Physicians’ Health Study

The Physicians’ Health Study (PHS) is a randomized, double-blind, placebo-controlled trial that was initially designed as a cohort study to test the effect of two medications: (1) the effect of aspirin on mortality due to cardiovascular disease and (2) the effect of betacarotene on reducing the incidence of cancer. The initial planning for the PHS began in 1978, with Phase One (PHS-I) beginning in 1982 and ending in 1995. Phase Two of the cohort study (PHS-II) began in 1997 and is expected to conclude in 2007. This entry provides a general overview of the two phases of PHS and briefly discusses the major findings from PHS-I.