TABLE 3.

Baseline and outcomes of included study (N = 29).

Author	Item	Evaluation tool	Baseline	Outcome	Attitude
(Meiri et al., 2016)	Anxiety	VAS	The mean number of blood examinations: Intervention group: 2.48 ± 1.80 EMLA group: 2.88 ± 2.63 Control group: 1.90 ± 1.34 There were no differences between the groups, and there was a generally significant negative correlation between the number of previous blood exams and anxiety in the current exam (r = −0.25, p = .012).	The intervention group was significantly lower with clown than in the control group or EMLA (2.6 ± 1.2 vs. 3.7 ± 1.3 or 3.8 ± 1.6, p < .01 for both).	Positive
(Dionigi et al., 2014)	Anxiety	m‐YPAS	Intervention group: 50 (23−97) Control group: 33 (23−97)	Intervention group: 33 (23−83) Control group: 43 (23−100) Pre‐post = 0.002; group = 0.004 ( p < .01)	Positive
(Liguori et al., 2016)	Anxiety	m‐YPAS	The initial mean (SD) m‐YPAS scores were 37.3 (21.7) and 37.1 (13.8) for the experimental and control groups, respectively.	The mean (SD) difference between the m‐YPAS score at the first and second measurements of each participant was −2.8 (7.2) in the experimental group and 10.7 (10.8) in the control group. The 13.5‐point difference between these averages was statistically significant ( p = .003).	Positive
(Goldberg et al., 2014)	Anxiety	STAI	Intervention group: 30.3 ± 5.4 Control group: 33.6 ± 5.7 p = .1	A significant reduction in state‐STAI was found in the clowns group (27.1 ± 4.2), when compared with the regular group (34.3 ± 7.6), p = .002, p < .05.	Positive
(Felluga et al., 2016)	Anxiety	CAPS	Intervention group: 2 (1−3) Control group: 2 (0−3) p = .759	Anxiety during the medical care, a significant reduction in CAPS was found in the clowns group (1 (0−2)), when compared with the control group (2 (0−3)), p = .013, p < .05.	Positive
(Kocherov et al., 2016)	Anxiety	m‐YPAS	There was no difference between the children's ages in both groups (p = .732).	The patients from the intervention group demonstrated a lower preoperative anxiety index upon ( p = .0319) and after surgery ( p = .0042)	Positive
(Tener et al., 2016 )	Anxiety	Using an in‐depth semistructured interview guides, one for the parent and another for the child.	A purposive sample of nine children, six undergoing an endoscopic examination and three an anogenital examination and their accompanying parents (six mothers and three fathers) were invited to participate in in‐depth interviews. The Children's ages ranged between 5 and 16 (average 9.7 years).	The study indicates that with a medical clown, the anogenital examination and the whole medical encounter are perceived not only as less frightening and less distressing by the child and family, but may even become a positive empowering experience, shaping perceptions toward the hospitalization experience, as well as the life narrative.	Positive
(Agostini et al., 2014)	Anxiety	STAI(Y‐I)	Waiting room: Intervention group: 43.76 ± 11.45 Control group: 46.04 ± 11.67	After the separation: the results showed that maternal state anxiety scores significantly changed over time. ( p = .0001) Intervention group: 35.36 ± 8.96 Control group: 38.44 ± 7.37	Positive
(Kurudirek et al., 2021)	Anxiety	CFS	CFS: 10 min before blood sampling Intervention group: 3.39 ± 0.62 Control group: 3.57 ± 0.76 p = .098.	CFS: During blood sampling (p = .000) Intervention group: 2.04 ± 0.96 Control group: 3.65 ± 0.67 CFS: 10 min after blood sampling (p = .000) Intervention group: 0.01 ± 0.10 Control group: 1.84 ± 1.37 Differences between intervention groups: p = .000 Differences between control groups: p = .000	Positive
(Cai et al., 2014)	Depression Anxiety	BDI STAI	At the pretreatment assessment, there were no statistically significant differences between two groups with respect to demographic characteristics. The pretest mean scores revealed no significant differences (p > .05) between the two groups in the parameters at baseline.	There was a decrease in the depression (F(1,28) ¼ = 18.89; p < .005) and anxiety (F(1, 28) ¼ = 27.11; p < .005) scores in the humor group from pretest to posttest.	Positive
(Rudnick et al al., 2014)	Depression Anxiety	PANAS	The three study arms showed no significant demographic or clinical (diagnostic and other) differences at baseline (F (2, 32) = 1.01, p = .375 for age; F (2, 32) = 1.16, p = .325 for years of education; F (2, 32) = 0.80, p = .459 for length of psychiatric illness; F (2, 32) = 0.680, p = .514 for number of psychiatric hospitalizations).	There was no significant difference in attrition between the study arms (FET = 3.77, p = .183). Reliabilities of all outcome measures were satisfactory.	Neutral
(Tagalidou et al., 2019)	Depression Anxiety	STAI CESD	There were no differences in demographic variables between the intervention and wait list control groups. In addition, two groups had no differences in baseline measures.	The ITT analysis revealed no significant group by time interaction for any outcome: Depression (F (2, 64.86) = 1.18, p = .315); Anxiety (F (2, 66.53) = 0.56, p = .575) Depression and anxiety showed no effects at all. Post hoc tests did not show significant effects for the training group from pre to post or pre to follow‐up.	Neutral
