Background: Convenient and quality family communication improves family functioning and well-being. Using mobile instant messaging (IM) for family communication is increasingly popular, but its association with family functioning and family well-being has not been reported. Objective: The aim of this study was to examine the association of the use of family IM chat groups with family functioning and well-being, and the mediating effect of family communication quality among Chinese adults in Hong Kong. Methods: We analyzed data from the Family and Health Information Trend Survey (FHInTS), a territory-wide, probability-based telephone survey conducted in 2017. The quality of family communication, family functioning, and well-being was assessed using the Family Communication Scale; Family Adaptation, Partnership, Growth, Affection, and Resolve (APGAR) Scale; and Family Well-Being Scale (family heath, harmony, and happiness), respectively. Respondents also reported the number of family IM chat groups (0, 1, 2, >= 3), and numbers of IM messages received (<1, 1-2, 3-10, 11-20, >20) and sent (<1, 1-2, 3-10, 11-20, >20) daily. The frequency of family IM chat interaction (range 0-8) was calculated by combining the number of messages received from and sent to the family IM chat groups daily. Covariates included sociodemographic characteristics and the frequency of family face-to-face communication (often, sometimes, seldom, or never). Data were weighted by sex, age, and education of the general population. Adjusted beta coefficients of family functioning and well-being in relation to having a family IM chat group, and numbers of messages received and sent were calculated. The mediation effects of family communication on these associations were assessed, controlling for the covariates. Results: A random sample of 1638 Chinese adults (45.6% men; 78.1% aged 25 to 64 years) were interviewed (response rate: 74.4%). Female, younger age, being married or cohabiting, higher education, higher income, better family functioning, and well-being were associated with having at least one family IM chat group (all P<.01). Higher scores of family communication, family APGAR, and family well-being were associated with having more family IM chat groups and more messages received from and sent to family IM chat groups daily (all P for trend <.01). More frequent family IM chat interaction was associated with higher scores of family communication, family APGAR, and family well-being (beta=.16-.83, all P for trend <.001). The associations of family IM chat interaction with family functioning and well-being were moderately (51.0%-59.6%) mediated by family communication. Conclusions: Use of a family IM chat group was associated with higher family functioning and well-being, and the association was partially mediated by family communication.
