The interpretation of negative randomized clinical trials

Randomized clinical trials without statistically significant differences be tween treatment groups may provide useful information for clinicians. Howev er, negative trials must be interpreted cautiously, since the absence of ev idence of treatment effect is not the same as evidence of absence of treatm ent effect. Before the reader of a negative article can conclude that one i ntervention was not better than the other, the potential causes of a negati ve study should be explored. The objective of this manuscript is to critica lly describe some of the most common methodological problems that can expla in the lack of difference between studied groups in randomized clinical tri als.