Lessons from TGN1412 and TARGET: implications for observational studies and meta-analysis.

Two very different studies are examined: the first, a very large trial in osteoarthritis (the so-called TARGET study) and the second a very small 'first-in-man' study of the monoclonal antibody TGN1412. In each trial the unbiased estimate of the treatment effect is not efficient and in con sequence the efficient estimate is not unbiased. In the case of the large trial it seems reasonable that unbiased estimation is desirable but in the case of the small trial it leads to absurd conclusions. These two cases are examined in detail and some general lessons for the analysis of clinical trials and observational studies and collections of studies are drawn. (c) 2008 John Wiley & Sons, Ltd.