The effect of social relationships on survival in elderly residents of a Southern European community: a cohort study

The protective effect of social relationships on the mortality of the elderly population has been shown in research using general social network indexes [1–6] or variables related to specific aspects of social relationships [7–22]. Differences among studies in the strength of the associations reported have been related mainly to variations in measurement and analysis strategies. Nevertheless, cultural variability may also explain differences in the associations between social networks and mortality, as shown in a study of three communities in the USA [3]. Research on social relationships and mortality in the Mediterranean region is scant, and most results on this topic are derived from studies conducted in Northern Europe, North America, and East Asia. Studies conducted in different cultures allow for increased variability in the nature and intensity of social contacts which could reveal effects not previously described.

Gender differences in the associations between social relationships and mortality may be culturally dependent, as reflected in conflicting results reported from Finland [8] and other countries [6, 15, 17, 19], and in differential effects observed in three American communities [3]. Socialization depends on gender, and its differential value can translate into dissimilar health effects.

Berkman & Glass [23] have reviewed cumulative evidence on the effect of social networks and support on health and incorporated it into their work. They propose a 'cascade' by which communities' socio-economic and cultural characteristics determine the structural characteristics of social relationships (the social networks). This structure supports functional aspects (psychosocial mechanisms, which include social support) that, in turn, influence health via psychological and physiological pathways. Testing of this model within different cultures is warranted.

The model proposes that social support mediates the effects of social networks. Most work on social support has centred on emotional and instrumental support received by older persons. More pro-active aspects like help provided by the older individual to others and the role he/she plays in their lives have rarely been considered [15, 20, 21]. Our aim is to test and expand the elements of the Berkman & Glass model among older Mediterranean men and women, including psychosocial aspects related to the social integration of older men and women in the most intimate social circles, comprised of family and friends, as well as their social involvement in their communities.

More specifically, the objectives of this paper are to analyse the influence on survival of social relationships among older men and women and to examine specific psychosocial mechanisms that may explain the effects of social networks on mortality in a Southern European community.

The study sample was taken from the first wave (1993) of the cohort study 'Aging in Leganés', whose main purpose was to describe changes in health status, disability and use of services among the community-dwelling elderly, and to relate such changes to social networks and support [24]. Leganés is a town of 173,584 inhabitants in the Madrid (Spain) metropolitan area. A random sample of 1,560 individuals aged 65 years or older was obtained from the municipal roll, stratified by sex and two-year age groups (65–66, 67–68, ...89 or over). Data were collected during two home interviews. During the first visit, trained interviewers asked questions on socioeconomic aspects, health status, Activities of Daily Living (ADLs) and Instrumental Activities of Daily Living (IADLs) disability, depressive symptoms, use of health and social services, and social relationships. During the second visit, physicians inquired about mobility, lifestyle, weight, accidents, vision and hearing ability, and incontinence, and performed a partial physical exam (blood pressure, height, cognitive function, visual acuity, audiometry and mouth inspection). When an individual was unable to answer due to cognitive deficit (Pfeiffer's Short Portable Mental Status Questionnaire score 5 or higher [25]), severe hearing problems, severe illness or aphasia, the interviewer requested the assistance of a proxy respondent to reply to questions unrelated to personal feelings.

Of the 1,560 eligible subjects in the sample, 1,283 (82.2%) answered the questionnaire, while 152 (9.7%) refused participation, 120 (7.7%) were absent from home on three occasions and 5 (0.3%) were hospitalized. Of those who answered, 93% underwent the medical exam. Their age, sex, marital status, education and self-perceived health distributions were similar to those of the 1987 Spanish National Health Survey. In 105 cases, information was provided by a proxy due to the subject's cognitive impairment (83.8%), speech or hearing problems (45.2%), severe physical illness (24.2%) or unspecified causes (6.6%). It was possible to register more than one condition for each case. Three individuals did not provide any information on social relationships, and in two cases vital status was not known. This left a final study sample of 1,174 individuals.

In the over 6-year follow-up period, 352 of the 1,174 baseline participants died (30%; 95% CI 27.4–32.7). This rate was lower than that of the 386 eligible subjects not included in the analysis (42.2%; 95% CI 37.3–47.2). Non-response at baseline was higher among women and the very old.

