Psychologic Factors Do Not Affect Placebo Responses After Upper Extremity Injections: A Randomized Trial

Area of Science:

• Psychology
• Pain Management
• Clinical Trials

Background:

• Psychological factors' influence on placebo effects yields conflicting research findings.
• While some studies link pessimism to nocebo effects, others suggest depression, anxiety, or neuroticism enhance placebo response.
• Understanding these psychological mediators is vital for optimizing treatment benefits and clinical outcomes.

Purpose of the Study:

• To investigate psychological factors associated with reduced pain and disability after placebo injections for upper extremity conditions.
• To determine if psychological factors predict achieving minimum clinically important differences (MCID) in pain and disability.

Main Methods:

• Secondary analysis of data from two prospective, double-blind, randomized controlled trials involving patients with painful upper extremity conditions.
• Included 43 patients receiving lidocaine placebo injections, assessing Disabilities of the Arm, Shoulder and Hand (DASH) and Visual Analog Scale (VAS) for pain.
• Analyzed psychological factors including depression, coping strategies, and personality traits using multivariable regression models.

Main Results:

• No psychological factors were significantly associated with changes in DASH scores or pain intensity (VAS) after placebo injection.
• No psychological factors independently predicted achieving MCID in either disability or pain intensity.
• The study found no significant psychological predictors for placebo response in this cohort.

Conclusions:

• Patient psychological factors were not significant mediators of the placebo effect in this study.
• Clinician factors, such as warmth and competence, may be more influential in placebo response.
• These findings suggest focusing on clinician-patient interactions to enhance treatment outcomes.