Happy Family Kitchen II: a cluster randomized controlled trial of a community-based positive psychology family intervention for subjective happiness and health-related quality of life in Hong Kong

Families residing in urban areas often face incompatible demands between work and family responsibilities, which can interfere with family communication and gatherings that are essential to the well-being of family members [1–3]. Therefore, a series of intervention studies under the umbrella of the FAMILY Project, including Happy Family Kitchen (HFK I) and Happy Family Kitchen II (HFK II), have been conducted to develop, implement, and evaluate a community-based positive psychology family intervention for improving family communication and family well-being in Hong Kong. These interventions were developed for families on the basis of positive psychology concepts applied to a cooking and dining setting. Based on use of a longitudinal methodology, results from HFK I provided initial support for the intervention program in improving family communication and family well-being [4]. Data derived from a cluster randomized controlled trial (cRCT) in HFK II provided further support with greater improvements in family health and family happiness in the intervention group than in the control group [5]. Extending our previous work, in the present paper we report findings on the individual-level outcomes of HFK II to examine the effectiveness of a positive psychology family intervention on subjective happiness and mental and physical quality of life.

Research done in the West has consistently provided evidence for the effectiveness of positive psychology interventions in terms of subjective well-being, such as life satisfaction, resilience, hope, and positive affect, and in reducing negative affect and pessimism [6–9]. Furthermore, the positive effect of positive psychology interventions extends to mental health: depressive symptoms have been alleviated in patients with depression as well as in individuals in the general population [9–12]. These interventions have typically involved some form of individual-based exercises to improve individual-level outcomes. The exercises can include imagining the best overall possible future (optimism), recalling positive events for which one is thankful (gratitude), and writing about the happy moments of life (joy) [13]. Family relationships are highly valued in the Chinese collectivist culture. In particular, family goals such as maintaining harmonious family relationships are valued over individual desires [14]. Family contact, quality, and functioning are important for the subjective well-being of the Chinese [15–17]. As we have previously reported the salutary effects of positive psychology family interventions on family well-being [5], a major contribution of the present paper is to evaluate the effect on individual-level outcomes, including subjective happiness as a measure of subjective well-being and the mental and physical components of health-related quality of life. To our knowledge, no similar studies have used a large-scale cRCT to examine the effectiveness of a community-based positive psychology family intervention on subjective happiness and mental and physical quality of life.

Although there is an abundance of positive psychology research from the West on subjective well-being and, to a lesser extent, mental health, very few of these studies have specifically examined physical health as an intervention outcome. A positive emotion regulation intervention was able to enhance not only subjective well-being and mental health but also physical health, such as reduced headache, stomachache, sleep problems, and cramps [18]. Another study showed that writing about positive experiences reduced the number of clinic visits for illness [19]. A comprehensive review of the literature found that the effectiveness of interventions designed to enhance physical health among ill populations through positive cognitions and attitudes, such as optimism and gratitude, was encouraging though not definitive [13]. Only one relevant study with a Chinese sample showed that a positive psychology stress management training program was effective for improving both psychological and physical symptoms of organizational stress in Hong Kong [20]. Although there has been minimal study of positive psychology interventions for promoting physical health, related psychosocial interventions have provided evidence for improving physical functioning and the immune system and for alleviating the symptoms of chronic illnesses [21–23]. Furthermore, a meta-analysis of findings derived from 150 experimental, ambulatory, and longitudinal studies demonstrated that subjective well-being has a positive effect on physical health, including short-term outcomes (e.g., immune system response and pain tolerance), long-term outcomes (e.g., cardiovascular functioning and respiratory functioning), and disease and symptom control (e.g., respiratory control and disease progression) [24]. Therefore, physical health might be one of the life domains that can be influenced by interventions aimed at promoting subjective well-being. Taken together, the evidence suggests that our intervention might be effective for enhancing the physical quality of life, even though it is psychosocially oriented.

In the design of the intervention, feasibility, practicality, acceptability, and sustainability were taken into consideration. Because the intervention was applied to a community setting, cooking and dining were chosen to provide a platform for family-based activities so that the intervention was feasible even for people with busy working lives. This was the most practical in Hong Kong because it is common for Chinese people to cook and dine with family members [25, 26]. To enhance the intervention’s acceptability to busy families, it was brief, with only one core session and one booster session, thus minimizing the burden placed on the service recipients and maximizing the retention rate. For sustainability, the brief nature of the intervention minimized program implementation costs, and the use of community venues, including social service units and schools, ensured that a large scope of community beneficiaries could be covered. To date, these intervention attributes are uncommon in the literature.

To foster positive communication among families in Hong Kong, five positive psychology themes, namely joy, gratitude, flow, savoring, and listening, were chosen for the intervention framework [5]. The “joy” theme was focused on discovering the short-term pleasures and long-term gratifications of positive family interactions [27]. The intervention involved sharing and reminiscing about happy experiences with family members and creating more enjoyable moments by cooking and dining together. The “gratitude” theme emphasized the importance of thanking and appreciating family members for their contribution and support [28]. The participants were encouraged to appreciate and express gratitude to their family members for contributing to family meals and other household chores. The aim of the “flow” theme was to engage family members in engrossing and enjoyable activities that could facilitate interaction, cooperation, and the identification of character strengths [29, 30]. Specifically, the participants were encouraged to prepare a family meal together, to stay focused during the activity, and to observe and identify each other’s strengths, such as curiosity, generosity, and teamwork. The “savoring” theme emphasized the importance of cherishing the enjoyable moments of family gatherings [11]. In particular, slowing down the pace of eating, savoring the food prepared by family members, and treasuring the good times during family meals were encouraged. The “listening” theme involved understanding and addressing the emotional needs of family members [30]. Participants were encouraged to actively listen to their family members when they spoke, to observe their nonverbal expressions, and to show interest in and acceptance of their emotions and concerns.

cRCT was adopted in the present study to examine the effects of a positive psychology family intervention on subjective happiness and mental and physical quality of life. The rationale for using a cluster design included the community-based nature of the intervention, the reduced risk of experimental contamination, and the efficacy of participant recruitment. The Consolidated Standards of Reporting Trials (CONSORT) cluster trials checklist shows this in more detail (Additional file 1). It was hypothesized that, at the individual participant level, participants in the intervention arm would show improvements in subjective happiness and mental and physical quality of life compared with the tea gathering control group (hypothesis 1 [H1]), as measured over time at baseline and at 4 weeks and 12 weeks postintervention, and that, after the core session, the booster intervention arm would show more improvements than the no-booster intervention arm in subjective happiness and mental and physical quality of life at 12 weeks postintervention (hypothesis 2 [H2]).