Psychodrama: implementation, study design and effectiveness: a systematic review

Abstract

Background

Psychodrama is a psychotherapy model in which action-focused techniques are used to improve the quality of life of patients. A systematic review of the psychodrama interventions published between 2018 and 2022 is carried out in order to recognize the implementation of psychodrama (population, objectives, theoretical model, modality, intensity, periodicity, duration of sessions, psychodramatic techniques, and sistematization); to analyze the methodological design for evaluating the impact of psychodrama interventions (study design and RCT); and to consider the results of the effectiveness of psychodrama.

Method

Following the PRISMA declaration protocol, 27 indexed studies have been selected in three databases: PsycINFO, Scopus and Medline. The selected articles met the following inclusion criteria: peer-reviewed papers, written in English, empirical studies, including quantitative, qualitative, or mixed-methods research, corresponding to interventions or treatments based on psychodrama and evaluating the effectiveness of the interventions with 10 participants in pretest-posttest.

Results

In relation to the implementation, psychodrama was applied in a group format with diverse population, especially adolescents and adults, and most of the interventions were implemented weekly (8–13 sessions) and lasted approximately two hours. Generally, these interventions were based on Morenian Psychodrama. Role reversal, doubling and mirror were the techniques most used. No manualized psychodrama treatments were reported. In relation to study design, 62% were evaluated using a quantitative design, 27% with mixed methods, and 11% with a qualitative evaluation. 26% included follow-up assessment. The number of randomized controlled trials (RCTs) is low (11%), mostly detecting quasi-experimental controlled studies (48%) and single group studies (40%). In relation to the effectiveness of psychodrama, positive and significant results were found, for example, in the reduction of post-traumatic stress levels, the empowerment of women in vulnerable situations, improvement in the quality of life and symptoms of patients with schizophrenia, or improvement in antisocial behavior in adolescents. In 40% of the studies, effect sizes were reported, which were typically medium or large. However, the sample size was small for drawing solid conclusions. 22% of the studies did not find significant changes in any dimension. No iatrogenic effects were found.

Conclusions

This data supports the implementation of Morenian Psychodrama in group format across a wide variety of populations, although there are no clear profiles that have a greater impact. However, the methodological design of psychodrama needs improvement: RCTs and quasi-experimental designs, larger sample sizes, follow-up evaluations, and effect size measurement. Additionally, structuring interventions and their manualization in specific populations can help establish evidence-based treatments.

Background

Psychodrama is “a method of psychotherapy in which clients are encouraged to continue and complete their actions through dramatization, role-playing and dramatic self-presentation” [1]. Other authors have defined psychodrama as a psychotherapeutic model due to the emergence of theories [2] that explain the psychological functioning and psychopathology of the individual [3]. Despite the existence of various definitions of psychodrama, it is noteworthy that most of them agree on distinguishing action and dramatization as key elements that differentiate psychodrama from other psychotherapeutic models [4].

Jacob Levy Moreno is considered the founder of psychodrama. Initially, psychodrama emerged as a novel form of group psychotherapy, in which theatrical techniques are used [5]. The two main concepts of Morenian psychodrama are spontaneity and creativity. Spontaneity can be defined as the emotional state to express oneself freely and generate appropriate, self-regulated responses to new situations, catalyzing the process of creativity [6]. According to Moreno [7], creativity is the capacity to generate something that did not exist for the individual, and he considers it essential for individuals to adapt to life changes and face unexpected challenges. According to Morenian Psychodrama [5], creativity and spontaneity are considered the main elements contributing to individuals’ well-being and mental health.

Psychodrama has continued to evolve with new theories, e.g., Rojas-Bermúdez’s role scheme theory [2], and has been integrated with other psychotherapeutic models, including the cognitive-behavioral model [8], the systemic family theory [9], and the psychoanalytic model [10]. Although psychodrama was originally conceived as a group treatment, it is currently regarded as a model that can be applied in individual, couples, and family therapy [11], as well as in contexts beyond the therapeutic setting [12].

Additionally, psychodramatic techniques have been a focal point of research on psychodrama. In a systematic review, Cruz et al. [13] identified core techniques, including soliloquy, double, mirror, role reversal, resistance interpolation, sculpture, social atom, intermediate objects, games, sociometry, and role training.

Effectiveness of psychodrama

Over the past decade, there has been a proliferation of studies evaluating the effectiveness of psychodrama-based interventions with diverse populations. Additionally, following the quality criteria for obtaining evidence-based interventions [14], it is not sufficient to conduct evaluations of specific treatments; rather, experimental or quasi-experimental designs should be promoted, with a particular recommendation for randomized controlled trial (RCT) designs with randomized comparison groups. Several systematic reviews of psychodrama interventions have recently been published, which reflect the current state of psychodrama [15–19].

First, Orkibi and Feniger-Schaal [15] have evaluated the methodological aspects of study designs to assess psychodramatic interventions between 2007 and 2017. The authors highlight that, although research on psychodrama interventions with promising results in almost all areas has increased over the years, some studies need to improve their methodology and transparency to allow for replication of their results. Second, Lim et al. [19] have conducted a scientometric review of articles on psychodrama published over the past 80 years (1940–2021) retrieved from Scopus. The authors identified an increase in the incorporation of technology to facilitate psychodramatic practice, as well as the integration of psychodrama with other psychotherapies. However, they did not provide individualized data extracted from the interventions. Third, López-González et al. [17] have focused on controlled clinical trials to identify evidence of psychodrama outcomes. It includes 14 articles published between 1999 and 2019. The authors extracted data on populations, variables, scales, and main outcomes, highlighting that psychodrama improves symptoms associated with a wide range of psychological problems.

These reviews have shown that psychodrama can be applied in a wide range of settings and populations with promising results. However, among the remaining challenges are improving the methodological quality of studies and increasing the number of RCTs. Additionally, all these reviews include only one article published since 2018. Given the proliferation of psychodrama-based interventions and treatments due to the positive outcomes achieved in the previous decade, this paper aims to present a more up-to-date overview of psychodrama.

For these reasons, a systematic review is proposed with the aim of understanding the current state of psychodrama. The following specific objectives are established: (a) to identify the characteristics of psychodrama implementation (population, intervention objectives, theoretical model, modality, intensity, periodicity, duration of sessions, psychodramatic techniques, and systematization); (b) to analyze the methodological designs used to evaluate the impact of psychodrama interventions (study design, controlled clinical trials, and instruments); and (c) to report the results regarding the effectiveness of psychodrama.