(Bressington et al., 2019)	Depression Anxiety	DASS	Analysis of participants’ baseline demographic and characteristics revealed no statistically significant differences between the two groups (p > .05).	Depression: The outcome measure results indicated that the LT group had a statistically greater decrease in depression (DASS21—Depression scale) than the control group from baseline to immediately following the intervention (B = −5.123, 95% CI: –9.527 to –0.72; p = .023). However, there was no significant difference in the change in depression from baseline to 3‐month follow‐up between the two groups (B = –2.724; 95% CI: −7.106 to 1.658; p = .223). Anxiety: There were no significant differences in changes in anxiety (DASS21—Anxiety scale) between groups from baseline to the first follow‐up (B = −3.256, 95% CI: –7.309 to 0.258; p = .068) or second follow‐up (B = −2.321, 95% CI: –6.458 to 1.816; p = .271).	Positive
(Shahidi et al., 2011)	Depression	GDS	The baseline outcomes between the three groups were also not significantly different.	The analysis revealed a significant difference in the decrease in depression scores of both the Laughter Yoga and exercise therapy group in comparison to the control group ( p < .001 and p < .01, respectively). Laughter therapy: Pretest (mean ± SD): 16 ± 5.3; Posttest (mean ± SD): 10 ± 6.9 Control: Pretest (mean ± SD): 15.2 ± 3.9; Posttest (mean ± SD): 15.2 ± 6.1	Positive
(Kim et al., 2015)	Depression	POMS‐B	Baseline demographic and clinical characteristics for the two groups did not differ at the 5% significance level. Before Laughter Therapy (p = .609) Intervention group: 5.15 ± 4.49 Control group: 5.69 ± 3.65	Pre‐ and Postlaughter therapy: Intervention group: −2.30 ± 3.84 Control group: −0.17 ± 3.52 (p = .023, p < .05)	Positive
(Lee et al., 2020)	Depression	BDI	No significant differences were observed when we compared the demographic and clinical characteristics of the laughter and control groups. Furthermore, the preprogramed evaluations revealed that the laughter and control groups had similar levels of stress, depression, and HRQOL.	Relative to the control group, the laughter group exhibited significant improvements in the scores for depression (p¼ .025). Furthermore, the laughter group also had a significantly lower incidence of depression based on the scores from Beck's Depression Inventory (p ¼ .047). A significant improvement was observed in the laughter group for the mild depression subgroup (p ¼ .009).	Neutral
(Genc & Saritas, 2020)	Anxiety	STAI	The results show no statistically significant difference between the patients’ gender, age, marital status, disease diagnosis or level of education in control and intervention groups. The pretest of STAI scores and vital signs were similar in both groups (p > .05).	The difference between the mean anxiety scores of the two groups was statistically significant (p = .03, p < .05). Intervention group: 43.36 ± 9.76 Control group: 47.13 ± 5.76 The pretest anxiety scores of the individuals in the experimental group decreased from 49.84 ± 8.16 to 43.36 ± 9.76 after watching the video, and the difference between these scores was found to be significant(p < .001).	Positive
(Bega et al., 2017)	Depression Anxiety	Neuro‐QoL	No significant differences were observed when we compared the demographic and characteristics of the intervention or control groups. Anxiety (p = .115) Intervention group: 16 (12, 20) [8, 25] Control group: 20 (16, 25) [9, 33] Depression (p = .064) Intervention group: 12 (10, 17) [8, 20] Control group: 16 (13, 21) [9, 26]	Anxiety (p = .380) Pre: 16 (14, 20) [8, 25] Post: 17 (12, 20) [8, 30] Change: −1 (4, 1) [8, 8] Depression (p = .128) Pre: 13 (11, 20) [8, 26] Post: 12 (9, 16) [8, 24] Change: −1.5 (4, 0) [10, 7] There was no significant improvement in anxiety and depression (p > .05).	Positive
(Bennet et al., 2020)	Depression Anxiety	PHQ‐4	There were no differences at baseline on demographic characteristics between groups.	The proportion of patients with self‐reported depressive symptoms changed from 17 (22%) to 16 (20%), in control and from 11 (17%) to 5 (8%) in the intervention, respectively ( p = .04). In the control arm, 7 out of the 17 patients with self‐reported depressive symptoms at baseline continued to report depressive symptoms at follow‐up compared to the intervention arm where only 1 of 12 patients continued to report depressive symptoms. No differences were noted between the groups for reported anxiety.	Positive
(Armat et al., 2022)	Depression Anxiety	BDI BAI	Statistical tests showed that the groups were still balanced in terms of age, height, weight, marital status, and educational level.	Depression and anxiety levels were measured at study initiation, week 4, and week 8 in both groups. Results showed a significant difference in the pattern of depression ( p < .001) and anxiety ( p < .001) scores within and between groups. The trend of changes in depression score is moderately ascending in the control group, whereas it is sharply descending in the intervention group.	Positive
