The mental health burden is increasing worldwide, posing several challenges to low-to-middle income countries such as Brazil. The World Health Organization (WHO) estimates that more than 300 million people have depression worldwide, and less than half have access to treatment (1).

Depression is currently the most significant cause of absenteeism and disability in the workforce (2) and the second largest cause of disability worldwide.

The incidence of depression has increased by 59.8% from 1990 to 2017, and is the most common chronic disease worldwide, at present (3). Depression treatment costed approximately US$ 236 billion in 2018 in USA, an increase of more than 35% since 2010 (4). According to recent data, at least 14% of the Brazilian population suffers from depressive symptoms, while 17% have had an episode of major depression throughout their lives (5).

The WHO defines health as “a state of complete physical, mental and social wellbeing and not only the absence of disease” (6). However, this definition does not consider the dynamic nature of human beings. Therefore, new concepts are emerging in literature. We would like to highlight a specific one called flourishing, coined by Tyler VanderWeele, which defines health as “the state in which all aspects of a person's life are good” (7). According to this concept, there are five broad domains of human life: (i) happiness and life satisfaction; (ii) health, both mental and physical; (iii) meaning and purpose; (iv) character and virtue; and (v) close social relationships and four pathways, i.e., family, work, education, and religious community (8).

Previous longitudinal studies with large samples have already shown promising effects of VanderWeele's flourishing dimensions/pathways on physical and mental health. A US national cohort with ~13,000 adults aged >50 years has shown that individuals with greater purpose of life had lower mortality risk (9) and that altruistic behaviors (e.g., volunteering) were associated with lower mortality, and better physical activity and psychosocial outcomes (10). On similar lines, a US cohort with ~60,000 nurses found that forgiveness was associated with higher levels of positive affect and social integration and lower levels of psychological distress (11), and religious attendance was related to lower risk of death (12).

This longitudinal data supports that the broader concept of health has robust scientific evidence and should be discussed by the scientific literature. Within this context, several interventions based on human values and virtues were proposed, and publications on positive mental health programs (13, 14) showed promising results toward minimizing depressive symptoms in different populations (15–18). Although there are several clinical trials regarding the effectiveness of virtues, values, and character on health outcomes (19, 20), to the best of our knowledge, there is a scarcity of studies combining different aspects of flourishing, that focus on VanderWeele's concept (8). Since the concept of flourishing embraces different dimensions which are linked to better health outcomes, promoting all of these dimensions in a single intervention may have better results than considering them separately.

The purpose of this study was to advance this field of research by creating an intervention protocol combining different aspects of flourishing to deliver in a few group sessions. Therefore, this study aimed to develop a simple, practical, and low-cost intervention protocol to promote mental health based on the conceptual framework of flourishing, through an e-Delphi technique.

The study was approved by the Research Ethics Committee of the School of Medicine of the University of Sao Paulo, Brazil, under approval number CAAE: 52554221.4.0000.0068. All respondents provided written informed consent.

The study was organized into four phases, as shown in Supplementary Figure 1.

The present study successfully developed an intervention protocol based on the flourishing concept of health using a comprehensive literature review and the opinion of experts through the e-Delphi technique. The protocol consists of sharing therapeutic tools during online sessions in collaboration with trained healthcare professionals to conduct the sessions. Though there are other mental health programs focusing on positive aspects, but in this intervention, we specifically sough to adopt the VanderWeele's concept of flourishing and combine its various topics into the sessions offered (13, 14). This intervention is different from others because it combines all virtues and values in a single intervention, resulting in a more holistic and comprehensive approach.

For the development of this protocol, our study followed previous articles that used Delphi or e-Delphi to develop an intervention (21, 22, 69). Delphi is a technique that can impact ways of thinking or decision making through the convergence of opinions and comments of experts' assessments (21). The main advantage of using such a technique is the possibility of exploring underlying assumptions regarding a specific topic (69).

According to the literature, one of the most important aspects of Delphi is the choice of experts. Our experts were mostly from the field of mental health, and this choice was made considering the main outcome of our intervention (reducing depressive symptoms and promoting mental health) and the experience of the experts in the precepts of positive psychology. However, it is important to highlight that, to improve the public health feasibility of this protocol, professionals from other healthcare fields were also included. Another important choice for our panel selection was to include experienced PhD holders for the e-Delphi. This choice guaranteed that well-qualified experts with expertise in both clinical practice and research were included, which was supported by previous studies (21, 22).

An important choice in the development of our protocol was the use of an online e-Delphi technique, instead of a Delphi technique. The e-Delphi has some important advantages such as time and cost savings, convenience for experts and the research team, and data management facility (21, 22). The individualized communication with experts and their blindness regarding the other experts' answers during the process may have contributed to the impartiality of scores, ideas, and suggestions provided.

Regarding the protocol, the experts favored the online format of the interventions. The advantages of using this type of approach include the use of multimedia for the participants, facilitating access to complex content, time and cost savings, and the possibility of engaging with others (26, 27). The use of an online approach is supported by previous studies where clinical trials of brief online intervention programs showed better long-term clinical effects compared to face-to-face therapies for different mental health conditions, especially when the technique included the support of a healthcare professional (70).