Method

Information sources and search strategy

A systematic search of articles published between 2018 and 2022 in journals indexed in three electronic databases was conducted: PsycINFO, Scopus, and Medline. Consistent with the research question, the search term “psychodrama” and other terms sharing the same root (for example, psychodramatic) were employed. To ensure that the central theme of the article focused on psychodrama, the term had to appear at least in the title or abstract. Specifically, for PsycINFO and Medline, the advanced search command was utilized: TI (psychodrama*) OR AB (psychodrama). For the Scopus database: TITLE-ABS (“psychodrama*”) AND SUBJAREA (psyc).

For data extraction, we followed the PRISMA guidelines and the PICO framework [20]. We extracted the following information: (a) participants (no restrictions were applied regarding age, sex, or other characteristics); (b) intervention (modality, frequency, duration, techniques, theory, and structure) (c) comparisons (single-group with repeated measures, and interaction between intervention and control groups); (d) outcomes (pretest-posttest-follow-up significance, effect size, and qualitative results); and (e) study design (quantitative, qualitative, mixed-methods, RCT, quasi-experimental, or single group designs). Following Aschieri and colleagues [21], we divided the data extraction into three sections: first, quantitative studies; second, qualitative studies; and third, mixed methods.

The selected articles met the following inclusion criteria: (1) peer-reviewed manuscript; (2) written in English; (3) published from January 1, 2018, to October 16, 2022; (4) empirical studies, including quantitative, qualitative, or mixed-methods research; (5) interventions or treatments based on psychodrama; (6) evaluating the effectiveness of the interventions; and (7) with a sample size of 10 or more participants for the pretest-posttest comparison. The date of the last search was November 7, 2022.

Consequently, studies that did not meet these criteria were excluded. For example, studies containing the search term in the title or abstract but not corresponding to psychodrama interventions were discarded. Similarly, articles that were not empirical studies related to psychodrama interventions or did not evaluate their effectiveness were excluded. Additionally, systematic reviews, meta-analyses, editorials, theoretical articles, or instrument validations were discarded. Following the results and criteria of other systematic reviews on psychodrama [17], articles that included single-case studies (n = 1), or articles with a sample size of n < 10 for the pretest-posttest comparison were also excluded.

It should be noted that the article screening process based on title and abstract review was conducted independently by two reviewers. Any discrepancies encountered (2 out of a total of 97 articles reviewed in title and abstract) were resolved through discussion to reach a consensus on the articles to be included in the next phase.

Quality and Bias analysis

The methodology employed in this systematic review aimed to reduce or eliminate various biases. First, to address quality bias, only peer-reviewed articles published in indexed journals were selected. Second, two specific databases (PsycInfo and Medline) and one general database (Scopus) were utilized to minimize indexing bias. Third, full-text versions of all selected articles that met the inclusion criteria during the title and abstract review phase were obtained, thereby eliminating incomplete text bias. Fourth, considering that the selected articles for the systematic review involved more than 60 different authors, efforts were made to minimize authorship bias. Lastly, regarding language bias, only English-language texts were selected, as English is the predominant language for publication in major psychology journals.

Results

Study selection

The selection of potential articles began with an initial search that identified a total of 125 potential papers on psychodrama (47 in PsycINFO, 61 in Scopus, and 17 in Medline). After removing duplicates, 97 articles were selected for the next phase. Two reviewers independently conducted a detailed reading of the title and abstract of each of the 97 selected articles from the previous phase to exclude those that did not meet the eligibility criteria. Specifically, 34 articles were excluded: 25 were not interventions, three had sample sizes that were too small, two exclusively focused on psychoanalysis, four were not related to psychodrama, and the remaining four were discarded for various reasons. Following this screening, 63 articles remained eligible for full-text review; specifically, 11 articles were excluded as they did not correspond to psychodrama interventions, 19 articles had sample sizes that were too small (n < 10), and four studies had their main text not in English. In conclusion, a total of 36 articles were discarded during the full-text review phase, resulting in the final inclusion of 27 articles, which required a new detailed reading of the full text to extract relevant information. Figure 1 summarizes the complete article selection process.

Fig. 1.

Flow diagram of the article retrieval process

Data extraction

The data extraction from the articles are presented in Table 1 (quantitative studies), Table 2 (qualitative studies), and Table 3 (mixed-methods studies). The content extraction is based exclusively on the data included in the published studies. For each study, we extracted the following information: general data—authors, year of publication, country, participants, and sample size—; data related to the implementation of the psychodrama intervention—intervention objectives, theoretical framework, intervention modality (multi-family group, group, family, or individual), intensity, frequency, session duration, psychodramatic techniques used, and the presence of a detailed intervention description (manual, specific data, or general information)—; data related to the evaluation—evaluation design (quantitative, qualitative, mixed methods, pretest, posttest, follow-up, or in-session evaluations)—, presence of RCTs (yes, quasi-experimental or single-group), and instruments; and data related to effectiveness—statistical significance, effect size, and qualitative information when applicable—.

Table 1.

