This quasi-experimental study was conducted in 2023 on children aged 6 to 12 years with cancer admitted to the hematology department of a teaching hospital in Zahedan. Following a similar study by Fazelnia and Hosseini (
21), the sample size was estimated to be 13 participants with a 95% confidence interval using the following formula:
However, considering the possibility of participant dropout, the sample size was increased to 35 individuals per group (
21). A total of 70 children were selected using convenience sampling. Initially, data were collected from participants in the control group, with the first 35 children assigned to this group. After conducting the post-test for the control group, participants for the intervention group were selected. Inclusion criteria included being aged 6 - 12 years, having attended at least one chemotherapy session, suffering from leukemia, possessing a mobile phone or tablet, and not having a mental disability, hearing impairment, or other chronic diseases. Exclusion criteria included absence or non-participation in more than one session, death, or illness of the child.
A demographic information questionnaire was used to assess the children's demographic characteristics (gender, age, duration of illness, frequency of chemotherapy, type of cancer, family history of cancer) and the demographic information of the caregiver parent (age, education, marital status, place of residence, and ethnicity). Additionally, the Coopersmith Self-esteem Inventory (CSEI) (1967) was used to measure the general self-esteem level of the children. The instrument contains 58 items and 4 main subscales (general, social, family, and academic self-esteem) along with a lie detector. Items 4, 8, 9, 14, 19, 20, 27, 28, 29, 33, 37, 38, 39, 42, 43, and 47 are scored as 1 (yes) or 0 (no). The remaining items are scored in reverse (yes = 0 and no = 1), resulting in minimum and maximum scores of 0 and 50 (excluding the lie detector).
The reliability of the inventory was assessed by Ivarsion, with a Cronbach’s alpha value of 0.87 for the entire scale, and corresponding values of 0.80, 0.84, 0.64, and 0.71 for the general, family, social, and academic subscales, respectively. Additionally, the correlation between the inventory scores and the scores obtained from its administration was 0.81, confirming the instrument's validity (
22). Khaledian et al. confirmed the instrument's reliability with a Cronbach’s alpha of 0.88 (
23). In the present study, the instrument's reliability was confirmed with a Cronbach's alpha of 0.82.
After familiarizing themselves with the children and their parents and obtaining informed consent, the study's objectives and intervention procedures were explained to both the children and their parents. Parents were assured of the intervention's safety and the confidentiality and anonymity of their information. Participants were informed that they could withdraw from the study at any time. Initially, the questionnaires were administered to the control group participants as a pre-test, and two weeks later, the self-esteem inventory items were completed as a post-test through interviews with the child in the presence of their parents.
Following the completion of the post-test for the control group, participants for the intervention group were selected. After conducting the pre-test, the intervention group attended sessions held over two weeks. Two intervention sessions were conducted per week, each lasting one hour in the hematology department's playroom, using a mobile app developed by the researcher. Children's songs were played in the playroom to welcome the children and capture their attention. To encourage participation and cooperation, children were given interesting and funny masks and hats themed around their favorite cartoons to wear during the intervention.
During each session, children sang various funny songs, listened to and repeated different sounds of children's laughter, watched humorous and comedy clips suitable for school-age children, and listened to music themed around jokes and laughter for 30 minutes. These activities were embedded in the application. Subsequently, the children participated in happy and fun competitions. To motivate participation and active involvement, they received gifts such as humorous poetry books, funny caricature stickers, or humorous masks.
In the next phase, children played games within the application under the researcher's supervision. The application contained four games and seven sections. The first section featured balloons that played funny sounds of children's favorite cartoon characters, such as Party Kid, Kolah Ghermezi and Pesar Ammeh Za (an Iranian fictional puppet character), SpongeBob SquarePants, Patrick, Pat and Matt, and Pink Panther. Children were tasked with identifying the character whose sound was playing on the moving balloons on the app screen and bursting the balloons. When the balloons burst, laughter was heard from the app. Bursting balloons helped children with cancer express their feelings about facing cancer and its treatment, symbolically bursting and destroying tumors.
In the second game, cancerous and healthy cells were displayed, and the child destroyed the cancerous cells by throwing arrows to replace them with healthy cells. When cancer cells were destroyed, the app played sounds of laughter and happiness. The game was designed as a gyroscope to prevent fatigue, with the arrow-throwing ship moved by tilting the phone screen.
The third part of the app focused on nursing Little Danny. In this section, the challenges faced by children with cancer during chemotherapy were depicted on Little Danny, and children were asked to make Little Danny happy by solving his problems and winning the game. For example, one challenge is hair loss. In the third game, Little Danny's hair fell out, and children were instructed to put hair or a hat on him according to their preferences to make Danny happy. Children were also advised that they could use hats and wigs during treatment to maintain their self-esteem. There were three hairstyles, hats, and wigs in six different colors (18 styles in total), which the child could place on Little Danny’s head. After putting on the hair or wig, Little Danny laughed, and the child won the game.
The second section of the third game addressed anorexia in children with cancer, with the task: "Little Danny has lost his appetite, give him his favorite foods". A diet suitable for children with cancer was selected from reference books. These foods were associated in Little Danny's mind, and the child provided them to solve the problem of anorexia and make Little Danny happy. In the third section, Little Danny experienced pain due to cancer, and the child had to distract him and make him happy by playing cheerful and funny songs. The fourth section focused on issues such as fatigue and impatience, common in children with cancer, with the prompt: "Little Danny is tired and bored. Play funny cartoons for him to make him happy". Consequently, cartoons like SpongeBob SquarePants, Boss Boy, and Party Kid were played from the app. The suitability of these cartoons and songs for this age group was confirmed by an expert and two staff members from the Institute for the Intellectual Development of Children and Young Adults.
The children learned the instructed content and, by simulating their situation with Little Danny's, attempted to implement these practical and important instructions during their illness. The fourth part of the game featured a game phone, where happy and funny songs and poems were played by dialing the phone numbers of children's favorite cartoon characters. The phone ringing sound was laughter. Two weeks after the last session, the questionnaire was completed through interviews with the children in the presence of their parents.
To comply with ethical protocols, laughter therapy sessions were also conducted for the children in the control group, and the application was installed on their mobile phones or tablets. The normality of the collected data was assessed using the Shapiro-Wilk test. Data analysis was performed with SPSS version 27 software, utilizing descriptive statistics and inferential statistics (paired samples t-test for intragroup comparisons, independent samples t-test for intergroup comparisons of variables, chi-square test, and Fisher's exact test). A significance level of 0.05 was used for data analysis.