Abstracts

Introduction

Over the last decades, the proportion of older adults has significantly increased in Chile and other Latin American countries because of the decrease in mortality and fertility rates and increased life expectancy. Between 1992 and 2020, the annual average growth of the population aged 60 years and older was 3.3%, three times higher than the 1% average growth of the population aged 0-59 years ¹1. Instituto Nacional de Estadísticas. Chile: ciudades, pueblos y aldeas. Censo 1992. Santiago: Instituto Nacional de Estadísticas; 1995.^,22. Comisión Económica para América Latina y el Caribe. CEPALSTAT. Bases de datos y publicaciones estadísticas. https://estadisticas.cepal.org/cepalstat/Portada.html (accessed on 10/Mar/2021).
https://estadisticas.cepal.org/cepalstat... . Currently, people aged ≥ 60 years represent 17.4% of the population (3.3 million) ²2. Comisión Económica para América Latina y el Caribe. CEPALSTAT. Bases de datos y publicaciones estadísticas. https://estadisticas.cepal.org/cepalstat/Portada.html (accessed on 10/Mar/2021).
https://estadisticas.cepal.org/cepalstat... . Chileans are likely enjoying longer lives because of health, social, and economic factors. Besides Costa Rica and Cuba, Chile is one of the countries with the highest life expectancy at birth and at age 60 in Latin America ²2. Comisión Económica para América Latina y el Caribe. CEPALSTAT. Bases de datos y publicaciones estadísticas. https://estadisticas.cepal.org/cepalstat/Portada.html (accessed on 10/Mar/2021).
https://estadisticas.cepal.org/cepalstat... .

In North America ³3. Berkman LF, Syme SL. Social networks, host resistance, and mortality: a nine-year follow-up study of Alameda County residents. Am J Epidemiol 2017; 185:1070-88., Europe ⁴4. Laugesen K, Baggesen LM, Schmidt SAJ, Glymour MM, Lasgaard M, Milstein A, et al. Social isolation and all-cause mortality: a population-based cohort study in Denmark. Sci Rep 2018; 8:4-11.^,55. Rodriguez-Laso A, Zunzunegui MV, Otero A. The effect of social relationships on survival in elderly residents of a Southern European community: a cohort study. BMC Geriatr 2007; 7:19., and Asia ⁶6. Gao M, Sa Z, Li Y, Zhang W, Tian D, Zhang S, et al. Does social participation reduce the risk of functional disability among older adults in China? A survival analysis using the 2005-2011 waves of the CLHLS data. BMC Geriatr 2018; 18:224., studies have documented the association between social participation and mortality for at least 40 years. Moreover, older adults have been studied on their degree of social relationships and social engagement regarding functional limitations ⁶6. Gao M, Sa Z, Li Y, Zhang W, Tian D, Zhang S, et al. Does social participation reduce the risk of functional disability among older adults in China? A survival analysis using the 2005-2011 waves of the CLHLS data. BMC Geriatr 2018; 18:224., mobility ⁷7. Buchman A, Boyle P, Wilson RS, Fleischman D, Leurgans S, Bennett DA. Association between late-life social activity and motor decline in older adults. Arch Intern Med 2009; 169:1139-46., cognitive impairment ⁸8. Berkman LF, Glass T, Brissette I, Seeman TE. From social integration to health: Durkheim in the new millennium. Soc Sci Med 2000; 51:843-57.^,99. Engelhardt H, Buber I, Skirbekk V, Prskawetz A. Social involvement, behavioural risks and cognitive functioning among older people. Ageing Soc 2010; 30:779-809., and dementia ¹⁰10. Wang H-X, Karp A, Winblad B, Fratiglioni L. Late-life engagement in social and leisure activities is associated with a decreased risk of dementia: a longitudinal study from the Kungsholmen project. Am J Epidemiol 2002; 155:1081-7.^,1111. Wilson RS, De Leon CFM, Bienias JL, Evans DA, Bennett DA. Personality and mortality in old age. J Gerontol B Psychol Sci Soc Sci 2004; 59:110-6.. However, the increasing proportion of the older population affected industrialized countries and is expected to virtually affect all countries ¹²12. Lee R, Mason A. Some macroeconomic aspects of global. Demography 2010; 47 Suppl 1:S151-72., promoting interest in the association between social participation and mortality in older adults ³3. Berkman LF, Syme SL. Social networks, host resistance, and mortality: a nine-year follow-up study of Alameda County residents. Am J Epidemiol 2017; 185:1070-88.^,1313. Minagawa Y, Saito Y. Active social participation and mortality risk among older people in Japan: results from a nationally representative sample. Res Aging 2015; 37:481-99.^,1414. Wu J, Li J. The impact of social participation on older people's death risk: an analysis from CLHLS. China Popul Dev Stud 2018; 2:173-85..