Psychodrama interventions: quantitative study design

GENERAL DATA		IMPLEMENTATION DATA					EVALUATION DATA				EFFECTIVENESS DATA
Author (year) Country	Sample (N intervention group IG and N control group CG)	Intervention objective	Theory	Modality. Intensity. Periodicity. Duration	Techniques	Detailed decription of intervention	Study desing	RCT	Instruments to evaluate pre-posttest or follow-up	p values	Size effect
[22] Albal et al. (2021) Turkey	IG: 13 Psychiatric nurses CG: 13 Psychiatric nurses	Improve emotional awareness and communication skills	Morenian Psychodrama	Group. 16 sessions. 2 sessions per week. 2 h each session	Double, role reversal, role-play, empty chair, social atom, storytelling, symbolic representation, scene construction and mirror	Yes (Specific data)	Quantitative. Pre-posttest evaluation	Yes	Levels of Emotional Awareness Scale (LEAS); Communication Skills Inventory (CSI)	IG*CG Emotional Awareness (p <.05) Communication Skills Total (p >.05)	Emotional awareness (η2 partial = 0.198)
[23] Gotseva-Balgaranova et al. (2020) Bulgaria	IG:15 Children and 16 Parents part of refugee, asylum seeking and immigrant families	Reduce PTSD and depression symptoms	Psychodrama by Alfons Aichinger and Walter Holl	Multiple-family group: parent-child pairs. 9 sessions (4 psychoeducation sessions conducted only with the parents, and 5 stabilization sessions with the parent-child pairs). Intervention can last from 3 to 8 weeks. Duration not specified	Concretisation, symbolic play amongst others	Yes (Specific data)	Quantitative. Pre-posttest evaluation	No (single-group)	Instruments for the adults: Refugee Interview Questionnaire (RIQ); Beck Depression Inventory (BDI); Self-assessment checklist for PTSD symptoms (PCL-5). Instruments for the children: Children Refugee Interview Questionnaire (cRIQ); Trauma Symptoms Checklist for Young Children (TSCYC); Children Stress Checklist (cPC)	Children Pre-post: PTSD total (p >.05) Parents Pre-post: PTSD (p >.05) Depression (p >.05)	Children PTSD total (Cohen’s d = 0.37) Parents PTSD (Cohen’s d = 0.20) Depression (Cohen’s d = 0.31)
[24] Grigorescu et al. (2020) Romania	IG: 11 Nurses previously identified with medium or high levels of burnout CG: 12 Nurses previously identified with medium or high levels of burnout	Reduce the level of burnout	Not specified	Group. 10 sessions. Weekly. 150 min each session	Not specified	Yes (Specific data)	Quantitative. Pre-posttest evaluation	No (quasi-experimental)	Copenhagen Burnout Inventory- the Romanian version. Catell Anxiety Scale. Zung Depression Scale. Cognitive-Emotional Coping Questionaire.	Only intervention group: Total burnout (p >.05); personal burnout (p <.05); work burnout (p <.05); patients burnout (p >.05); General anxiety (p =.05).Depression (p =.05); positive refocusing (p <.05); catastrophizing (p <.05); other coping mechanisms (p >.05). Interaction IG*CG not reported	Not specified
[25] Gulassa et al. (2019) Brazil	IG1: 10 Adult patients with excoriation disorder in psychodrama group IG2: 9 Adult patients with excoriation disorder in support group	Improve levels of excoriation. Explore patterns of interpersonal interactions. Raise awareness of internal emotions processing	Not specified	Group. 20 sessions. Weekly. Duration not specified.	Not specified	General information	Quantitative. Pre-posttest evaluation	No (quasi-experimental)	Skin Picking Scale-Revised (SPS-R); Beck Anxiety Inventory (BAI); Beck Depression Inventory (BDI); Social Adjustment Secale (SAS); Difficulties in Emotion Regulation Scale (DERS)	No significant differences between the psychodrama group and the support therapy group. In psychodrama group: skin excoriation (p <.05).	Not specified
[26] Hamidi and Tabar (2021) Iran	IG: 20Male students with PTSD aged 9–12 years CG: 20 Male students with PTSD aged 9–12 years	Reduce post-traumatic stress symptoms	Not specified	Group. 13 sessions. Weekly. 90 min each session	Not specified	General information	Quantitative. Pre-posttest evaluation	No (quasi-experimental)	PSTD Checklist for DSM5 (PCL-5)	IG*CG: Symptoms of post-traumatic stress (p <.001)	Symptoms of post-traumatic stress (Cohen’s d = 0.51)
[27] Jendričko and Prosen (2020) Croatia	IG: 43 outpatients from a psychiatric clinic with different diagnoses	Improve expectations of psychotherapy treatment and the perception of its outcomes	Morenian Psychodrama	Group. 12 sessions. Weekly. 1 h each session (while maintaining pharmacological treatment)	Not specified	Yes (Specific data)	Quantitative. Pre-posttest evaluation	No (single-group)	Milwaukee Psychotherapy Expectations Questionnaire	Pre-post treatment expectations-process (p <.001) Pre-post treatment expectations-outcome: (p <.05)	Not specified
[28] Kaya (2020) Turkey	IG: 34 Nursing students	Enhance psychological well-being	Morenian Psychodrama	Group.10 sessions. Weekly. 90–120 each session	Mirror, double, role reversal, games amongst others	Yes (Specific data)	Quantitative, Pre-posttest evaluation	NO (single-group)	Subjective Well-Being Scale (SWS)	Pre-post treatment Total subjective well-being (p >.05). Subescales: positive and negative emotions (p =.05); purpose (p <.05). Other subescales (p >.05)	Total subjective well-being (Cohen’s d. = 0.311). Positive and negative emotions (Cohen’s d. = 0.917); purpose (Cohen’s d. = 0.389)
[29] Kaya (2020) Turkey	IG: 15 Nursing students undergraduate students CG: 15 Nursing students undergraduate students	Enhance subjective well-being	Not specified	Group. 23 sessions. Weekly. 180 min each session	Games and role-play	General information	Quantitative. Pretest-follow-up (12 months after pretest)	No (quasi-experimental)	Psychological Well-Being Scale (PWBS)	IG*CG Pre--follow-up Total Psychological Well-Being Scale (p >.05). Only IG: environmental mastery (p <.05). Not significant rest of dimensions	Not specified
[30] Maya et al. (2020) Spain	IG: 109 Adolescents with problematic behaviors CG: 107 Adolescents with problematic behaviors	Reduce problematic behavior and improve family relationships.	Psychodramatic Family Therapy based on Scenes (SB-PFT). Systemic therapy combined with psychodrama	Multiple-family group.10 sessions. Weekly. 2 h each session	Role reversal, mirror, resistance interpolation, amongst others	General information	Quantitative. Pre-posttest evaluation, and follow-up (5 months later)	No (quasi-experimental)	Emotional quotient inventory-youth version (EQ-YV); The inventory of parent and peer attachment (IPPA); Antisocial and criminal behavior questionnaire (A-D)	IG*CG Pre-posttest Emotional intelligence: Intrapersonal intelligence (p >.05) Interpersonal intelligence (p <.01) Adaptability (p >.05) Stress management (p >.05) General mood (p <.01) Parental attachment: Communication (p <.05) Trust (p <.01) Alienation (p >.05) Peer attachment (p >.05) Antisocial behavior (p p >.05) Follow-up: Only IG Emotional intelligence: Adaptability, logarithmic growth (χ2 = 0.211; RMSEA = 0.00) General mood, logarithmic growth (χ2 = 0.075; RMSEA = 0.00) Parental attachment: Communication, exponential growth (χ2 = 2.177; RMSEA = 0.03) Trust, exponential growth (χ2 = 2.575; RMSEA = 0.05) Antisocial behavior, exponential growth (χ2 = 3.422; RMSEA = 0.08)	Pre-posttest Emotional intelligence: Interpersonal intelligence (η2 partial = 0.03) General mood (η2 partial = 0.05) Parental attachment: Communication (η2 partial = 0.03) Trust (η2partial = 0.03)
