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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 2.1

You are the director of a university pain clinic, and are reviewing the effectiveness of epidural steroid injection for chronic low back pain. Your staff has carried out 100 such injections over the past two years in patients who fail to respond to a regimen of physical therapy and nonsteroidal anti-inflammatory drugs. Pain for the previous 24 hours is assessed by the patient on a 0 to 100 numerical scale just before the injection and two weeks later.

The data show that 60% of the patients have their pain reduced by half or more at two weeks, compared to baseline.

A reasonable conclusion from these data is:

Selection AThe data strongly suggest efficacy, as the proportion of patients improving is well above the usual 30% placebo response.
Selection BThe improvement may be due to "regression to the mean," the tendency for patients with chronic symptomatic disorders to enter studies at times of exacerbation and to then improve spontaneously.
Selection COne really cannot tell how much of the improvement is due specifically to the steroid without including a group that gets a placebo injection.