Overview of ethical issues in clinical studies.

Research in human subjects should be conducted only if the rights and welfare of the participants are protected. Prospective study subjects must be given adequate information about all aspects of a study so that they can make a rationally exercised decision about participation; coercive techniques to solicit participants should not be used. Research in humans may be classified in one of three categories: A. Research on treatment of existing conditions; B. Research on preventive measures; and C. Research other than for treatment or prevention. Different concerns and aspects of informed consent assume particular importance in each category. In research on the treatment of existing conditions, untreated or placebo-treated control groups are rarely justified if the condition is irreversible. In research on preventive methods prospective subjects should be informed of the likelihood of receiving an ineffective treatment, if one or more placebo groups are included. A randomized clinical trial is usually the best design for studies of preventive methods. Nonrandomized designs, that are feasible and statistically valid, may be employed in order to avoid depriving some subjects from receiving effective preventive methods. In social or behavioral research, confidentiality of collected information and privacy of the subject are essential considerations.