Kaptchuk TJ, Stason WB, Davis RD, Legedza ATR, Schnyer RN, Kerr CE*, Stone DA, Nam BY, Kirsch I, Goldman RH.

Sham device vs inert pill: a RCT comparison of two placebo treatments for arm pain due to repetitive use.

Osher Institute, Harvard Medical School, Landmark Building, 401 Park Dr, Boston, MA 02215. ted_kaptchuk@hms.harvard.edu *Presenting author

OBJECTIVE: To investigate whether a sham device (a validated sham acupuncture needle) has an enhanced placebo effect compared to an inert pill in patients with persistent arm pain due to repetitive use.

DESIGN: A single blind randomized controlled trial (RCT) created from the two-week placebo run-in periods for two nested RCTs comparing acupuncture and amitriptyline with their respective placebo controls. Comparison of participants who remained on placebo is continued beyond the run-in period to the end of the study.

SETTING: Academic medical center in the US.

PARTICIPANTS: 270 adults with arm pain due to repetitive use persisting for at least three months despite treatment and who scored 3 or higher on a 10-point pain scale.

INTERVENTIONS: Sham acupuncture device twice weekly for six weeks or placebo pill once daily for eight weeks.

OUTCOME MEASURES: Arm pain measured on a 10-point pain scale. Secondary outcomes were arm symptoms measured by the Levine Symptom Severity Scale, arm function measured by Pransky's Upper Extremity Function Scale, and grip strength.

RESULTS: Pain decreased during the two-week placebo run-in period in both the sham device and placebo pill groups, but changes were not different between the groups (-0.14; 95% CI -0.52 to +0.25, p = 0.49). Changes in arm symptoms severity scores and grip strength were similar between groups, but arm function improved more in the placebo pill group (+2.0; 95% CI +0.06 to +3.92, p = 0.04). Longitudinal regression analyses that followed participants throughout the treatment period showed significantly greater downward slopes per week on the 10-point arm pain scale in the sham device group than in the placebo pill group (- 0.33; 95% CI -0.40 to -0.26 versus -0.15; 95% CI -0.21 to -0.09, p = 0.0001) and on the arm symptom severity scale (-0.07; 95% CI -0.09 to -0.05 verses -0.05; 95% CI -0.06 to -0.03, p = 0.02). Differences were not statistically significant, however, on the arm function scale or for grip strength. Reported adverse effects were of totally different types in the sham acupuncture and placebo pill groups.

CONCLUSIONS: The sham device had greater effects than the placebo pill on self-reported arm pain and arm symptom severity over the entire course of treatment, but not during a two-week placebo run-in. Placebo effects are malleable and depend on the behaviors embedded in medical rituals.

 

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