Methods

This study involves the development of an educational technology. It was conducted in accordance with the ethical standards outlined in Resolution 466/2012 of the National Health Council of the Ministry of Health and was approved by the Research Ethics Committee (CAAE: 55114821.6.0000.5374). Financial support was provided by the São Paulo Research Foundation (FAPESP; Grant number: 2022/02599-6), which funded only the research-related costs. The funding agency had no role in the design of the study, data collection, analysis, interpretation, manuscript preparation, or the decision to submit the article for publication.

The validation of the comic book involved an invitation extended to 31 expert judges and 62 representatives of the target audience, who were caregivers responsible for feeding children aged 0 to 5 years. The selection of expert judges was based on curriculum analyses available on the Lattes Platform (http://lattes.cnpq.br/), an integrated database of individual researchers and Brazilian institutions, supervised by the National Council for Scientific and Technological Development (CNPq). Inclusion criteria required that candidates meet at least two of the following requirements: a minimum of 10 years’ experience in child-focused health promotion or prevention activities; scientific publications related to food health and/or childhood obesity; participation in the development and validation of educational materials; and possession of a master’s or doctoral degree with scientific output in the fields of nutrition, collective health or pediatrics. Representatives of the target audience were recruited by convenience sampling in the waiting room of a private pediatric clinic in Lavras, Minas Gerais (MG). To be eligible, participants had to be responsible for feeding at least one child aged 0 to 5 years.

The study was conducted in four phases:

1. 1 – Script creation:

The story script was developed after reviewing the literature and consulting guidelines published by the Brazilian Society of Pediatrics⁽³³⁾ and the Ministry of Health.⁽³⁴⁾ The narrative follows a character who, after a typical day, wakes up the next morning, looks into the mirror, and finds that her appearance has changed. Seeking answers, she visits a friend, who helps her recall the healthy eating practices her family has followed. The script emphasizes key aspects of food health, including maternal nutrition during pregnancy,^{(Reference Fisk, Crozier, Inskip, Godfrey, Cooper and Robinson35,Reference Ouyang, Cai and Wu36)} exclusive breastfeeding until six months of age,^{(Reference Hossain and Mihrshahi37,Reference Onyango, Kimani-Murage and Kitsao-Wekulo38)} the introduction of all food groups during complementary feeding,^{(Reference Snetselaar, de Jesus, DeSilva and Stoody39,Reference Soriano, Ciciulla and Gell40)} the exclusion of processed and ultra-processed foods,^{(Reference Khoury, Martínez and Garcidueñas-Fimbres41–Reference Petridi, Karatzi, Magriplis, Charidemou, Philippou and Zampelas43)} and the importance of healthy snacks during the school year.^{(Reference Correa-Burrows, Rodríguez, Blanco, Gahagan and Burrows44,Reference Jamaluddine, Akik and Safadi45)}

1. 2 – Preparation of the initial version of the comic book (illustrations, layout, design):

Based on the script, original illustrations were developed and characters were created. Page formatting, layout, and design were executed using Adobe Photoshop® and Adobe InDesign®, in collaboration with an experienced graphic designer. Content development followed key criteria related to substance, structure and organization, language, layout, design, cultural sensitivity, and contextual appropriateness for the intended audience. The characters were modeled after those used in previous publications from the Playing and Learning About Health project. To ensure clarity and accessibility, inclusive and respectful language was used to facilitate understanding and emphasize the roles of both individuals and families in promoting healthy eating practices.^{(Reference Alexandre and Coluci46)} During this phase, the Flesch Readability Index (FI) was calculated to ensure a minimum threshold of 70%, and classified the material as reasonably easy to very easy to understand.^{(Reference Benevides, Coutinho and Pascoal24,Reference Alexandre and Coluci46)}

1. 3 – Validation of the initial version:

Expert judges were provided with a printed copy of the comic book along with a questionnaire containing eight items to gather sociodemographic data. After a careful and critical reading of the material, they completed an evaluation questionnaire,^{(Reference da Rosa, Girardon-Perlini, Gamboa, Nietsche, Beuter and Dalmolin47)} which was organized into three sections: adequacy (5 items), structure (8 items), and relevance (5 items) of the comic book. Responses were recorded using a four-point Likert scale: Totally Adequate (TA), Adequate (A), Partially Adequate (PA), and Inadequate (I). Space was provided for the judges to justify their ratings and offer suggestions for improvement.