Studies show that maintaining an active social involvement is associated with lower mortality risk ¹³13. Minagawa Y, Saito Y. Active social participation and mortality risk among older people in Japan: results from a nationally representative sample. Res Aging 2015; 37:481-99.^,1414. Wu J, Li J. The impact of social participation on older people's death risk: an analysis from CLHLS. China Popul Dev Stud 2018; 2:173-85.^,1515. Ang S. Social participation and mortality among older adults in Singapore: does ethnicity explain gender differences? J Gerontol B Psychol Sci Soc Sci 2018; 73:1470-9.^,1616. Murata C, Kondo T, Hori Y, Miyao D, Tamakoshi K, Yatsuya H, et al. Effects of social relationships on mortality among the elderly in a Japanese rural area. J Epidemiol 2005; 15:78-84.^,1717. Sato T, Kishi R, Suzukawa A, Horikawa N, Saijo Y, Yoshioka E. Effects of social relationships on mortality of the elderly: how do the influences change with the passage of time? Arch Gerontol Geriatr 2008; 47:327-39.. Berkman & Syme ³3. Berkman LF, Syme SL. Social networks, host resistance, and mortality: a nine-year follow-up study of Alameda County residents. Am J Epidemiol 2017; 185:1070-88. studied four sources of social relationships (marriage, contact with family and close friends, church membership, and participation in formal or informal associations), finding that people who maintain social ties or relationships have lower mortality rates than those who do not. Minagawa & Saito ¹³13. Minagawa Y, Saito Y. Active social participation and mortality risk among older people in Japan: results from a nationally representative sample. Res Aging 2015; 37:481-99. found that, even with controlled sociodemographic, health status, and family relations variables, older people in Japan who participated in at least one social group had a 27% lower death rate than those who did not participate in any social group. Similarly, Wu & Li ¹⁴14. Wu J, Li J. The impact of social participation on older people's death risk: an analysis from CLHLS. China Popul Dev Stud 2018; 2:173-85. found that secular and religious social participation is related to lower risk of death among older people in China.

In Chile, older adults who participate in organizations are associated with higher subjective well-being ¹⁸18. Herrera MS, Elgueta RP, Fernández MB. Social capital, social participation and life satisfaction among Chilean older adults. Rev Saúde Pública 2014; 48:739-49., whereas older people who live alone have higher mortality rates than those who live with their partners, husbands, wives, and children ¹⁹19. Sandoval MH, Turra CM. El gradiente educativo en la mortalidad adulta en Chile. Revista Latinoamericana de Población 2015; 9:1-29.. However, analysis of the association between social participation and mortality rate in older adults in Latin America, particularly in Chile, is still incipient. This study therefore aimed to examine how social participation is associated with mortality risk in older adults in Chile. Considering the findings described for other societies, we expected to find a lower mortality risk among men and women who participate in social organizations.

Methods

Data

This study was based on data from the Chilean National Survey of Dependence in Older People (Estudio Nacional de la Dependencia en Adultos Mayores), a cross-sectional survey conducted from 2009 to 2010 in a probabilistic national representative sample of 4,766 people aged 60 years or older. From this sample, 160 individuals (3.3%) were excluded due to missing information in the variables of interest, totaling 4,606 analyzed older adults, among whom 708 died during follow-up. The survey data were linked with death records from the Civil Registration Service. The studied period corresponds to the application date of the survey (2009-2010) to April 7, 2015 (right-censored data).

Variables

During the 5-year studied period, the primary dependent variable was “risk of dying” and the main independent variable was “social participation”. The survey included the question: “Do you participate in any community group, club, or organization?” (Answer 1. Yes or 2. No). For research purposes, social participation is considered older adults who declared participating in at least one of the social organizations included in the questionnaire.