[31] Mojahed et al. (2021) Iran	IG: 24 Boys with ADHD at a hospital in Iran CG: 24 Boys with ADHD at a hospital in Iran	Reduce aggression, social anxiety and ADHD symptoms	Morenian Psychodrama	Group. 10 sessions. Weekly. 2 h each session	Magic shop, mirror, family imagination, role-playing, role-reversal, storytelling, brainstorming, empty chair and soliloquy, amongst others.	Yes (Specific data)	Quantitative. Pre-posttest evaluation, and follow-up (two months)	Yes	Achenbach’s Child Behavior Checklist (CBCL); Spence Children’s Anxiety Scale (SCAS)	IG*CG Social anxiety pre-post and follow-up (p <.001) Aggression pre-post and follow-up (p <.001) ADHD pre-post and follow-up (p <.001)	Social anxiety (η2 = 0.745) Aggression (η2 = 0.761) ADHD (η2 = 0.633)
[32] Mortan Sevi et al. (2020) Turkey	IG: 31 Inpatients with symptoms of chronic schizophrenia	Improve psychopathological symptoms in chronic schizophrenia	Morenian Psychodrama	Group. 19 sessions. Weekly. 90–120 each session	Not specified	Yes (Specific data)	Quantitative, Pre-posttest evaluation	No (single-group)	Positive and Negative Syndrome scale (PANSS); Calgary depression scale for schizophrenia (CDS); Quality of life scale for schizophrenia (QLS)	Male group pre-post: Psychotic symptoms (p <.01) Depression (p >.05) Quality of life (p <.01) Female group pre-post: Psychotic symptoms (p <.05) Depression (p >.05) Quality of life (p <.01)	Only depression: effect size (statistical not specified) = 0.059
[33] Prosen and Jendričko (2019) Croatia	IG: 24 Outpatients from a psychiatric clinic	Enhance emotion regulation strategies	Morenian Psychodrama	Group. 12 sessions. Weekly.1 h each session	Not specified	General information	Quantitative. Pre-posttest evaluation	No (single-group)	Emotion Regulation Questionaire (ERQ)	Pre-posttest. Reappraisal strategy (p >.05) Suppression strategy (p >.05)	Not specified
[34] Rudokaite and Indriuniene (2019) Lithuania	IG: 61 Secondary school students CG: 163 secondary school students	Reduce school-related fears	Not specified	Group. 4 sessions. One session of 4 h per week for one month	Role reversal, monologue, and sociometry	General information	Quantitative. Pre-posttest evaluation	No (quasi-experimental)	Manifestations of school fears (MA); Strategies for coping with school fears (CO)	Posttest IG*CG: Physiological manifestations (p >.05) Emotional manifestations (p <.001) Cognitive manifestations (p <.01) Coping strategies: Productive working activity (p >.05) Evasion and cheating (p =.05) Relaxation and anticipation (p >.05) Diverting attention and underestimating (p <.05)	Glass Delta physiological manifestations = 0.054. Glass Delta emotional manifestations = 0.584. Glass Delta cognitive manifestations = 0.470 Size effect coping strategies: Glass Delta Productive working activity = 0.546 Glass Delta Evasion and cheating = 0.05 Glass Delta Relaxation and anticipation = 0.181 Glass Delta Diverting attention and underestimating = 0.016
[35] Sepanta et al. (2020) Iran	IG1: (Psychodrama program): 13 fifth-grade female students with a reading disorder. IG2: (Fredrickson’s positive emotion training program): 13 fifth-grade female students with a reading disorder. CG: 12 fifth-grade female students with a reading disorder.	Improve emotional regulation	Morenian Psicodrama	Group. 10 sessions. Periodicity not specified. 45 min each session	Role-playing, mirror, empty chair, scene reconstruction, soliloquy and darkroom technique, amongst others	Yes (Specific data)	Quantitative., Pre-posttest evaluation, and follow-up (three months later)	Yes	Cognitive Emotions Regulation Questionnaire (CERQ)	IG1 (Psychodrama intervention)*GC Emotion regulation (p >.05)	Not specified
[36] Testoni et al. (2021) Italy	IG: 45 Students from a high school where two traumatic deaths occurred CG: 37 Students from a high school where two traumatic deaths occurred.	Carry out a reflection on the issues of finitude, mortality, and spirituality, activating a reflection on what the prospects concerning the after-death might be and on the sense of life in facing death.	Psychodrama combined with art therapy (drama therapy)	Group. 8 sessions. 4 sessions per month. 2 h	Theoretical discussions, role-playing, meditation and other artistic and psychodramatic techniques	Yes (Specific data)	Quantitative. Pre-post evaluation	No (quasi-experimental)	Death Attitude Profile-Revised (DAP-R); Psychological Well-being Scale (PWBS); Resilience Scale for Adolescents (READ); Self-Transcendence Scale (STS); Testoni Death Representation Scale (TDRS)	IG*CG Fear of death (p <.05); death avoidance (p <.01); Neutral acceptance (p <.05); approach acceptance (p >.05); Psychological Well-being Scale: all subescales (p >.05); Resilience Scale: all subescales (p >.05); Self-trascendence (p >.05); Testoni Death Representation Scale (p >.05)	Fear of death (η2 partial = 0.08); Death avoidance (η2 partial = 0.10); neutral acceptance (η2 partial = 0.06)
[37] Testoni et al. (2018) Italy	IG: 138 Students from a high school where an adolescent student had committed suicide CG: 130 Students from a high school where an adolescent student had committed suicide	Discuss death and associated spirituality and open dialog about and reflections on the afterlife	Morenian Psychodrama	Not specified	Double, soliloquy, role reversal and moviemaking	General information	Quantitative. Pre-post evaluation	No (quasi-experimental)	Testoni Death Representation Scale (TDRS); Toronto Alexithymia Scale (TAS); Personal Meaning Profile (PMP); Death Anxiety Scale (DAS)	IG*CG Death representation as annihilation (p <.001 Alexithymia Total (p <.001); Personal meaning profile (p <.01); Death anxiety (p <.001)	Death representation as annihilation (η2 partial = 0.07); Alexithymia Total (η2 partial = 0.08); Personal meaning Total (η2 partial = 0.04); Death anxiety (η2 partial = 0.05)
[38] Veljkovi et al. (2021) Serbia	IG: 30 Patients with psychotic disorders under pharmacological treatment CG: 30 Patients with psychotic disorders under pharmacological treatment	Improve the quality of life	Morenian Psychodrama	Not specified	Not specified	General information	Quantitative. Pre-posttest evaluation	No (quasi-experimental)	Life Quality Scale in Schizophrenia (QLS)	IG*CG Life quality (p <.001)	Not specified

