The choice effect on open label placebo for chronic pain

INTERVENTION: Participants with chronic pain will be randomized to one of three groups: Choice, No Choice and Natural History. Participants randomized to Choice and No Choice groups will receive an open‐label placebo (OLP) treatment and will be asked to use their treatment twice every day for two weeks. Those randomized to Natural History will not receive any treatment. The Choice group will be given the opportunity to choose their OLP treatment between oral pills and nasal spray before the two‐week treatment period and decide when to take each of two doses every day. The No Choice group will be assigned a OLP treatment by the researcher and must use the treatment once in the morning and once in the evening every day for two weeks. Treatment adherence will be assessed by self‐report after the two‐week treatment period. CONDITION: Alternative and Complementary Medicine ‐ Other alternative and complementary medicine Anaesthesiology ‐ Pain management Chronic Pain; ; Chronic Pain PRIMARY OUTCOME: Pain intensity assessed by Brief Pain inventory[Baseline, 2 weeks post‐initiating treatment] SECONDARY OUTCOME: Anxiety, measured using the Depression Anxiety Stress Scales ‐ 21 (DASS‐21)[Baseline, 2 weeks post‐initiating treatment] Depression, measured using the Depression Anxiety Stress Scales ‐ 21 (DASS‐21)[Baseline, 2 weeks post‐initiating treatment] Evaluation of the effectiveness of the choice manipulation, assessed by asking participants in the OLP arms "How much choice do you feel you had over your treatment?” (1 = no choice at all; 10 =complete choice).[2 weeks post‐initiating treatment] Fear of movement or (re)injury, assessed using Tampa Scale of Kinesiophobia[Baseline, 2 weeks post‐initiating treatment] Pain interference assessed by Brief pain inventory[Baseline, 2 weeks post‐initiating treatment] Perceived disability related to chronic pain, assessed using a modified version of Roland‐Morris Disability Questionnaire where “back pain” will be replaced with “pain”[Baseline, 2 weeks post‐initiating treatment] Perceived effectiveness, convenience, side effects and overall satisfaction with the treatment will be measured using the Treatment Satisfaction Questionnaire for Medication – II (TSQM‐II). The scores for each subscale will be summed to calculate a composite score ranging from 0 to 100, where a higher score indicating greater satisfaction with the treatment.[2 weeks post‐initiating treatment] Stress, measured using the Depression Anxiety Stress Scales ‐ 21 (DASS‐21)[Baseline, 2 weeks post‐initiating treatment] Treatment adherence, assessed by asking participants “Over the past 14 days, on how many days did you take two placebo pills/use nasal spray twice?”[2 weeks post‐initiating treatment] INCLUSION CRITERIA: • Age 18 and above • Self‐reported persistent pain on more days than not for at least three months • Self‐reported current pain intensity of moderate or greater severity (evidenced by a score of > 3 (/10) on a pain intensity numeric rating scale, PI‐NRS). • Willingness to provide written informed consent • Willingness to participate and comply with the study protocol • Fluent in English • Competent to give consent