1 INTRODUCTION
Anxiety is an emotional response to stimuli that humans perceive as threatening.However, there is no previous meta-analysis about nursing interventions (interventions managed or applied exclusively by nurses) for preoperative anxiety as it happens with other interventions.1.1 Background
Preoperative anxiety can produce physio-pathological effects such as tachycardia, arrhythmias or hypertension, causing a greater surgical risk, greater anaesthetic requirements, increased postoperative complications such as an increase in postoperative pain levels, nausea and vomiting, as well as a delay in hospitalization or postoperative stay (Celik & Edipoglu, 2018; Jaruzel & Gregoski, 2017).Many researchers have investigated different interventions for reducing preoperative anxiety, being some effects sizes estimated with meta-analysis, using intervention with guided imagery, music therapy, art therapy, clowns, or therapeutic play, among others (Alvarez-Garcia & Yaban, 2020; Gomez-Urquiza et al., 2016; He et al., 2015; Zhang et al., 2017) with positive results.There are currently two classifications of anxiety disorders, presented by the American Psychiatric Association in its diagnostic and statistical manual of mental disorders (DSM-5), and in the medical classification (ICD-10) (Ruiloba et al., 2015).Anxiety implies responses that not only affect the psychological and emotional sphere, but also have physiological and functional consequences (Stamenkovic et al., 2018).However, when the organism reacts in a non-adaptive way and this reaction is exaggerated, anxiety is considered pathological, that is, as a mental disorder (Ruiloba et al., 2015).Anxiety as a trait implies a habitual and prolonged tendency over time to react anxiously, being related to the personality of the subject, while anxiety as a state refers to the reaction in the present moment (Ruiloba et al., 2015).In addition, the volume of registered surgical interventions has increased in recent years.