Table 2.

Psychodrama interventions: qualitative study design

GENERAL DATA		IMPLEMENTATION DATA					EVALUATION DATA		EFECTIVENSS
Author (year) Country	Sample (N intervention group IG and N control group CG)	Intervention objective	Theory	Modality; Intensity, periodicity, and duration	Techniques	Detailed decription of intervention	Study desing	Data collection	Qualitative results
[39] Kamışlı and Terzioğlu (2021) Turkey	IG: 12 Women undergoing in vitro fertilization treatment	Improve psychosocial well-being	Morenian Psychodrama	Group. 10 sessions. Weekly. 3 h each session	Role reversal, double, mirror, scene-setting, and surplus reality	General information	Qualitative. In-session evaluation. Single-group	Observation and Interviews	During the psychodrama, the women expressed that they recognized painful thoughts and feelings related to the past and future without trying to suppress them. Participants were relief of sharing their emotions and hopefulness and setting new goals. During the sharing phase in PGT, they talked about changing situations in their lives and the reactions of their family to those changes. The participants expressed that PGT raised awareness, coping strategies, and hopeful emotion
[9] Maya et al. (2020) Spain	IG: 110 Adolescents with problematic behaviors and parents	Improve behavior and relationships with parents	Psychodramatic Family Therapy based on Scenes (SB-PFT). Systemic therapy combined with psychodrama	Multiple-family group. 10 sessions. Weekly. 2 h each session	Role-playing, mirror, role reversal, double amongst others	General information	Qualitative, Posttest. single-group	Focus groups	Adolescents: increased social support network, change in attitudes contributing to improved family and social adaptation, and key problem-solving skills. Parents: greater expressiveness of emotions and feelings, improved attitude towards accepting family and social norms, and overall enhancement of psychological well-being
[40] Ron and Yanai (2021) Israel	IG: 12 Women victims of domestic violence	Achieve empowerment for women victims of domestic violence	Morenian Psychodrama	Open group. Sessions of 1 h each (one session per week for 12 months)	Role reversal, mirror, double, magic shop, and drawing	General information	Qualitative. In-session evaluation. Observation. Single-group	Verbatim transcripts of therapy sessions	The intervention resulted in the reduction of anxiety, stress, guilt, and self-blame, while reinforcing perceptions of self-worth and confidence

Table 3.

