How to estimate treatment effects from reports of clinical trials. I: Continuous outcomes

Properly conducted randomised trials can aid clinical decision-making by providing unbiased estimates of the average size of treatment effects. This paper, the first of two, discusses how readers of clinical trials can extract simple estimates of treatment effect size from trial reports when trial outcomes are measured on a continuous scale. When making decisions about therapy for individual patients, these estimates can be modified on the basis of patient characteristics. Modified estimates of treatment effect size can be used to determine if the effect of treatment is likely to be large enough to be "clinically worthwhile". This approach optimises clinical decision-making by combining unbiased estimates of the size of treatment effect from clinical trials with clinical intuition and patient preferences.