Table 1.

Summary of included studies' characteristics.

Study	Design		Sample		Treatment		Expectancy	Outcome
		N	% Female	Previous use	Acupuncturea	Placebo
Berk et al. (1977) [48]	2 × 2 between-subjects design with acupuncture (real versus placebo) and milieu (positive versus negative) as factors on shoulder pain.	42	29%	No	Acupuncture at LI11, LI4, LI15, GB39, SI9, S10, and M-UE-48 three times over 3 weeks. Needles were manually manipulated, but retention time was not reported.	Noninsertion at the study acupuncture points involving gently pressing the tip of the needle against the skin.	Manipulated—participants randomised to receive acupuncture with positive milieu suggesting that acupuncture is an effective therapy or a negative milieu suggesting that acupuncture is an ineffective treatment.	Objective—shoulder mobility. Self report—pain.
Knox et al. (1979) [52]	3 × 3 between-subjects design with acupuncture (real, placebo, or none) versus expectancy (positive, negative, or variable) for experimentally-induced pain (cold pressor).	72	50%	No	Electroacupuncture at LI4 and TH5 once for 20 min unilaterally on the arm to be placed in the cold pressor. Sensation not reported.	As per acupuncture, but stimulated study points unilaterally on the arm not placed in the cold pressor. A no treatment control group lay down for 20 min and did not receive either treatment.	Manipulated—participants led to expect pain relief, no pain relief, or variable effects from acupuncture or from lying down for 20 min.	Self report—pain at 30 sec.
Norton et al. (1984) [53]	RCT of acupuncture versus placebo for experimentally-induced pain (cold pressor).	24	50%	No	Electroacupuncture at LI5, LI11, SI5, and SI8 once for 15 min unilaterally on the arm to be placed in the cold pressor.	Insertion 2 cm distal to study acupuncture points.	Assessed—expectancy questionnaire comparing treatments (e.g., surgery, morphine, aspirin, and acupuncture) for relieving pain and then categorised participants in to high and low expectancy on the basis of this questionnaire.	Self Report—pain.
Ballegaard et al. (1995) [55]	RCT of acupuncture versus placebo for angina pectoris.	32	22%	Not for heart disease.	Electroacupuncture LI4 for 20 mim. Ten treatments over 3 weeks. De qi and visible muscle twitch achieved.	Superficial (shallow) insertion outside Chinese meridians and not on trigger points with no stimulation.	Assessed—rating of expectancy concerning anti-anginal effects of acupuncture as “very high expectations”, “somewhat high”, “neutral”, “slightly negative”, “moderately negative expectations”, or “don't know”. These scores were dichotomised into either maximal expectation consisting of those who responded “very high expectations” and into submaximal expectations for all others responses.	Objective—exercise tolerance; rate pressure product; nitroglycerin consumption; angina attack rate. Self report—daily wellbeing.
Linde et al. (2007) [49]	Pooled analysis of 4 RCTs of acupuncture versus placebo for migraine, headaches, back pain, and osteoarthritis of the knee.	864	75%	Not stated.	Acupuncture protocol specific to RCT, but all were treated once per week for 12 weeks and each session lasted 30 min.	Superficial needling at nonacupuncture points (relevant to each RCT) also once per week for 12 weeks and each session lasting 30 min.	Assessed—(a) “How effective do you consider acupuncture in general?” and could respond “very effective”, “effective”, “slightly effective”, “not effective”, or “don't know”. (b) “What do you personally expect from the acupuncture you will receive?” and could respond “cure”, “clear improvement”, “slight improvement”, “no improvement”, “don't know”. Dichotomised into high expectancy (top two responses) versus low expectancy (all other responses).	Self report—50% improvement in primary outcome related to trial condition; pain disability index.
Bertisch et al. (2009) [50]	Comparison of placebo acupuncture versus placebo pill within a larger RCT for distal upper arm pain due to RSI.	60	53%	Not for arm pain and not within last year.	N/A	Streitberger placebo needles twice per week for 2 weeks at between 5–10 sites and unilaterally or bilaterally depending on the patients pain.	Assessed—“rate how intense you think the pain or discomfort will be 2 weeks from now if you are assigned to acupuncture” 5-point scale.	Self report—pain.
Kong et al. (2009) [35, 54]	2 × 2 between-subjects design with acupuncture (real versus placebo) and expectancy (high versus low) as factors for experimentally-induced pain (heat stimulation).	48	50%	No	Electroacupuncture at LI3 and LI4 once for 25 min. Di qi achieved.	Streiberger placebo needles placed on the surface of the skin at the study acupuncture points and connected to a deactivated electroacupuncture device.	Manipulated—participants given stimulation of pain with intensity surreptitiously manipulated so as to provide experience of acupuncture treatment decreasing pain (high expectancy) or with intensity identical to baseline so as to provide experience of acupuncture failing to decrease pain (low expectancy).	Self report—pain.
Sherman et al. (2010) [51]	RCT of individualised acupuncture, standardised acupuncture, placebo acupuncture, and standard care for chronic back pain.	477	61%	No	(a) Individualised acupuncture with points and sensation determined based on patients' individual diagnosis. Ten treatments in 7 weeks. (b) Standardised acupuncture at B23, B40, K3 bilaterally and Du3, main trigger point unilaterally for 20 min with manual stimulation to elicit “de qi”.	(a) Placebo acupuncture involving sham insertion using a toothpick in a needle guide tube as per the standardised acupuncture, including manipulation via twisting the tooth pick. (b) Standard care was the usual care participants received from their physicians, if any.	Assessed—participants rated how helpful they believed acupuncture would be for their back pain on 11-point scale. Responses trichotomised into low (0–5), medium (6 and 7), and high (8–10).	Self report—disability; symptom bothersomeness.
Suarez-Almazor et al. (2010) [33]	2 × 2 trial with communication style (positive or negative) and acupuncture (real or placebo) as factors and an additional waitlist control group for osteoarthritis of the knee.	527	61%	No	Electro-acupuncture at GB34, SP6, SP9, Ear-Knee, Ex-LE2, Ex-LE4, Ex-LE5, and 1-2 trigger points. Needle retention was 20 min and treatment lasted 6 weeks although the number of sessions per week was not reported.	Shallow insertion at acupoints not relevant to the knee.	Manipulated—participants randomised to an acupuncturist who communicated positive messages about acupuncture, for example, “I think this will work for you”, or to neutral communication such as, “It may or may not work for you”.	Self report—pain, satisfaction; physical and mental satisfaction. Objective—range of motion; timed up and go test.

^aAll bilateral acupuncture points stimulated bilaterally unless specified otherwise.