Placebo response in neuropathic pain after spinal cord injury: a meta-analysis of individual participant data

Journal of Pain Research, 2018 · DOI: http://dx.doi.org/10.2147/JPR.S155979 · Published: January 1, 2018

Spinal Cord Injury Pain Management Research Methodology & Design

Simple Explanation

The study aims to understand factors that lead to high placebo responses in clinical trials, as this can help in identifying the true effectiveness of treatments. The research involved analyzing data from multiple studies focusing on individuals with spinal cord injuries (SCI) who experience neuropathic pain. The study found that being male and having higher pain levels at the start of a trial were linked to a stronger placebo response.

Study Duration

>4 weeks

Participants

276 patients with SCI

Evidence Level

Not specified

Key Findings

1
Larger placebo responses were observed in male subjects with SCI-related neuropathic pain.
2
Higher baseline pain intensity was associated with increased placebo responses.
3
Injury characteristics such as severity, level, and time since injury did not significantly affect placebo responses.

Research Summary

This study investigates factors influencing placebo responses in SCI patients with neuropathic pain using individual patient data from six RCTs. The analysis revealed that sex and baseline pain intensity are significantly associated with placebo responses, with males and those reporting higher initial pain experiencing larger placebo effects. The study concludes that low placebo responses are typical in SCI neuropathic pain trials, and injury characteristics do not predict changes in pain ratings.

Practical Implications

Clinical Trial Design

Consider sex and baseline pain intensity when designing clinical trials for SCI neuropathic pain.

Patient Expectations

Address patient expectations in both placebo and active treatment groups to better understand placebo responses.

Further Research

Explore the impact of damage in the CNS on placebo analgesia in individuals with SCI.

Study Limitations

1
The limited number of trials restricts the results of the IPD meta-analysis.
2
Important variables, such as a measure of expectation, were not examined.
3
The clinical measure of damage in the spinal cord may be insufficient to characterize the extent of pathology in spinal pathways involved in placebo analgesia.

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