The Lipid Research Clinics Coronary Primary Prevention Trial. Results of 6 years of post-trial follow-up. The Lipid Research Clinics Investigators
BACKGROUND--Participants in the Lipid Research Clinics Coronary Primary
Prevention Trial, a randomized, cholesterol-lowering trial comparing
cholestyramine (N = 1907) vs placebo (N = 1899) treatment in 35- and
59-year-old asymptomatic hypercholesterolemic men, conducted between 1973
and 1983, were followed up annually from 1985 until 1989. Post-trial
treatment was not provided. METHODS--Eleven predefined hypotheses
pertaining to possible benefits and adverse effects of in-trial
cholestyramine treatment were tested by standard statistical comparisons of
the two original Coronary Primary Prevention Trial treatment groups
(cholestyramine and placebo). RESULTS--Similar increasing proportions of
cholestyramine and placebo used cholesterol-lowering drugs post-trial.
After 13.4 years of in-trial plus post-trial follow-up, there were 13 (143
vs 156) fewer deaths in the cholestyramine group than in the placebo group.
Although not statistically significant, the mortality hazard ratio (0.89)
was similar to that in other cholesterol-lowering trials. This trend, a
result of reduced coronary heart disease mortality, occurred despite a
post-trial narrowing of the in-trial cholestyramine-placebo difference in
coronary heart disease incidence from 32 (155 vs 187) to 16 (268 vs 284).
The cholestyramine and placebo groups had similar 13.4-year mortality rates
from cancer, other medical causes, and trauma and similar cancer incidence
rates. However, 13.4-year incidences of benign colorectal tumors (50 vs
34), cancer of the buccal cavity and pharynx (eight vs two), gallbladder
disease (68 vs 53), and gallbladder surgery (58 vs 40) were
nonsignificantly increased in the cholestyramine group.
CONCLUSION--Overall, 6 years of post-Coronary Primary Prevention Trial
follow-up have not provided conclusive evidence of benefit or long-term
toxicity of cholestyramine treatment beyond that evident at the cessation
of the trial.
