Selective clinical trial reporting: betraying trial participants, harming patients

Reporting biases in published trials were first identified in 1986.1 Published randomized studies of combination chemotherapy compared with treatment with an alkylating agent as first line treatment for ovarian cancer showed a significant survival advantage for combination chemotherapy. Unpublished cancer trial registry data from the same studies, however, showed no such advantage.2 Similarly, in the treatment of multiple myeloma, registry data suggested a smaller survival advantage for combination chemotherapy (over prednisone and an alkylating agent) than the results of published studies. The author who reported the discrepancy concluded that his findings “demonstrate the value and importance of an international registry of all clinical trials.”1 Subsequent evidence for biased and selective reporting included prompt or delayed publication depending on whether trial results were positive or negative3 and more favorable results and conclusions in published studies funded by industry than in those funded independently.4

The linked paper by Chang and colleagues (doi:10.1136/bmj.h2613) shows …