strategy, and patients must be randomized to receive or not receive the plasmapheresis. Finally, the article must report clinically important outcomes, such as deterioration in renal function. You are familiar with the software program "Grateful Med" and use it for your search. The program provides a listing of Medical subject (MeSH) headings, and you quickly find that "lupus nephritis" is one such heading and "plasmapheresis" another. You add a methodological term that will restrict your results to high quality studies, "randomized controlled trial (PT)" (PT stands for publication type). The search, which you restrict to English-language articles, yields a total of three papers. One is a trial of prednisone and cyclophosphamide [1] ; a second examines the effect of plasmapheresis on risk of infection [2] . The third citation, which describes "a controlled trial of plasmapheresis", appears most likely to address the issue at hand, the effectiveness of plasmapheresis in improving clinically important outcomes. The relevant article is a randomized trial in which 46 patients received a standard therapeutic regimen of prednisone and cyclophosphamide, and 40 patients received standard therapy plus plasmapheresis [3] . Despite the fact that antibody levels decreased in those undergoing plasmapheresis, there was a trend toward a greater proportion of the plasmapheresis-treated patients dying (20% versus 13%) or developing renal failure (25% versus 17%). This seems to settle the issue of whether to offer your patient plasmapheresis. You wonder, however, whether the study could have led to an inaccurate or biased outcome. The remainder of this