Demographic variables were considered as covariates, including: sex (men and women), age (60-69; 70-79; 80-89; and 90 or more years), and socioeconomic factors - schooling (0 to 6 years or 7 or more years), occupation (employed or not employed), and living arrangements (living with a partner, living alone, living with a partner and children, living alone with children, living with others). Five variables were included as health status: (1) self-perceived health (good or poor health); (2) number of chronic diseases; (3) limitation in activities of daily living (ADL); (4) limitation in instrumental activities of daily living (IADL); and (5) dependency. The survey asks if the participant has been diagnosed by a physician or nurse with any of the chronic diseases addressed in the study (hypertension, diabetes, heart disease, lung disease, embolism, thrombosis, ischemia or stroke, depression, cancer, arthritis or osteoarthritis). The variable “number of chronic diseases” was created by grouping the two possible answers (1. Yes; 2. No) to each disease into one of four categories: (a) none; (b) one disease; (c) two diseases; and (d) three or more diseases. Moreover, the variable “dependency” was grouped into three categories: no dependency, mild or moderate dependency (requires assistance to perform 1. ADL; or 2. IADL), and severe dependency (is bedridden or has dementia or cannot perform two or more ADLs and IADLs).

Analytical strategy

A series of Cox proportional hazards models were estimated to study the association between social participation and mortality risk in older adults. The model specification without interaction terms is as follows:

Note that, survival time corresponds to years of survival.

Four models were considered. The first model examines the main association of social participation with mortality in older adults. Demographic variables (sex and age) were added in the second model considering that levels of mortality and social participation vary between men and women and social participation is likely to be higher in younger older adults, mainly women. Socioeconomic (education and occupation) and family (living arrangement) variables were added in the third model considering that socioeconomic conditions and living arrangements of older adults influence their mortality and social participation levels. Finally, the fourth model considered covariates related to improved health status, which favors social participation and is associated with lower risk of mortality. The implementation of the proportional hazards was tested using the sphtest command in Stata software (https://www.stata.com). This command performs a global test and independent tests for each predictor. All four models in this study support the proportional hazards assumption. The software Stata 14 was used to estimate the models.

Results

Table 1 details the analyzed sample, showing that 70% of older adults do not participate in any social association, out of which most (61%) are women and were aged under 80 years when they entered the study. Most older adults had low schooling levels (69.6%), were unemployed (81.3%), and lived in other living arrangements (45.3%), whereas 18% lived with their partner, 16.5% lived alone, and the remaining 19.9% lived with their partner and adult children (10.7%) or only with their adult children (9.2%). More than 50% declared having poor health whereas 48.3% declared having two or more chronic diseases. However, most reported no difficulties in performing ADL or IADL. Finally, regarding dependency, 74% were independent, while 9.1% had a mild-moderate level of dependency and 16.8% had a severe level (Table 1).

Figure 1 shows differences in the survival curves according to social participation for older men, older women, and the total sample. Those who did not participate in social activities had higher mortality during the 5-year follow-up, including all older people, only men, and only women. However, these groups have different survival curves (p-value = 0). Women who participate in social organizations had lower mortality than men.

Table 2 contains the hazard ratio for each estimated model. Model 1, which measures the effect of social participation on mortality risk, shows that older people who participate in at least one social association have 52% lower mortality risk than those who do not participate in any. Model 2, which includes the demographic variables sex and age, shows a lower effect of social participation on increased survival. However, its protective effect is still significant, reaching 41%. As expected, mortality risk was higher in men, increasing with age.

In Model 3, the effect of social participation is statistically significant (p < 0.001) despite decreasing with socioeconomic and living arrangement variables. Another expected result is related to the inverse association between schooling rate and mortality in older age, considering that older adults with lower schooling levels had a 30% higher mortality risk than those with higher schooling levels. Older adults who declared they continue to work had a lower mortality risk. Lastly, adults who lived with their husbands, wives, or partners had lower mortality risk than those living in another kind of arrangement.

