Article]

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?