Skip to main content
A New Surrogate Variable for Erectile Dysfunction Status in the Massachusetts Male Aging Study
Journal of Clinical Epidemiology
  • Kenneth Kleinman, University of Massachusetts Amherst
  • Henry Feldman
  • Catherine Johannes
  • Carol Derby
  • John McKinlay
Publication Date
Erectile dysfunction (ED) is the subject of a vast clinical literature, but little information has been gathered from random samples of the general public. The Massachusetts Male Aging Study (MMAS) addressed this important aspect of men's health. The MMAS was conducted in two waves, with baseline data collection in 1987–1989 and follow-up in 1995–1997. Subsequent to the baseline MMAS survey, a consensus developed that subjective measures are optimal for defining ED. Unfortunately, the baseline questionnaire did not ask subjects directly about their erectile functioning. Thus, we previously assigned the MMAS subjects a degree of impotence at baseline using a series of related questions, employing a discriminant formula constructed from a separate sample of urology clinic patients. At follow-up the men classified themselves directly in addition to answering the original series of related questions. In the present article, we report the results of a new discriminant function, based on the MMAS men at follow-up. We also compare the two methods and discuss our reasons for preferring the internally calibrated method.

© 2000. This manuscript version is made available under the CC-BY-NC-ND 4.0 license. Published by Elsevier:

Citation Information
Kenneth Kleinman, Henry Feldman, Catherine Johannes, Carol Derby, et al.. "A New Surrogate Variable for Erectile Dysfunction Status in the Massachusetts Male Aging Study" Journal of Clinical Epidemiology Vol. 53 Iss. 1 (2000)
Available at: