What is clinically meaningful: Outcome measures in pain clinical trials

Objective: The goal of this analysis is a better understanding of the issue s involved in establishing the amount of change in pain that must be report ed by subjects, participating in clinical trials and using standard pain sc ales, to indicate a clinically important difference. Design: A review of the literature and a discussion of relevant concepts ar e 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 medi cation to treat a pain episode. The standard analysis statistics used to su mmarize the data an the central tendency of the groups being compared (i.e. , mean, median, or mode), and the proportion of subjects that achieve one o r more specific levels of benefit. Results: The analysis of the proportion of responders in the groups being c ompared allows for a more easily understandable clinical importance of the results. Conclusions: An analysis of the proportion of responders is a clinically re levant analysis for many pain clinical trials and should be presented for o ne or more levels of response as appropriate. This will allow the readers t o more easily interpret the results and apply them to clinical practice.