Model 4 includes the covariates associated with health condition, showing that older people who participate in social associations or organizations (politics, sports, religion, neighborhood, etc.) had a 22% lower mortality risk than those who do not participate in any social group. That is, social participation significantly affects lifespan (p < 0.05) despite controlled demographic, socioeconomic, living arrangement, and health variables. Health covariates behavior shows expected results: worse health conditions in all studied dimensions are associated with higher mortality risk.

According to the Akaike information criterion (AIC) and Bayesian information criterion (BIC), among all models, Model 4 fits the best (lower AIC and BIC values).

Discussion

We associated a representative sample of older adults with the official vital statistics of Chile, showing that participating in social associations or organizations is statistically correlated with lower mortality risk in old age. Older adults who mentioned participating in any association had a 22% lower mortality risk than those who did not participate in any, even with controlled demographic, socioeconomic, living arrangement, and health variables. Similar results have been described for industrialized countries ³3. Berkman LF, Syme SL. Social networks, host resistance, and mortality: a nine-year follow-up study of Alameda County residents. Am J Epidemiol 2017; 185:1070-88.,¹³13. Minagawa Y, Saito Y. Active social participation and mortality risk among older people in Japan: results from a nationally representative sample. Res Aging 2015; 37:481-99.,¹⁴14. Wu J, Li J. The impact of social participation on older people's death risk: an analysis from CLHLS. China Popul Dev Stud 2018; 2:173-85.. Our findings also suggest an inverse association between economic conditions (schooling level and occupation) and mortality for older ages. We found that older adults with higher education levels had a lower risk of mortality during follow-up than those with lower levels, corroborating with previous evidence from Chile ¹⁹19. Sandoval MH, Turra CM. El gradiente educativo en la mortalidad adulta en Chile. Revista Latinoamericana de Población 2015; 9:1-29.,²⁰20. Sandoval MH, Turra CM, Luz L. The importance of education for middle- and old-age mortality in Chile: estimates from panel data linked to death records. J Aging Health 2021; 34:71-7. and other societies ²¹21. Elo IT, Preston SH. Educational differentials in mortality: United States, 1979-85. Soc Sci Med 1996; 42:47-57.,²²22. Liu X, Hermalin AI, Chuang Y-L. The effect of education on mortality among older Taiwanese and its pathways. J Gerontol B Psychol Sci Soc Sci 1998; 53:S71-82.,²³23. Hummer RA, Lariscy J. Educational attainment and adult mortality. In: Rogers RG, Crimmins EM, editores. International handbook of adult mortality. Dordrecht: Springer; 2010. p. 241-61.,²⁴24. Luo Y, Zhang Z, Gu D. Education and mortality among older adults in China. Soc Sci Med 2015; 127:134-42.. We also found that the type of living arrangement of older adults influences their longevity. As an example, those who live alone had higher mortality risk than those who live with their partners and children. These results corroborate with previous study ²⁵25. Sandoval MH, Alvear M. Arreglos residenciales y mortalidad de adultos mayores en Chile, 2004-2016. In: Octavo Congreso de la Asociación Latinoamericana de Población: Población y Desarrollo Sostenible Políticas Públicas y Avances en la Medición Sociodemográfica. Puebla: Asociación Latinoamericana de Población; 2018. p. 1-14.. However, Model 3 shows that this risk is higher for those who live in other types of arrangements and even those who live alone with their children, which could be associated with socioeconomic conditions. That is, those who live alone have access to greater material resources, institutional care, private medical services, and better overall health. On the other hand, in Model 4, health status variables increase the mortality risk of living alone compared to other living arrangements, possibly because other types of arrangement are more likely to receive direct care. Not all categories of the living arrangement variable were statistically significant in the full model (Model 4); however, a joint test (Wald test) indicates significance at 1% (p-value = 0.007).

