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Trial Design: Pain Sections
Author Bio
Introduction
Currently selected section: Placebo Effects
Single Dose Trials
Repeated Dose Trials
Explanatory Versus Pragmatic
Dose-Response
Parallel Group Versus Crossover
Conclusion
 

 

Chapter 1: Clinical Trials of Pain Treatment: Placebo Effects and Their Implications for Pain Studies
 
       

PROBLEM 2.2
 "ACTIVE" PLACEBO

You are asked to review the results of a study with an experimental analgesic drug, Drug G, in chronic arthritic pain. Fifty patients each have taken 3 weeks of Drug G or a placebo.

Result :

Pain Intensity:

Figure 2.3 shows that both treatment groups had comparable pain at baseline, but Drug G reduced pain significantly more than did placebo.

Click on image to enlarge
Figure 2.3 shows that both treatment groups had comparable pain at baseline, but Drug G reduced pain significantly more than did placebo. Drug G was superior to placebo at p< .05.


Side Effects:

All patients on Drug G and 2/50 on placebo noted moderate to severe sedation during initial drug titration.

What is your interpretation of this result and your suggestion for further studies?

Selection AAlthough there is a statistically significant result, a reduction of pain by an average of 20% is not clinically significant.  
Selection BThe magnitude of pain reduction is potentially useful, but the production of sedation by Drug G and not placebo unblinded the study. Drug G may be entirely without specific analgesic effects; the sedative side effects having biased patients towards reporting pain relief.
Selection CThe study should be replicated with the inclusion of a questionnaire to examine whether patients and research staff can guess what the treatment assignment is.
Selection DThe study should be replicated with the two treatment groups being Drug G or an active placebo, a low dose of a benzodiazepine to mimic the sedative side effects of Drug G.