In a large representative sample of general population in Hong Kong Chinese, we found that low FS, presence of depressive symptoms (PHQ-9≥10) and presence of life stress were associated with unfavorable HRQoL, with the exception of FS having no association with physical HRQoL. We also found a significant interaction between sex-depressive symptoms and sex-FS for mental HRQoL. In contrast, only the sex-depressive symptoms interaction was significant for physical HRQoL. Regarding our third hypothesis, our study demonstrates that the interaction between FS and depressive symptoms was not significantly associated with physical and mental HRQoL. Nonetheless, among those with depressive symptoms (PHQ9≥10), high FS was associated with a favorable mental HRQoL in women but not men.
Both physical and mental HRQoL shared three common risk factors of depressive symptoms, life stress and older age, which is consistent with prior studies 
, . Researchers have proposed that social support may buffer against the negative effects of stress on individuals’ well-being 
. Associations of better FS with lower likelihood of reporting depressive symptoms 
and with favorable HRQoL have also been reported in previous studies 
. Nonetheless, our results have added to the understanding of the protective role of FS among people with depressive symptoms in a large group of community-dwelling individuals. We have also found that men are more likely to be affected by depressive symptoms than women as evidenced by the lower mental HRQoL. However, FS did not moderate the effect of depressive symptoms on mental HRQoL in men. Social support can be manifested at various levels and in this study, which has been measured at both the family and neighborhood levels, using FS and perceived neighborhood cohesion, respectively. FS, when compared to neighborhood cohesion, showed a stronger positive association with both physical and mental HRQoL. However, there are other sources of support which have not been included in this study, such as workplace and organization engagement, which may differentially affect HRQoL in men and women. Further studies are needed to explore how family, neighborhood, and other sources of support are linked to HRQoL among Chinese men and women.
Our study has addressed a vulnerable group in the community, namely, individuals with moderate or above depressive symptoms and lack FS are particularly prone to report low mental HRQoL. It would be worthwhile for primary care professionals or social workers to include a brief assessment of family function and support in routine consultations. For health promotion, enhancing family relationships could be an important primary prevention strategy to improve mental HRQoL in general and in high risk populations.
Experimental studies have demonstrated that physical activity could divert negative thoughts and elevate mood by enhancing secretion of endorphins 
. Epidemiological studies have also reported notable associations between negative emotions, heavier body weight and physical inactivity 
. In line with previous studies, we found that physical activity showed a medium to strong positive association with physical (β
0.50) and mental HRQoL (β
0.24). Most of the unhealthy behavioural factors including high-risk drinking and inadequate physical activity were significantly associated with unfavourable HRQoL. These suggest that healthy lifestyle promotion may be recommended as one of the means to maintain well-being in Chinese societies.
The present study has three strengths. First, a large sample of households and individuals were randomly selected from all 18 districts in Hong Kong, which produced a representative sample of the general population. Second, this study has examined the effect of sex-depressive symptoms interaction and sex-FS interaction in relation to HRQoL in a community-dwelling population. Third, the study focused on examining the potential protective role of FS in a culture that emphasizes the importance of family ties. Given many cultural similarities shared between Hong Kong and other rapidly modernizing urban areas in China and other Asian nations, our Hong Kong results may be applicable across Asia. The present study has a number of limitations. First, the method of including only complete households in our sample lowered the response rate and could lead to a self-selection bias towards families with more satisfying relationships. To look for such a potential bias, we drew a subsample of households that did not achieve complete enrolment of every member and randomly selected one member from each such household to complete the survey (N
1,930). A comparison analysis showed that the physical and mental HRQoL scores of these individuals did not differ to any substantial degree (Cohen’s d effect size <0.2) from the present study sample. Moreover, we did not find significant differences in FS comparing the complete households and incomplete households (mean of family APGAR 6.5 vs. 7.0, effect size
0.145). Second, without access to medical records and biomarkers, we could not adequately assess the severity of the chronic conditions and the impact of disease control on HRQoL. The interpretation of our findings is limited by the cross-sectional design; however the second wave of the FAMILY project is due to be completed by May 2013. The prospective data will enable us to examine the interplay between depressive symptoms, perceived FS and lifestyle factors and to test whether baseline depressive symptoms and FS predict future HRQoL.
Family support and presence of depressive symptoms was significantly associated with HRQoL in a representative sample of the general population in Hong Kong. Among participants with depressive symptoms, high family support also showed a significant protective role against deterioration in mental HRQoL for women but not men. For primary care professionals and social workers, family support assessment may be worthwhile in individuals with depressive symptoms.