“…If a study, for instance, reported standard care as comparator, but did not specify what exactly standard care Interaction with clowns during a minimum of 3 days (50) Parents ( 49 Note. CAPS = Children Anxiety and Pain Scale (Kuttner & LePage, 1989); RCTs = randomized controlled trials; CSWQ = Child Surgery Worries Questionnaire (Quiles et al, 2000); FLACC = Face, Legs, Activity, Cry, Consolability scale (Merkel et al, 1997); FPS-r = Faces Pain Scale-Revised (Hicks et al, 2001); mYPAS = modified Yale Preoperative anxiety scale (Kain et al, 1995); NRS = Numerical Rating Scale (von Baeyer et al, 2009); PSS-I = Posttraumatic Stress Disorder Symptom Scale (Foa et al, 1993); STAI = State-Trait Anxiety Inventory (Speilberger et al, 1983); VAS = Visual Analogue Scale; WB = Wong Baker Faces Pain Scale (Wong & Baker, 1988); OR = operation room; AAI = animal-assisted intervention; iv = intravenous; MRI = magnetic resonance imaging. a, b These studies were split into two sub-studies each because different instruments were used for different age groups; * Quasi-randomized trial; ** mean age was calculated using the provided formula of Wan et al (2014).…”