Abstract
Objective: Since placebo and nocebo-responses during acupuncture therapy are rarely studied in clinical contexts, the objective was to investigate placebo and nocebo-responses in a clinical context through comparing positive and negative side-effects between genuine and sham acupuncture, and to identify factors modifying placebo and nocebo-responses. Methods: Patients reported positive side-effects (non-intended positive effects) or negative side-effects (non-intended negative effects) of genuine (penetrating; n = 109) or sham (telescopic non-penetrating; n = 106) acupuncture during 5 weeks of chemoradiation for cancer. Results: The genuine and the sham acupuncture group reported rather similar frequencies of positive (P-values .223-.800) or negative (P-values .072-1.0) side-effects: relaxation 59%/57% of the patients, improved mood 46%/38%, improved sleep 38%/38%, pain-reduction 36%/28%, tiredness 42%/42%, feeling cold 37%/31%, sweating 23%/21%, and dizziness 20%/12%. Positive side-effects occurred in 79% of patients who highly believed acupuncture to be effective, compared to in 0% of patients who did not believe. Other factors associated with placebo-response were female sex (P = .042), anxious mood (P = .007), depressed mood (P = .018), and blinding-success (P = .033). Factors associated with nocebo response were female sex (P = .049), younger age (P = .010), and needle-induced pain (P = .014). Sham-treated patients experiencing positive side-effects experienced better quality of life at the end of the treatment period (mean, m 64 on a scale 0-100 millimetres, Standard Deviation, SD, ±26.1 mm) than those who did not (m 48 ± 25.5 mm), P = .048 (adjusted for other characteristics). Conclusions: Clinically significant levels of placebo and nocebo effects commonly occurred during acupuncture therapy in integrative cancer care and this paper identified factors modifying these responses. This implicates that acupuncture-delivering therapists striving to maximize placebo-responses and minimize nocebo-responses may considering strengthen the patient's treatment expectations, and offer a pleasant, pain-free, acupuncture treatment.