Trial Information

Respiratory Ancillary Study (RAS) to SELECT

BACKGROUND:

Observational epidemiologic studies provide compelling evidence suggesting that high
antioxidant intake is associated with reduced risk of chronic obstructive pulmonary disease
(COPD) and increased lung function.

DESIGN NARRATIVE:

The purpose of this study is two-fold. First, the study will longitudinally test whether: 1)
the decrease in FEV1 over 3 years is lower among men receiving daily supplementation with
200 µg selenium compared to men receiving placebo; and 2) the decrease in FEV1 over 3 years
is lower among men receiving daily supplementation with both 200 µg selenium and 400 mg
vitamin E compared to men receiving placebo. Second, the study will cross-sectionally test,
at 3 years post-randomization, whether: 1) FEV1 is higher among men receiving daily
supplementation with 200 µg selenium and 400 mg vitamin E compared to men receiving placebo;
and 2) FEV1 is higher among men receiving daily supplementation with 200 µg selenium
compared to men receiving placebo.

The primary outcome of this study will be pulmonary function decline, which will be studied
in 3,000 Selenium and Vitamin E Cancer Prevention Trial (SELECT) men at 18 SELECT sites.

The key secondary outcome will be COPD and asthma occurrence in the 35,000 men of the SELECT
trial. Data on outcome occurrence will be updated at each biannual visit.

This study is an ancillary to the SELECT study (selenium and vitamin E supplements being
studied for effects on prostate cancer prevention), which withdrew supplements from all
participants in October 2008 due to no effect on prostate cancer. Data collection continues
in both SELECT and in this study in the post-supplementation period until researchers have
completed pulmonary function testing (three measurements in 3 years) on all participants.
Ultimately, the trial analysis will examine whether treatment affected the endpoint in the
intervention period, and whether the effect is attenuated in the post-supplementation
period.