As verified through the results, experts reached consensus for ~90% of the items, revealing that the intervention was consistent with the proposal of flourishing. However, it is important to highlight that one item was subjected to three rounds of e-Delphi to reach consensus: the objective of the spirituality session. To achieve the goal for this session the following concept mentioned by Puchalski (71) was adopted: “spirituality is the aspect of humanity that refers to the way individuals seek and express meaning and purpose and the way they experience their connectedness to the moment, to self, to others, to nature, and to the significant or sacred.” Some experts argued that spirituality should be related to the sacred or an immortal being and not to the connectedness to the moment, self, or others. Since our main goal in this session was to be inclusive, Puchalski's definition was chosen because it provides a more comprehensive understanding of this construct, in which individuals can recognize their beliefs and values, and identify which connections are meaningful to them, regardless of sacred or religious beliefs. Most experts highlighted the notions of transcendence and connection as relevant aspects to be addressed in this session. In the third round a consensus was reached and the session was renamed “Spirituality and Inner Connection.”

Another important highlight by the experts was the order of the topics of flourishing. The experts did not initially agree to address gratitude and imagining your “best future” in the same session, even though both topics could stimulate an individual to connect with the environment and with others. Comments included that the exercises proposed should be provided separately to achieve their personal goals, and that imagining a “better future” could be more useful at the end of the intervention to synthesize the concept of flourishing. The authors revisited the order of the topics maintaining the rationale initially proposed, to achieve an increase in complexity of the virtues and values of the process of flourishing (8).

Regarding the structure of the intervention, the experts agreed on the 12 weekly sessions; however, not all experts agreed with the duration of 90-min. Since online interventions have operational challenges, such as speed of connection and learning of operating the multimedia (70), a loss of therapeutic time should be considered. Also, group sessions including 10–15 participants need adequate time to allow everyone to express their ideas and opinions. Therefore, this program needs to be tested in clinical practice so that its viability can be confirmed. The experts were also consulted regarding the general use of the multimedia resources, slides for the sessions, and proposed items to include a variety of tools to ensure a better group dynamic, and most opinions were favorable.

Concerning the target population, people with mild and moderate depressive symptoms tend to respond well to most psychotherapy approaches, irrespective of whether those are self-help or cognitive-behavioral therapy (CBT) interventions (72–74). There are, however, reports of lower effects and high rates of treatment dropout when no human therapeutic support is offered, and the patient has only access to the content generated by the electronic platform (74, 75). There is clear evidence that the computer cannot fully replace human contact (76). Therefore, our intervention was developed as a synchronous online approach including full support of the healthcare professionals throughout the program for the participants, making it a relevant therapeutic alliance (73).

Finally, it is noteworthy that most studies investigating mood disorders and web-based treatments do not deal with major depression diagnoses, but with symptoms of depression (72, 77). Given the evidence found in the literature, our intervention was designed for individuals with depressive symptoms and not for those with a diagnosis of major depression. Most experts agreed that this intervention could be used for mild to moderate depressive symptoms, which is supported by the previous literature. Future studies using this protocol should explore which group of participants will benefit the most through this intervention.

The study has some limitations. First, the experts who evaluated the protocol were invited to participate through the authors' professional relationship network. Purposive sampling was used to recruit professionals to serve in the expert committee. However, experts were form different institutions, had different backgrounds, and experiences in the field. Second, the intervention was developed in Portuguese language. Although we had an English version translated by a professional native English speaker translator, no cross-cultural adaptation was carried out. This protocol should be tested in other languages and cultures to verify if the sessions are feasible and meaningful, aiming to make the flourishing intervention culturally sensitive.

The development of the flourishing intervention aims to fill the gap in public health approaches since it is a practical and low-cost intervention. Interventions in groups have an advantage of providing greater efficiency and cost-effectiveness to health services (78), besides the benefits to patients (79), as they facilitate the exchange of experiences and support by expanding the social support network.

Furthermore, the flourishing intervention aims to train healthcare professionals from different backgrounds and expertise, providing fundamental skills to conduct the intervention as a new healthcare tool. Investment in continuous education of multidisciplinary teams has proved to be a significant resource for implementing technical innovations, which aim to change practices in health systems and, consequently, in communities (80). The authors developed a guide for the providers on specific information for conducting the sessions, such as troubleshooting and managing therapeutic groups. The experts had access to this material and highlighted its relevance. The providers' guide is an accessible material for healthcare professionals to understand the exercises and tools proposed for the sessions. The intention is to allow this to be reproducible in different healthcare contexts. A study pointed out that it is important for professionals conducting online interventions to have clinical experience, empathy, and robust knowledge of the technique used, otherwise the intervention may have less effect (26). Therefore, adequate material and training are essential to ensure the best use and effectiveness of the intervention.

The development of the intervention based on the concept of flourishing obtained consensus from the experts. Necessary adjustments were made by the team, and the protocol reformulation proved to be successful. The intervention is ready to be tested in an experimental study to verify its feasibility and effectiveness.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The study was approved by the Research Ethics Committee of the School of Medicine of the University of Sao Paulo, Brazil, under approval number CAAE: 52554221.4.0000.0068. All respondents provided written informed consent. The patients/participants provided their written informed consent to participate in this study.

JG: conception and design of the work, data collection, data analysis and interpretation, drafting the article, and final approval of the version to be published. CB: data collection, data analysis and interpretation, drafting the article, and final approval of the version to be published. WA: data analysis and interpretation, critical revision of the article, and final approval of the version to be published. CG: data interpretation, critical revision of the article, and final approval of the version to be published. GL: conception and design of the work, data analysis and interpretation, critical revision of the article, and final approval of the version to be published. HV: conception and design of the work, data interpretation, critical revision of the article, and final approval of the version to be published. All authors contributed to the article and approved the submitted version.