Gender differences were observed with respect to most variables: women were older, less educated, in worse health, with more depressive symptoms and more disability. Women exercised less than men, they lived alone more often, were more frequently widowed, and their family ties index was lower. In addition, their social participation activities were less diversified. Women contacted friends less frequently, and their appraisal of their role in the lives of their significant others was lower as compared to men. Having a confidant was as frequent among men as among women.

Bivariate analyses showed a significant association between a higher level of social relationships and survival (data not shown). Only two variables, receipt of emotional support (in both sexes) and contacts with friends were not statistically associated with survival. Potential confounders were related to mortality in the expected direction except for co-morbidity (in women).

The family ties index was dichotomised because there were too few individuals with one or no family ties to allow for estimation of coefficients in these categories. These individuals were merged with those having an average of two monthly contacts. Redefined in this fashion, this variable was very significant for men, and its effect was partially explained by health and disability variables.

Contacts with friends had no effect on survival. Diversified social participation had a protective effect, and showed a similar gradient for men and women. However, the association lost significance when all health and disability variables were included in the model. Figure 1 displays the probability of being alive at each follow-up year for each more activity the individuals took part in, after adjustment for sociodemographic and other social relationships variables (when health and disability variables were included, the gradient was partially lost, with the hazard ratio for those performing one activity closely approaching that of persons who performed no activities). After adjusting for socio-demographic, other social relationships and health and disability variables, the risk of death of an individual who did not participate in any of the activities was 1.5 times (95% CI 1.3–1.7) the risk of a full participant.

Having a confidant showed a greater protective effect in men, but sex differences disappeared when health and disability variables were included. When men and women were combined, the relationship was significant even with all variables in the model: having a confidant is associated with a 25% (95% CI 5–40%) reduction in the mortality risk

Receipt of emotional support was not associated with mortality. An increasing role of the individual in the lives of significant others showed a protective effect in both sexes, which reached statistical significance only in the combined model. The significance was lost after adjusting for health and disability. Again, no evidence against a gradient of the variable effect was found.

Four components of social relationships are associated with 6-year survival in this elderly Southern European population: contacts with family ties, participation in social activities, having a confidant, and playing a meaningful role in the lives of significant others. Contacts with family ties and having a confidant remain significantly associated with improved survival, whereas participation in social activities and meaningful role in the lives of significant others lose significance after adjustment for health and disability variables. This suggests that the effects of social relationships on survival may be partly mediated by the fostering of better health and function.

This population enjoys relatively high levels of social contact, centred on family life, as would be expected in a Mediterranean community. Nevertheless, these levels are not as high for women as for men. A National Survey has confirmed this finding, reporting fewer contacts with friends and relatives among Spanish women [39]. Women in our cohort show worse family ties indexes mainly because they are older and, consequently, more frequently widowed. In addition, they have fewer contacts with friends and less participation in social life. This last result is congruent with findings in Finland [8] and Taiwan [19], but dissimilar to those in France [6] and Denmark [15] (where there are no differences between sexes) and the USA [11] (where women enjoy a larger social network and more social participation). Our tentative explanation for these differences is that women in our cohort have lived most of their lives in a cultural background that favoured their engagement in family life over their participation in activities outside home. We can hypothesize also that the still predominant patriarchal way of thinking in the Mediterranean culture has driven downward these women's self-perception of their capacity of helping and influencing others' lives.

Our analyses show similar protective associations between social relationships and mortality for both sexes (apart from that of the family ties index), so the more limited social relationships women enjoy make them less able to benefit from them. Nevertheless, it is worth mentioning that one of the variables most strongly associated with survival – having a confidant – is equally distributed among men and women. Differences by sex in the association between community participation and survival in the elderly were not observed in another European community [8], but they were present in a Taiwanese one [19]. A USA study that included elderly and young individuals and used a general index of social integration described differential effects between the sexes [3]. It is hard to say whether or not these conflicting results can be attributed to the use of differential scales or to real geographical-cultural effects.

Men with the highest diversity of family ties enjoy better survival. Out of the 163 men with fewer than three family ties, 128 were widowers, while only 36 had no children and 30 had no close relatives. Moreover, when this variable was replaced in the model by marital status (data not shown), the protective effect of being married was very similar to that of the dichotomised family ties index. Therefore, what our dichotomised index is measuring is probably the beneficial effect of being married for men, a finding well reported in the literature on the elderly [6, 7].

