Table 1.

Advantages and disadvantages of clinical trials

    often provides the strongest evidence in support of cause–effect relationships
    basis for clinical and public health policy
    minimize/eliminate bias and confounding
    many (if not most) research questions cannot be tested in trials because:
            exposure is fixed (e.g., gender)
            contrast between randomized groups is unobtainable (e.g., pre-ESRD patients unwilling to be randomly assigned to hemodialysis or peritoneal dialysis)
            the disease is rare; therefore, participants cannot be enrolled in a timely manner
            practical issues
            logistically complex
    innumerable ethical issues
    relevance rapidly diminishes in setting of
        secular trends
        rapidly evolving treatment