(Ko et al., 2022 )	Depression Anxiety	CESD BAI	The baseline outcomes between the two groups were also not significantly different.	Outcomes were measured right after the completion of the intervention and 2 weeks later. The levels of acculturative anxiety and depression decreased right after the intervention compared to the baseline, and the effects were sustained after 2 weeks ( p < .001, p < .001, respectively).	Positive
(Kiyak & Kocoglu, 2021)	Depression Anxiety	STAI BDI	The baseline depression, state anxiety, and trait anxiety mean scores of the IG and CG were similar.	Depression (8.44 ± 6.43) and trait anxiety scores of the IG (45.63 ± 5.05) were lower than the CG (11.57 ± 8.57; 47.93 ± 4.91) and the effect size was small (d = 0.35 for depression; d = 0.17 for trait anxiety). Group × time interaction was significant for depression (F = 99.563, p < .001) and trait anxiety (F = 5.441, p = .021).	Positive
(Ko & Youn, 2011)	Depression	GDS	There were no significant differences in baseline characteristics between the two groups. Before laughter therapy, the GDS scores were as follows: Laughter therapy group: 7.98 ± 3.58 Control groups: 8.08 ± 3.96	After laughter therapy, the GDS scores were laughter therapy group:6.94 ± 3.19 ( p = .027) control groups: 8.43 ± 3.44( p = .422). ANCOVA, controlling for preexperimental GDS score and other variables, showed statistical significance in the effect of laughter therapy on GDS ( p = .011).	Positive
(Heidari et al., 2020)	Depression	Elderly's Depression Questionnaire	There were no significant differences in baseline between the two groups.	The mean scores of depression in the intervention group after LT (M = 2.57) were lower than those before the intervention (M = 6.87) (95% CI = −5.58 to −3.02) and also the results of independent t‐test showed a statistically significant difference before and after the intervention between the two groups ( p < .001).	Positive
(Ghodsbin et al., 2015)	Depression Anxiety	GHQ‐28	There were no significant differences in baseline between the two groups.	We found a statistically significant correlation between the laughter therapy program and factors such as anxiety (Pre: 7.83 ± 4.74, Post: 3.84 ± 2.77, p = .001). However, there was no statistically significant correlation between the laughter therapy and depression ( p = .069).	Positive
(Low et al., 2014)	Anxiety	BEAM	There were no differences at baseline in demographic characteristics between groups. IG residents were rated at baseline as having a longer duration of active disengagement and a shorter duration of happy effect.	Over time, there were also significant overall decreases in the duration of anxious. The IG had increased high positive behavior ( p¼ .017) and decreased active disengagement ( p¼ .008) and angry mood ( p¼ .033) in comparison with controls.	Positive
(Brodaty et al., 2014)	Depression Anxiety	CSDD NPI‐NH	There were no differences in baseline measures between the two groups. Assessments were performed at baseline, week 13, and week 26.	Depression: Laughter Boss Commitment was associated with higher resident engagement that in turn was associated with decreased depression scores. Similarly, higher management support score predicted higher Laughter Boss Commitment scores, thereby ultimately affecting resident engagement and CSDD scores. The model fit for CSDD was acceptable ( c2 / df ¼ 1.68, RMSEA ¼ 0.06, CFI ¼ 0.92). Anxiety: Laughter Boss Commitment ratings were associated with resident engagement, which was associated with a decrease in NPI‐NH scores over time. The fit statistics indicated adequate model fit ( c2 /df ¼ 0.74, RMSEA < 0.001, CFI ¼ 1.00).	Positive
(Low et al., 2013)	Depression Anxiety	CSDD CMAI	There were no significant differences on demographic characteristics between the groups. Intervention group residents were taking slightly more regular psychotropic medications on average.	Depression decreased over time. The group by time interaction was significant for agitation measured using the CMAI, before and after adjustment for covariates ( p < .05). The humor therapy group decreased on the CMAI by 0.17 (95% CI 0.004 to 0.34; p = .045) points more than controls between baseline and follow‐up.	Positive
(Ozturk & Tezel, 2021)	Depression Anxiety	BSI	There were no differences in baseline measures between the two groups.	Evaluation of the mean scores obtained in BSI subdimensions (i.e., anxiety, depression) before and after the intervention showed a significant decrease in the scores of the IG compared with the CG ( p < .05). Anxiety (pretest): IG: 1.08(0.47); CG: 1.02 (0.61) Anxiety (posttest) IG: 0.67 (0.50) CG: 0.84 (0.58) p < .001 Depression (pretest) IG: 1.34 (0.57); CG: 1.33 (0.69) Depression (posttest) IG: 0.89 (0.55); CG: 1.25 (0.57) p < .004	Positive