Community activities (social participation) have generally been reported as predictors of survival [2, 8–10, 18], although there is conflicting evidence from Sweden [40]. This is not due to higher physical and functional levels of those who participate in them, because, in our study and others, adjustment for health and function does not change the magnitude of the association of community participation with mortality. Moreover, the same effects have been reported in elderly people with different levels of physical activity [41]. In the seminal Tecumseh study [42], leisure activities that did not include social contact (reading, watching TV) did not confer the protective effect generated by social activities, which rules out attributing the beneficial associations observed to entertainment alone. Qualitative research in Spain [43] sheds some light on the positive effects of community activities on mortality: For elderly people, participation in these activities is a way to maintain full participation in society and show that being old does not equal being useless, passive and dependent. In addition, social activities provide room for personal contacts and a daily routine that is a substitute for productive and reproductive work.

Having a confidant appears to be a very strong predictor of survival. It is somewhat surprising that this feature has not been thoroughly investigated in previous studies dealing with mortality. We are aware of only two pieces of research [22, 44] which included this variable: no effect was observed in the last one, although its small sample size may have limited power. On the contrary, the Australian cohort study found significant protective effects for having a confidant. The mechanisms through which having this kind of support influence survival are included in the formulation of the question we used to explore this topic. Our item defined a confidant as someone whom the subject can talk to, confide in and trust. Therefore, it behaves as a summary measure of various health-related psychosocial mechanisms. Apart from this increase in overall survival, confidant availability has been reported to reduce the risk of cardiac events after infarction [45], cardiovascular death in patients with ischemic disease [46] and depressive symptomatology incidence among the elderly [47].

The Australian study [22] and others [14, 19] have found that having and contacting friends postpones death. Our results show this not to be the case in a Mediterranean community where, probably, family ties are more highly regarded. Family ties appear to be more important for survival, as shown by the protective effect of the family ties index in men, and the fact that, in our cohort, 90% of women's and 98% of men's confidants were members of their families.

Of the other two psychosocial mechanisms considered, receipt of social support and playing an important role in the lives of significant others, only the latter is protective. A study in Japan found that a sense of "present usefulness to others and society" in elderly participants was predictive of longer survival even after adjusting for self-rated health [21]. However, the sense of usefulness was evaluated with a single question, whereas we used a scale, a procedure more suitable for measuring elaborated constructs. Conceptually related variables, such as the ability to take care of others among functionally impaired elderly persons [15] or the emotional and instrumental support given to the spouse among the community dwelling elderly [20] have shown some beneficial effects. Ostir, Simonsick, Kasper & Guralnik [48] measured the rate of satisfaction of elderly disabled women with respect to the help they provided to family, friends and community organizations. They found that higher levels were associated protectively with better lower-body function as well as less ADL difficulty, hospitalisation and mortality, even after adjusting for socio-demographic, medical conditions and baseline disability variables. The finding that survival is associated with what is given by the individual (his/her role) and not with what is received (emotional support) can be attributed to the fact that in the first case the subject plays an active role that can provide purpose or meaning to life and helps him/her remain mentally and physically active. In a recent study, feelings of worth and emotional support were also associated with survival in very elderly women [49].

This paper provides limited information on the pathways through which social networks generate their effects. The introduction of psychosocial mechanisms does not give rise to a major change in the association between mortality and social network variables; therefore the structural components of social relationships generate an effect on health that is not fully explained by the functions considered in the model – a result at odds with the scheme proposed by Berkman & Glass.

The question remains as to the extent to which our results can be applied to other populations. The elderly of Leganés have generally moved to Madrid from various central regions of Spain, and their age, sex, marital status, education and self-perceived health distributions represent that of elderly Spaniards as a whole. Nevertheless, cultural differences among the Spanish regions exist, although in all of them, as in other Southern European communities, family plays a central role in the social networks of the older population. Our results are based on a Mediterranean community. Since social relationship patterns are culturally dependent, it would be necessary to test our findings on the effects of roles and confidants in other populations.

The evidence provided by numerous observational studies on the protective effects of social relationships on mortality is solid enough to develop and evaluate interventions which promote social networks and support of the elderly population. Nevertheless, interventions should not be directed only at the individual level. As Berkman & Glass reflect in their conceptual scheme, social relationships are determined by sociodemographic, cultural and political forces. Positive effects on survival and quality of life may be produced by public policies that regulate labour markets and taxation; allow for conciliation of work and care of family members; promote the acquisition of larger dwellings or dwellings closer to the family's usual place of residence; facilitate access to home care for the elderly who wish to stay at home as long as possible; and empower civil society so that spaces for community intergenerational interaction can flourish.