Trials	Hypothesis tested	Population	Modification of the power of the placebo effect	Treatments	Endpoints
Kam‐Hansen et al (2014) 25	Additive model and interactive model	66 chronic migraine patients	Oral information on the treatment administered	Treatment group (razatriptan) and placebo in minimized, neutral or maximized situation	Relief 2 h after onset of migraine symptoms and number of subjects without pain at 2.5 h
Walach et al (2009) 26	Placebo effect depending on a nonlocal correlation with response to treatment	75 healthy volunteers	Oral information on the treatment administered	Treatment group (caffeine) and placebo in maximized or neutral situation	Objective parameters (SAT, DAT, CF, reaction time) and subjective parameters (calm, mood and alertness)
Hammami et al (2016) 27	Interactive model	480 healthy volunteers	Oral information on the treatment administered	Treatment group (hydroxyzine) and placebo in minimized, neutral or maximized situation	Drowsiness and dry mouth, self‐assessed by the participants during the 7 h following treatment
De Craen et al (2001) 16	Interactive model	112 chronic pain patients	Written information on the treatment administered	Treatment group (tramadol) and placebo in maximized or neutral situation	Primary endpoint: pain reduction on self‐assessing VAS
Hammami et al (2010) 28	Interactive model and pharmacokinetic modification of the placebo effect	180 healthy volunteers	Oral information on the treatment administered	Treatment group (caffeine) and placebo in maximized or minimized situation	Subjective self‐assessed (energy, fatigue, nausea) and objective parameters (systolic blood pressure)
Bjorkedal et al (2011) 29	Interactive model: variation of treatment activity according to adverse effects	20 healthy volunteers	Oral information that a powerful painkiller was administered (in fact, caffeine)	Treatment (caffeine) and placebo groups in maximized or minimized situations	Wakefulness, stress, pain, expectations and laser‐evoked potentials
Mitchell et al (1996) 30	Interactive model	40 healthy volunteers	Oral information on the treatment administered	Treatment group (d‐amphetamine) and placebo in maximized or minimized situation	Different scales of drug response (ARCI, DEQ, POMS)
Alasken et al (2015) 10	Interactive model: inversion of treatment effects by means of information	142 healthy volunteers	Oral information that analgesic or hyperalgesic cream was going to be administered	Treatment group (EMLA cream) and placebo in minimized or maximized situation	Endpoints evaluated after painful stimulus, including pain, stress and blood pressure
Lund et al (2014) 31	Interactive model, being of more import with powerful placebo effect	46 healthy volunteers	Oral information on the treatment administered	Treatment group (lidocaine) and placebo in minimized or maximized situation	Self‐assessed pain duration and its maximal intensity after painful stimulus by IM injection
Butcher et al (2012) 32	Variation of the placebo effect according to gender	20 healthy volunteers	Oral information on the treatment administered	Treatment group (ibuprofen) and placebo in minimized or maximized situation	Self‐assessed pain after painful electric stimulus
Berna et al (2017) 33	Interactive model: activity variation according to adverse effects	100 healthy volunteers	Oral information that an analgesic yielding a dry mouth would be administered (in fact, it was atropine)	Treatment group (diclofenac) and placebo in minimized or maximized situation	Analgesia evaluated by VAS after painful thermal stimulus
Flaten et al (1999) 34	Interactive model	66 healthy volunteers	Oral information on the treatment administered	Treatment group (carisoprodol) and placebo in minimized, neutral or maximized situation	Eyeblink reflex, skin conductance, self‐assessment of level of stress and drowsiness
Flaten et al (2004) 35	Interactive model	94 healthy volunteers	Oral information on the treatment administered	Treatment group (carisoprodol), caffeine and placebo in minimized, neutral or maximized situation	Eyeblink reflex, self‐assessment of level of wakefulness and calm, skin conductance, cardiac rhythm, arterial tension
Brandwhaite et al (1981) 36	Interactive model	835 women presenting with chronic headaches	Oral information provided on the “brand” of treatment administered	Treatment group (aspirin) and placebo in minimized or maximized situation	Pain self‐assessment 30 min and 1 h after headaches
Atlas et al (2012) 37	Interactive model	14 healthy volunteers	Oral information on the treatment administered	Treatment group (remifentanil) and placebo in minimized or maximized situation	Self‐assessed pain after painful thermal stimulus
Kirsch et al (1993) 38	Interactive model	100 healthy volunteers	Oral information on the treatment administered	Treatment group (caffeine) and placebo in minimized or maximized situation	Level of alertness and stress, systolic and diastolic tension and cardiac rhythm at 15, 30 and then 45 min after ingestion
