What Is Clinically Meaningful: Outcome Measures in Pain Clinical Trials

OBJECTIVE: The goal of this analysis is a better understanding of the issues involved in establishing the amount of change in pain that must be reported by subjects, participating in clinical trials and using standard pain scales, to indicate a clinically important difference. DESIGN: A review of the literature and a discussion of relevant concepts are presented. The focus is on outcome measures of pain commonly used in the studies described, including pain intensity, pain relief, global assessment of the medication effect, and requirement for an extra dose of rescue medication to treat a pain episode. The standard analysis statistics used to summarize the data are the central tendency of the groups being compared (i.e., mean, median, or mode), and the proportion of subjects that achieve one or more specific levels of benefit. RESULTS: The analysis of the proportion of responders in the groups being compared allows for a more easily understandable clinical importance of the results. CONCLUSIONS: An analysis of the proportion of responders is a clinically relevant analysis for many pain clinical trials and should be presented for one or more levels of response as appropriate. This will allow the readers to more easily interpret the results and apply them to clinical practice.