Psychodrama interventions: mixed-methods study design

GENERAL DATA		IMPLEMENTATION DATA					EVALUATION DATA			EFFECTIVENESS DATA
Author (year) Country	Sample (N intervention group IG and N control group CG)	Intervention objective	Theory	Modality; Intensity, periodicity, and duration	Techniques	Detailed decription of intervention	Study desing	RCT	Instruments to evaluate pre-posttest or follow-up	p values	Size effect	Qualitative results
[41] Bucuţă et al. (2018) Romania	IG: 15 Women victims of sexual abuse CG: 18 Women victims of sexual abuse	Enhance spontaneity and well-being to increase empowerment in women	Morenian Psychodrama	Group. 25 sessions. Weekly. 2 h each session	Double, mirror, concretization, role reversal, role-play, encounter, family social atom/corrective atom, empty chair, personification of emotions, sociometry, relaxation techniques, plus-reality/future projection, balcony	Yes (Specific data)	Mixed. Quantitative: Prerest-posttest evaluation. Qualitative: follow-up (3 months and over 5 years after the intervention)	No (quasi-experimental)	Revised Spontaneity Assessment Inventory (SAI-R); Clinical Outcomes in Routine Evaluation Outcome Measure (CORE-OM)	IG*CG: spontaneity (p >.05) personal well-being (p >.05).	Not specified	Women perceived an improvement in areas like trust, hope, self-esteem, empowering, and courage to make decisions and changes
[42] Dogan (2018) Turkey	IG: 14 Undergraduate students in psychological counseling CG: 9 Undergraduate students in psychological counseling	Improve counseling skills, especially empathy and self-awareness	Morenian Psychodrama	Group.12 sessions. Weekly. 3 h each session	Role-play, double, role reversal, double, mirror, drawing technique, amongst others	Yes (Specific data)	Mixed. Quantitative: Pretest-posttest evaluation. Qualitative: Case stud. In-session evaluation, observation, and interviews	No (quasi-experimental)	Empathic Tendency Scale (ETS)	Posttest IG*CG Empathic Tendency (p <.05) Pre-posttest only IG: Empathic Tendency (p <.01)	Not specified	The qualitative findings of the study revealed that psychodrama was an effective method for counselor candidates to improve their self-awareness and helping skills, among which empathy plays a prominent role
[43] Giacomucci and Marquit (2020) United States	IG = 86 Patients with substance addiction and PTSD	Reduce the PTSD symptoms	Therapeutic Spiral Model, and Relational Trauma Repair Model	Group. 8 sessions. 2 sessions per week. 1.75 h and 2.75 h	Not specified	Yes (Specific data)	Mixed. Quantitative: Pretest-posttest evaluation Qualitative: Posttest. Interview.	No (single-group)	PTSD Checklist	Overall PTSD symptoms (p <.001)	Not specified	Most participants felt emotionally safe and connected to others, while agreeing that the services were beneficial, increased hope, facilitated the expression of feelings, and both helped with identifying strengths and managing trauma-related symptoms
[44] Mondolfi and Pino-Juste (2021) Spain	IG: 17 Women victims of gender-based violence	Reduce psychological distress (post-traumatic stress, depression, and anxiety), reduce sexist stereotypes, and improve self-esteem, quality of life, and communication skills	Combination of drama therapy with psychodrama	Group. 20 sessions. Weekly. 2 h each session	Empty chair, psychosomatic roles, collective construction and sociometry	Yes (Specific data)	Mixed. Quantitative: pretest-posttest evaluation. Qualitative: observation and focus groups in each session	No (single-group)	Severity of PTSD Symptoms Scale (PSS-I-4); Quality of Life Survey (SF-12 v1); Ambivalent Sexism Inventory (ASI); Purpose in Life Test (PIL); Beck Depression Inventory II (BDI-II); Rosenberg Self	Pre-Posttest Depression (p <.05) Purpose in life global (p <.05) Other scales: non significant	Not specified	The study highlights the importance of the group experience in recovering from psychological distress and processing psychic trauma. Interaction with other women who had similar experiences helped participants meet therapeutic needs and initial expectations for social and emotional support
[45] Parlak and Oksuz (2021) Turkey	IG: 10 University students in a romantic relationship CG: 10 University students in a romantic relationship	Promote the flexibility of forgiveness	Morenian Psychodrama	Group. 16 sessions. Weekly. 3 h each session	Double, mirror, role reversal, reenactment, cognitive rework, catharsis and surplus reality	Yes (Specific data)	Mixed. Quantitative: Pre-post evaluation and follow-up (six weeks). Qualitative: Evaluation form with open-ended questions in-session.	No (quasi-experimental)	Heartland Forgiveness Scale	Posttest IG*CG Total Forgiveness (p <.05) Pre-Posttest-Follow-up (only IG) Total Forgiveness (p <.05)	Not specified	Rehabilitative effect on levels of forgiveness, empathy skills, and family relationships.The participants gained awareness and courage to understand emotions of the others and themselves. The participants confronted with their emotions, their tolerance of mistakes made by themselves and other people increased, their empathy skill strengthened, and they created awareness towards the importance of expressing their thoughts and feelings
[46] Soysal (2021) Turkey	IG: 13 First-year university students CG: 14 First-year university students	Enhance emotion regulation skills	Morenian Psychodrama	Group. 20 sessions. Weekly. 3 h each session	Role-play, double, role reversal, mirror, surplus reality amongst others	Yes (Specific data)	Mixed. Quantitative: pre-posttest evaluation, and follow-up (three months later). Qualitative: posttest evaluation. Semi-structured interviews with opend-endeed questions	No (quasi-experimental)	Emotion Regulation Questionaire (ERQ)	IG*CG Pret-Posttest-Follow-up Cognitive Reappraisal (p <.01) Suppression (p <.01)	Cognitive Reappraisal (η2 = 0.6) Suppression (η2 = 0.7)	Participants most commonly sought to regulate anxiety, followed by shame, anger, and sadness. Empathy was the skill most improved through the psychodrama process, followed by self-confidence, hopefulness, and patience. Techniques like role-playing and role-reversal were reported as the most effective in improving emotion regulation skills
[47] Terzioğlu and Özkan (2018) Turkey	IG: 30 Infertile women undergoing vitro fertilization	Improve self-esteem, anxiety, depression, and hopelessness levels in women undergoing infertility treatments	Morenian Psychodrama	Group. 8 sessions. Weekly. 3 h each session	Psychodrama games	Yes (Specific data)	Mixed. Quantitative: pre-posttest evaluation. Qualitative: in-session observation, interview, and case-study methods in each session	No (single-group)	Beck’s Depression Inventory; Beck’s Anxiety Inventory, Beck’s Hopelessness Scale; Rosenberg Self-Esteem Scale	Pre-posttest levels of depression, hopelessness and self-esteem (p <.05) Anxiety (p >.05)	Not specified	Participants reported feelings of relief, well-being, increased awareness, development of their abilities, greater ease in talking about infertility, and recognition of their own worth

General data

Twenty-seven articles met the inclusion criteria. Specifically, 17 psychodrama-based interventions were evaluated using a quantitative design (Table 1), 3 interventions were evaluated using a qualitative design (Table 2), and 7 interventions were evaluated using a mixed-methods design incorporating both quantitative and qualitative evaluations. One-third of the studies (n = 9) were conducted in Turkey, followed by Iran (n = 3), Spain (n = 3), Romania (n = 2), Croatia (n = 2), and Italy (n = 2). Bulgaria, Brazil, Lithuania, Serbia, Israel, and the USA each contributed one study to the review.

The total number of participants in the psychodrama interventions included in the review was 971. The study with the fewest participants included 10 participants, while the study with the most participants had 138. A total of 59.2% of the studies (n = 16) included fewer than thirty participants. Nineteen studies focused on the effectiveness of psychodrama with adult populations, eight with adolescent populations, and only one with a child population. The psychodrama interventions were applied to participants with various profiles; clinical populations with substance use, post-traumatic stress disorder, psychotic patients, or children with dyslexia; populations that had experienced stressful events, such as refugees, or women victims of violence; and universal populations, such as high school students, university students, or nurses. No single profile was identified in which psychodrama is used as a therapeutic model; rather, it is applied to diverse populations.

Implementation data

Regarding the objectives of psychodrama interventions, a wide diversity was observed. If the intervention was applied to a clinical population, its main objective was symptom reduction. For example, in patients with post-traumatic stress disorder, the goal was to reduce symptoms associated with the traumatic event. If the intervention was applied to a universal population, such as university students, the objectives were related to improving their well-being or specific skills like emotional regulation.

Regarding the theory on which the intervention is based, 59.2% (n = 16) were based on Morenian Psychodrama, five interventions did not specify their theoretical framework, two combined psychodrama with systemic theory, and two combined psychodrama with drama therapy. Other interventions were based on various theories such as the Therapeutic Spiral Model or Psychodrama by Alfons Aichinger and Walter Holl.

Regarding the implementation, all psychodramatic interventions were group-based, although three interventions were based on multi-family groups. The number of sessions per intervention ranged from 4 to 25. Specifically, 25.9% (n = 7) of the interventions had 10 sessions, 55.5% (n = 15) included between 8 and 13 sessions, while almost a third of the interventions (n = 8) included between 16 and 25 sessions. Regarding frequency, 70.4% (n = 19) of the interventions were implemented weekly, while 3 interventions were implemented twice a week. Finally, regarding the duration of the sessions, they ranged from 45 min to 4 h. A total of 37% of the interventions (n = 10) had sessions lasting two hours, while 25.9% (n = 7) of the interventions had sessions lasting three hours. Overall, 77.8% of the interventions (n = 21) had sessions lasting between 90 min and three hours. Four interventions did not specify the session duration.

