We are grateful for the opportunity to address the concerns that may have arisen from the results of the case–control study of Hoes and colleagues , which was published shortly after our review appeared . The conclusion of this study suggested an association between β-blocker therapy and sudden death. Our review advocated the use of β-blockers to reduce the risk for sudden death.
Case-control studies are designed to detect possible associations, whereas randomized trials are needed to show the effect of an intervention. In the study of Hoes and colleagues , case-patients were probably prescribed a β-blocker more often than were controls because their physicians considered them to have an increased risk for sudden death. Although the authors used several methods to limit this problem, any study that does not use random treatment assignments is subject to potential bias.