Penick et al (1965) 39	Interactive model	14 healthy volunteers	Oral information on the treatment administered	Treatment group (epinephrine) and placebo in minimized or maximized situation Endpoints: l	Level of perceived stress, glucose and free fatty acid concentration and cardiac rhythm
Schenk et al (2013) 40	Interactive model	34 healthy volunteers	Oral information provided on the treatment administered	Treatment group (lidocaine) and placebo in minimized or maximized situation	Self‐assessment of pain on VAS after painful thermal stimulus
Faasse et al (2016) 41	Additive model	87 patients presenting with chronic headaches	Oral information provided on the treatment brand administered	Treatment group (ibuprofen) and placebo in minimized or maximized situation	Home self‐assessment of pain following headache episodes and reported adverse effects
Wise et al (2009) 42	Interactive model	601 poorly controlled asthmatics	Oral information provided on the treatment administered, its brand and its colour	Treatment group (montelukast) and placebo in neutral or maximized situation	Improvement at 4 wk of peak expiratory flow, improvement of pulmonary functions evaluated by spirometry and asthma control evaluated by four self‐assessment scales
Kemeny et al (2007) 43	Variation of the placebo effect and its determinants	55 poorly controlled asthmatics	Oral information provided on the treatment administered	Treatment group (salmeterol) and placebo in maximized or neutral situation	Concentration of methacholine needed to induce a 20% FEV1 decrease
Rose et al (2001) 44	Interactive model	53 healthy volunteers	Oral and written information on the treatment administered	Treatment group (melatonin) and placebo in minimized or maximized situation	Subjective sleep evaluated by a 12‐question assessment scale
Ross et al (1962) 19	Interactive model	80 healthy volunteers	Hidden administration of treatments to minimize their effect	Treatment group (d‐amphetamine) and placebo in the same neutral or minimized situations	Mood swings (Clyde mood scale) and level of performance (tapping task and H‐bar test)
Levine et al (1984) 45	Placebo effect independent of the means of administration	96 patients having undergone dental extraction	Hidden administration of treatments, manually or by a machine	Treatment group (naloxone) and placebo in minimized, neutral or maximized situation	Self‐assessment of pain 50 min after treatment administration
Uhlenhuth et al (1959) 7	Interactive model	52 psychiatric patients suffering from anxieties	Neutral or positive attitude concerning the treatments administered	Treatment group (meprobamate or phenobarbital) and placebo in neutral or maximized situation	Improvement perceived by patients, assessment by a psychiatrist and a scale grouping together 45 symptoms
Uhlenhuth et al (1966) 46	Interactive model	138 patients referred to psychiatric clinic	Neutral or positive attitude concerning the treatments administered	Treatment group (meprobamate) in neutral or maximized situations and placebo in the same situations	Modifications on different scales
Mathews et al (1983) 47	Interactive model	48 couples presenting with sexual disorders	Frequency of administration and number of therapists	Treatment group (testosterone) and placebo with weekly or monthly administration and at least one therapist	Improvement of symptoms evaluated by an outside investigator and the couples themselves
Van Der Molen et al (1988) 48	Hyperventilation in the event of lactate injection or stressful information	13 healthy volunteers	Oral information provided on the treatment administered	Treatment group (lactate) and placebo in minimized (relaxing information) and maximized (stressful information) situations	Anxiety, pCO2 and respiratory rate
Lyerly et al (1964) 49	Interactive model	90 veterans and 90 young employees	Oral information provided on the treatment administered	Treatment group (amphetamine and chloral hydrate) versus placebo in minimized, neutral or maximized situation	Mood swings (Clyde mood scale) and level of performance (tapping task and H‐bar test).
Bergmann et al (1994) 9	Interactive model	49 cancer patients	Oral information provided or not on the study procedure	Treatment group (500 mg of naproxen) and placebo in neutral or maximized situation	Self‐assessment of pain on VAS up to 3 h after administration

Detailed study characteristics. A minimized situation corresponds to less placebo effect power compared to a neutral or maximized situation.

Abbreviations: ARCI, addiction research center inventory; CF, cognitive function; DAT, direct antiglobulin test; DEQ, drug effect questionnaire; EMLA, eutectic mixture of local anaesthetics; FEV1, forced expiratory volume in 1 second; IM, intramuscular; pCO₂, partial pressure of carbon dioxide; POMS, profile of mood states; SAT, spontaneous awakening trials; VAS, visual analogue scale.