Regarding psychodramatic techniques, more than 15 different techniques were identified, most of them related to role-playing situations. The most commonly used techniques, applied in more than a third of the interventions, were role reversal (n = 12), mirror (n = 11), and double (n = 10). Other techniques used in approximately 10–20% of the interventions (n = 3–5) included the empty chair, soliloquies, artistic techniques such as drawing, or surplus reality. Eight studies did not specify the psychodramatic techniques used in the interventions.

Regarding the detailed information reported in the papers about the implementation of the intervention, 40.7% of the studies (n = 11) only reported general information such as the number of sessions, frequency, duration, or techniques, while 59.2% of the studies (n = 16) provided specific details, for example, session objectives or summaries of how each session was conducted. Notably, there was no mention of any manuals that structured the implementation of the sessions.

Evaluation data

Regarding the evaluation design used to measure the impact of the interventions, only three studies (11.1%) implemented a Randomized Controlled Trial (RCT) design. A total of 48.1% (n = 13) used a quasi-experimental design with a comparison group, while 40.1% (n = 11) used a single-group design without a control group.

In terms of assessment timing, 63% (n = 17) of the studies employed a pretest-posttest evaluation. Seven out of the 27 studies (26%) included a pretest-posttest-follow-up evaluation. There was significant variation in the timing of the follow-up assessments, ranging from six weeks to five years after the intervention concluded. However, except for the study that conducted the follow-up five years post-intervention, the follow-ups were carried out between six weeks and six months after the intervention. Additionally, six studies (22.2%) included session-by-session evaluations through observation or semi-structured interviews with open-ended questions.

Regarding the instruments used to measure the effectiveness of the interventions, more than forty different instruments were employed, tailored to the objectives of each intervention. Notably, there was an absence of psychodrama-specific instruments to measure the central concepts of the model, such as spontaneity. This measurement was only included in one study.

Effectiveness data

Regarding the data analysis conducted in RCT or quasi-experimental designs (n = 16), it was notable that thirteen studies included comparisons between the intervention group and the control group, as well as the interaction over time between pretest, posttest, and follow-up when applicable. Two studies conducted comparisons only at the posttest, while one intervention did not study this comparison. Of the 15 interventions that compared data from the intervention and control groups over time, seven found effectiveness across all dimensions with p-values < 0.05, four found significant impact in some dimensions but not others, and four studies found no significant changes. No study reported iatrogenic effects from psychodramatic interventions.

Regarding the single-group designs that incorporated quantitative pretest-posttest evaluations (n = 8), two studies found positive and significant results across all evaluated dimensions, four interventions showed significant changes in some dimensions but no changes in others, and two studies found no benefits from the psychodramatic intervention. No iatrogenic effects were found in these studies.

Regarding effect size, this statistic was reported in 11 studies and not reported in 13 of the 24 studies that conducted a quantitative evaluation. The most used statistic was η2 partial in four studies, Cohen’s d was used in three articles, η² in two articles, Glass’s delta in one article, and one article did not specify the statistic used. Among the dimensions that showed significant results and were also measured for effect size, two dimensions had a small effect size, eight dimensions had a medium effect size, nine dimensions had a large effect size, and six dimensions had a very large effect size.

Psychodramatic interventions were shown to be effective in improving various dimensions: emotional awareness in nurses, emotional intelligence and antisocial behavior in adolescents, quality of life in patients with psychotic disorders, reduction of PTSD symptoms in patients with PTSD and substance use, or improvement in psychotic symptoms and quality of life in patients with schizophrenia, among other dimensions and populations. However, in other dimensions, no positive effects were observed, such as in the improvement of traumatic symptoms in refugee children and parents, reduction of burnout and improvement of coping strategies in nurses, improvement of quality of life in nursing students, or in women who are victims of domestic violence and sexual violence, among others. No clear pattern was observed regarding the profiles, objectives, and dimensions where psychodrama shows positive effects versus those where it does not.

Regarding qualitative evaluation, in the 10 studies that incorporated a qualitative assessment of the interventions, participants consistently reported positive changes across a wide variety of dimensions. For example, reductions in anxiety and guilt in women victims of domestic violence, less anger and anxiety in university students, greater well-being in infertility situations, or better communication between parents and adolescents with problematic behaviors, among other outcomes.

In summary, out of the 27 psychodrama interventions that met the inclusion criteria, five (18.5%) did not report any positive effects, while in the remaining 22 (81.5%), positive impacts of psychodrama on at least one targeted dimension were reported, either quantitatively or qualitatively.

Discussion

Psychodrama has been used in psychotherapy, particularly in group psychotherapy, for more than 100 years [48]. This systematic review represents one of the most ambitious reviews in psychodrama to date, both in terms of objectives and the number of studies included. This review not only examines the effectiveness of psychodrama but also its main implementation characteristics. It is in line with the objectives of the review conducted by Orkibi and Feniger-Schaal [15], who studied psychodrama interventions up until 2017. This review updates the current state of psychodrama interventions from 2018 to 2022. The main findings, consistent with Orkibi and Feniger-Schaal [15], confirm the need to increase the number of RCT studies in psychodrama, which remain scarce. However, due to ethical considerations with certain populations, it is difficult to develop RCTs, but efforts should be made to at least implement quasi-experimental study designs. In this review, RCT or quasi-experimental designs were used in only 59.2% of the cases. To support evidence-based interventions, this requirement is fundamental [49]. Therefore, psychodrama as a model must continue to work on improving its evaluation designs.

Furthermore, to meet the requirements for evidence-based interventions, the evaluation design should include quantitative assessments at pretest, posttest, and follow-up. In this review, we found that only 26% of the studies included follow-up evaluations to determine whether the changes were maintained, consolidated, improved, or worsened over time [e.g., 30, 31, 35]. Therefore, it remains essential for psychodrama-based interventions to incorporate long-term evaluations of effects. Along these lines, it is also important to use validated and culturally adapted assessment instruments, and to ensure that the results show significant changes in the expected direction with a large effect size [49].

Regarding assessment instruments, this review highlights the variety of instruments specific to the objectives of each intervention. However, it also emphasizes the absence of psychodrama-specific instruments to measure constructs such as spontaneity or creativity, which are two central constructs of Morenian Psychodrama [5]. Spontaneity and creativity are the foundation of Morenian psychodrama; however, except in one study [41], specific psychodrama scales, such as the Revised Spontaneity Assessment Inventory, have not been used [50]. This poses a challenge for the development of rigorous evaluations of the psychodramatic model, in which the core constructs of Morenian psychodrama theory are measured [5].