As expected, the protective effect of social participation on mortality risk remains significant despite decreasing with added health status variables. Some studies support social activity as an essential component for healthy aging ²⁶26. Rowe J, Kahn R. Successful aging. Gerontologist 1997; 37:433-40.. As aforementioned, social activity influences a series of health-related results, including lower risk of disability - such as performing basic personal and IADL - and cognitive ability, among other issues ³3. Berkman LF, Syme SL. Social networks, host resistance, and mortality: a nine-year follow-up study of Alameda County residents. Am J Epidemiol 2017; 185:1070-88.,⁶6. Gao M, Sa Z, Li Y, Zhang W, Tian D, Zhang S, et al. Does social participation reduce the risk of functional disability among older adults in China? A survival analysis using the 2005-2011 waves of the CLHLS data. BMC Geriatr 2018; 18:224.,⁷7. Buchman A, Boyle P, Wilson RS, Fleischman D, Leurgans S, Bennett DA. Association between late-life social activity and motor decline in older adults. Arch Intern Med 2009; 169:1139-46.,⁸8. Berkman LF, Glass T, Brissette I, Seeman TE. From social integration to health: Durkheim in the new millennium. Soc Sci Med 2000; 51:843-57.,⁹9. Engelhardt H, Buber I, Skirbekk V, Prskawetz A. Social involvement, behavioural risks and cognitive functioning among older people. Ageing Soc 2010; 30:779-809.,¹⁰10. Wang H-X, Karp A, Winblad B, Fratiglioni L. Late-life engagement in social and leisure activities is associated with a decreased risk of dementia: a longitudinal study from the Kungsholmen project. Am J Epidemiol 2002; 155:1081-7.,¹¹11. Wilson RS, De Leon CFM, Bienias JL, Evans DA, Bennett DA. Personality and mortality in old age. J Gerontol B Psychol Sci Soc Sci 2004; 59:110-6.,¹³13. Minagawa Y, Saito Y. Active social participation and mortality risk among older people in Japan: results from a nationally representative sample. Res Aging 2015; 37:481-99.,¹⁴14. Wu J, Li J. The impact of social participation on older people's death risk: an analysis from CLHLS. China Popul Dev Stud 2018; 2:173-85.,²⁷27. James BD, Wilson RS, Barnes LL, Bennett DA. Late-life social activity and cognitive decline in old age. J Int Neuropsychol Soc 2011; 17:998-1005.. Regardless of the health results used, evidence shows that social participation is a stronger predictor of health and longevity.

For Latin America, effects of social participation on mortality in older adults are still indefinite. Gontijo et al. ²⁸28. Gontijo CF, Firmo JOA, Lima-Costa MF, Loyola Filho AI. A longitudinal study of the association between social capital and mortality in community-dwelling elderly Brazilians. Cad Saúde Pública 2019; 35:e00056418. found that in Brazil, specifically in the municipality of Bambuí, social participation is associated with a lower mortality rate among older adults. Similarly, Hill et al. ²⁹29. Hill TD, Saenz JL, Rote SM. Religious participation and mortality risk in Mexico. J Gerontol B Psychol Sci Soc Sci 2020; 75:1053-61. showed that, in Mexico, higher religious participation is related to lower mortality risk. This study results contribute to the literature on this topic available in Latin America, confirming that social life not only improves emotional, affective, and economic aspects but also increases longevity. Older adults who do not participate in any social activity thus hinder their opportunities of enjoying a long life.

This study has limitations. Firstly, we cannot know if the association between social participation and mortality varies with the frequency that an organization is visited - as other authors have suggested - because of the lack of information about the frequency of attendance in the different organizations. Today the literature diverges on how to operationalize the social participation variable. Some studies have elaborated synthetic indexes of social participation ⁴4. Laugesen K, Baggesen LM, Schmidt SAJ, Glymour MM, Lasgaard M, Milstein A, et al. Social isolation and all-cause mortality: a population-based cohort study in Denmark. Sci Rep 2018; 8:4-11.,⁵5. Rodriguez-Laso A, Zunzunegui MV, Otero A. The effect of social relationships on survival in elderly residents of a Southern European community: a cohort study. BMC Geriatr 2007; 7:19., another used the membership in social organizations or associations as a proxy ¹³13. Minagawa Y, Saito Y. Active social participation and mortality risk among older people in Japan: results from a nationally representative sample. Res Aging 2015; 37:481-99., whereas others use different measures of social participation ¹⁵15. Ang S. Social participation and mortality among older adults in Singapore: does ethnicity explain gender differences? J Gerontol B Psychol Sci Soc Sci 2018; 73:1470-9.,¹⁶16. Murata C, Kondo T, Hori Y, Miyao D, Tamakoshi K, Yatsuya H, et al. Effects of social relationships on mortality among the elderly in a Japanese rural area. J Epidemiol 2005; 15:78-84.,¹⁷17. Sato T, Kishi R, Suzukawa A, Horikawa N, Saijo Y, Yoshioka E. Effects of social relationships on mortality of the elderly: how do the influences change with the passage of time? Arch Gerontol Geriatr 2008; 47:327-39., including the division between secular and religious participation ¹⁴14. Wu J, Li J. The impact of social participation on older people's death risk: an analysis from CLHLS. China Popul Dev Stud 2018; 2:173-85.. Nevertheless, regardless of the measure of social participation used, the results indicate that older adults should maintain an active life and a high attendance at social activities for a healthier and longer life.