Based on the judges’ responses, the Content Validity Index (CVI) was calculated for each item (I-CVI), for each block (S-CVI/AVE Block), and globally (S-CVI/AVE Global). The CVI measures the relevance and representativeness of each element in a research instrument, with values ranging from 0 to 1. The calculation involved summing the number of responses rated as “Adequate” and “Totally Adequate,” dividing by the total number of responses, and multiplying by 100. The minimum acceptable threshold defined for this study was 80%.^{(Reference de Medeiros, Zanin, Sperandio, de Souza Fonseca Silva and Flório25,Reference Flório, Rached, Victorelli, Silva and Arsati26,Reference Benevides, Coutinho and Pascoal48)}

1. 4 – Preparation of the revised version of the comic book and pilot test:

Following the revisions to the comic book based on the expert judges’ suggestions, the FI was recalculated, and the final version of the material was completed. A pilot test was then conducted with representatives of the target audience. Before reading the comic book, participants completed a questionnaire comprising four sociodemographic questions and six questions assessing knowledge of practices related to healthy eating. This questionnaire – developed by the researchers and reviewed by 11 pediatricians and nutritionists – addressed the following topics: characteristics of a healthy diet^{(Reference Blumfield, Mayr and De Vlieger49,Reference Vinitchagoon, Hennessy and Zhang50)} ; recommendations for exclusive breastfeeding^{(Reference Meek and Noble51,Reference Nigatu, Azage and Motbainor52)} ; strategies for introducing complementary feeding^{(Reference Chiang, Hamner, Li and Perrine53,Reference Roe, Meengs, Birch and Rolls54)} ; characteristics of healthy snacks for children^{(Reference Jansen, Thapaliya, Beauchemin, D’Sa, Deoni and Carnell55)}; eating behaviors in children over 2 years of age^{(Reference Beets, Tilley, Kim and Webster56)}; and appropriate snack choices during the school year.^{(Reference Beets, Tilley, Kim and Webster56)}

The printed comic books were distributed, and after being made available for 15 days, participants completed an evaluation questionnaire regarding the material. The questionnaire was divided into 4 blocks: reading process (3 questions), content (6 questions), visual (5 questions), and characters (3 questions), using a valuation scale from “Totally Adequate” (TA) to “Inadequate” (I). Additionally, five questions addressed the organization, writing style, appearance, narrative motivation, and overall usefulness of the comic book.^{(Reference de Medeiros, Zanin, Sperandio, de Souza Fonseca Silva and Flório25,Reference Flório, Rached, Victorelli, Silva and Arsati26)} At this time, the knowledge questionnaire was also reapplied. The CVI for version 2 of the material was calculated at the item level (I-CVI), block level (S-CVI/AVE Block), and globally (S-CVI/UA Global).

The educational comic book developed and validated in this study is entitled Dentitos – Playing and Learning About Health: Food Health. On the inside cover, the Playing and Learning About Health initiative is introduced, along with its objective of using educational technologies to reach the target audience. The body of the publication consists of a comic strip, while the final section presents a timeline highlighting the key recommendations for food health in children aged 0 to 5 years, as well as thematic activities. The material was registered with the Brazilian Book Chamber (CBL) under ISBN: 978-65-86718-61-4 (Portuguese and English versions) and comprises a cover, back cover, and 16 pages, formatted in a standard size of 21 cm high by 14.8 cm wide. The final version of the comic book is available for free download in both Portuguese and EnglishFootnote ¹ .

For each version of the comic book, an exploratory statistical analysis was conducted using Microsoft Office Word, assessing components of the material, including the presentation and body of the comic strip. The number of pages, words, characters (with and without spaces), paragraphs, and lines – typed using single spacing – were recorded. Descriptive and exploratory analyses were also performed to characterize the profiles of the expert judges and members of the target audience, based on absolute and relative frequencies.

The FI was calculated for both versions (01 and 02) to evaluate the readability level of the text, based on a scale from 0 to 100. Higher FI values indicate easier reading and suggest that the material requires a lower level of formal education for comprehension by a lay audience.^{(Reference Benevides, Coutinho and Pascoal24)} CVIs were then estimated at the item level (I-CVI) for each block of the evaluation questionnaire completed by expert judges (objectives, structure, and relevance) and by the target audience (content, audiovisual elements, and characters). The CVI quantifies the proportion of evaluators who consider each item relevant or representative.^{(Reference Alexandre and Coluci46)} For this purpose, responses were grouped into two categories: “relevant/representative” (sum of responses rated “Totally Adequate” and “Adequate”) and “needs correction” (sum of responses rated “Partially Adequate” and “Inadequate”). Subsequently, CVIs were calculated at the block level (S-CVI/AVE), representing the average of the I-CVIs within each block, as well as the global level.

CVIs were also estimated at the scale level (S-CVI/UA), which measures the proportion of items rated as positive by each judge or layperson, along with the global average. In the present study, a minimum CVI of 0.70 (70%) was considered acceptable,^{(Reference Lopes, Silva and de Araujo57)} while a more stringent threshold of 80% was established to ensure the validity of the material.^{(Reference Benevides, Coutinho and Pascoal24–Reference Flório, Rached, Victorelli, Silva and Arsati26,Reference Yusoff58)} To compare scores on the knowledge questions before and after reading the comic book, the paired Wilcoxon test was applied. In addition, the absolute and relative frequencies of participants were calculated based on the change in the total score following the intervention. All analyses were conducted using R software, with the significance level set at 5%.