Regarding the effectiveness of the interventions, positive results were obtained. In 81.5% of the interventions, changes were observed in some of the targeted objectives, although approximately 30% of the interventions reported positive changes in some dimensions but not in others. In contrast, 18.5% of the interventions did not show any positive results, though no iatrogenic effects were reported either. Qualitative studies tend to give a more favorable view of psychodrama when changes are evaluated through interviews with clients. This review does not clarify whether psychodrama is more effective with one population or another, given that positive results were observed across a wide range of populations, objectives, and modes of implementation. For example, improvements were seen in post-traumatic symptoms in pre-adolescents or adult patients with substance abuse [26, 43], reduction in anxiety or aggression in adolescents with ADHD [31], improvement in quality of life in patients with psychotic symptoms [32, 38], enhancement of empathy in university students [42], or reduction of depression in women victims of domestic violence [44], among other outcomes.

With regard to the significance and generalization of changes, effect size was reported in 11 of the 24 quantitative studies. For interventions to be considered evidence-based, it is not enough to identify significance in terms of p-values; effect size must also be reported to assess the practical relevance of the results. Although in the incorporated review most of the studies that measured effect size found medium-to-large effect sizes [e.g., 26, 37, 46], the sample sizes of the studies were very small, with nearly 60% of the studies including fewer than 30 participants in the intervention group [e.g., 23, 24, 41]. For this reason, these results should be interpreted with caution, and there is still a need to increase sample sizes in psychodrama interventions while also reporting the effect sizes of these interventions.

This review shows positive results across a wide variety of clients, ranging from universal populations where psychodrama is applied in universities or high schools to indicated populations with clinical symptoms. Only one intervention was implemented in a child population, with psychodrama being more frequently implemented in adolescent and, especially, adult populations. Currently, there remains limited evidence on psychodrama in children. It may be necessary to expand the theoretical framework for applying interventions to child populations [51]. Additionally, with children, the use of drama therapy appears to be more common [52].

Regarding implementation, it is notable that most interventions are based on Morenian Psychodrama as opposed to other current theories of psychodrama such as the Rojas-Bermúdez model [2], or the application of psychodrama in combination with another model like systemic therapy [9]. Eight interventions did not specify the theory on which they were based. However, we hypothesize that these interventions are also supported by Morenian Psychodrama, as if a different theory were applied, it likely would have been mentioned. Regarding the techniques used in psychodrama sessions, the articles report different techniques, with some of the most utilized being those identified in the systematic review by Cruz et al. [13]: role reversal, double, or mirror. These three techniques are confirmed as the most commonly used techniques in psychodrama interventions. These three techniques have been frequently used in Morenian Psychodrama for the dramatization of conflicts or interpersonal relationships [5]. Additionally, another set of techniques appears in various interventions, such as the empty chair, soliloquies, artistic techniques such as drawing, or surplus reality. Another relevant finding is that 100% of the studies correspond to evidence of group treatments when psychodrama can currently be implemented in individual treatments [11]. According to the standards of evidence-based treatments [14, 53], it is important that interventions are structured and manualized. None of the interventions included in the review referenced being based on a manual. 40.7% of the studies only reported general information such as the number of sessions, frequency, duration, or techniques, while 59.2% of the studies provided specific details, such as session objectives or summaries of how each session was conducted. According to Orkibi and Feniger-Schaal [15], there is a need for improved methodology and transparency in future studies. The theoretical model of Moreno’s psychodrama, based on spontaneity, makes it difficult to manualize specific treatments. We propose that although not all implementation processes are detailed, psychodramatic treatments should establish certain aspects such as the phases of the sessions (warming-up, dramatization, and sharing), techniques that can be used depending on the problematic, or standardized procedures for the use of techniques.

Limitations

This review has a number of limitations. First, only scientific articles written in English were selected. Second, only primary studies corresponding to peer-reviewed scientific articles were reviewed, excluding other types of publications such as books or doctoral theses. Third, the minimum of 10 participants as an inclusion criterion has excluded other interventions (e.g., [54, 55]), and single-case studies (n = 1) that could have provided more information on the current state of psychodrama and the psychodrama in individual format. Finally, we did not present efficiency data by gender, number of sessions, or in combination with other approaches, which will pose a challenge for future research [43].

Conclusions

The results support the effectiveness of psychodrama across various populations; however, there is a lack of standardization of psychodrama as a model or method for a specific population, problematic, or disorder. It is noteworthy that all psychodrama interventions are conducted in a group. Consequently, there is no reporting on recent evidence of psychodrama at an individual or couples’ level, though multiple-family interventions are mentioned. Morenian Psychodrama continues to be the main theoretical model underpinning the interventions, although many studies provide scant details on theoretical aspects. Regarding implementation, group sessions typically last two hours, and most interventions last between 8 and 13 sessions, with role reversal, double, and mirror being the main techniques; thus, dramatization is positioned as the central element of psychodrama.

In terms of evaluation design, quantitative, qualitative, and mixed designs are reported, but there is a need for an increase in RCT designs, follow-up assessments, and the reporting of effect sizes. Additionally, the use of structured manuals for interventions in specific populations could help psychodrama be considered an evidence-based treatment for particular groups. So far, based on the data from this review, we can say that psychodrama is effective in improving quality of life in different populations, especially among adolescents and adults. However, there are also other interventions that do not report significant positive outcomes. No conclusive profile has been observed in which psychodrama is definitively effective, nor a conclusive profile where it is not. Therefore, in terms of research, psychodrama’s effectiveness studies should be consolidated, and its components—such as the techniques responsible for patient improvement—should be identified.

Author contributions

Maya, Jesús: Designed the study, wrote the protocol, created search strategies, evaluated the quality of included trials, data extraction, wrote the first draft of manuscript, supervised the research, revised the draft of the manuscript. Pérez-Berbel, Miriam: Designed the study, wrote the protocol, performed literature searches, conducted literature searches, data extraction, data analysis, and study selection, evaluated the quality, wrote the first draft of the manuscript. Giraldo-Arroyave, Laura: created the tables, revised the draft of the manuscript. Hurtado, Irene: created the tables, revised the draft of the manuscript. All authors consented to the preparation and publication of the article.

Funding

No funding was received.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Competing interests

The authors declare no competing interests.

Consent to participate

In systematic reviews, consent to participate is not required.

Declarations

The authors declare that they used AI to improve the scientific English.