Limitations
RECRUITMENT
This study has some limitations, including the fact that patient accrual fell below the intended 515 due to an unexpectedly high proportion of ineligible patients, the elderly age of the patient population with accompanying comorbidities and medication, and the proposed trial duration. Furthermore, trial funding was withdrawn in 2010, resulting in the decision to end recruitment and treatment in 2011. Consequently, study participants received considerably less selenium and vitamin E than intended, and 245 fewer patients than required were recruited; thus, these analyses are underpowered.