Secondly, we could not measure the effect of possible variations in social participation on the mortality risk in older adults because of the cross-sectional nature of the data. Moreover, we believe that the effect of social participation on mortality in older age begins in the early years. Calvin et al. ³⁰30. Calvin CM, Batty GD, Brett CE, Deary IJ. Childhood club participation and all-cause mortality in adulthood: a 65-year follow-up study of a population-representative sample in Scotland. Psychosom Med 2015; 77:712-20. found that, for Scotland, having an affiliation or membership in a club at 18 years old was related to a reduced risk of death in older ages, especially at 78 years old. In other words, the effect of social participation over mortality risk does not begin with the late stages of life, but results from an accumulative process throughout the life cycle. Future studies could address the factors that interact with social participation throughout a lifetime to identify how those interactions influence life expectancy.

This study estimated a series of models, including demographic, economic, living arrangements, and health variables. However, social participation can also be associated with mortality risk based on other factors, including psychological or neuronal aspects that affect social participation in older people. Future investigations must therefore explore the association between social participation and mortality in old ages by separately analyzing the engagement and frequency in the different social organizations, which we grouped in a single variable. Moreover, we believe that including questions regarding older adults’ use of time is essential. According to the National Time-use Survey (2015) ³¹31. Instituto Nacional de Estadísticas. Encuesta Nacional Sobre Uso del Tiempo. Documento de principales resultados - ENUT 2015. https://www.ine.cl/docs/default-source/uso-del-tiempo-tiempo-libre/publicaciones-y-anuarios/publicaciones/documento_resultados_enut.pdf?sfvrsn=cf66dad0_7 (accessed on 20/Mar/2021).
https://www.ine.cl/docs/default-source/u... , older people become more involved in social activities that take place during weekdays than other age groups (3.6% older people vs. 2.7% total population), and women usually have higher social participation than men (3 hours vs. 2 hours and 31 minutes, respectively).

Gender differences in the association between social participation and mortality risk must also be studied considering the differences in which men and women construct their processes of social participation in old age, which somehow protect some more than others.

Finally, as the country moves forward regarding longitudinal data collection, we believe that this information could support in-depth investigations on the changes of the social participation variable and covariates over time, especially those related to health conditions and their association with mortality risk in older adults.

Conclusion

This study results confirm that social participation significantly protects people against mortality in old age in highly unequal societies, including that of Chile. Since it can be modified by public policies, we consider that our study is useful to elaborate public policies that promote the social participation of older adults, especially in Latin American countries, where the older population will increase at varying rates because of a demographic transition.

This study contributes to the Chilean literature on the association between social participation and mortality in advanced ages by an empirical examination in the country. Our results can be used to design public policies that promote social participation both in Chile and other Latin American countries since they establish an association between social participation and life expectancy.

Finally, Chile must promote active aging and social participation for both late and early stages of life with several public policies, considering the association between social participation and mortality. Corroborating with evidence from other regions, we found that active participation or engagement in social organizations greatly contributes to improved health and survival.

Acknowledgments

This research used information from the National Service for the Elderly (SENAMA) from the Government of Chile. The authors acknowledge the SENAMA for allowing them to access the databases. This study was supported by the Chilean National Research and Development Agency (ANID) (PAI - Convocatoria Nacional Subvención a Instalación en la Academia 2019, Folio 77190035). The results of this study are responsibility of the authors, and they do not in any way commit to both institutions.

References

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