Invited

Social Capital and Its Predictive Role in Quality of Life among the Elderly Referring to Health Centers in Tabriz, Iran: A Community- Based Study

Introduction

Population aging phenomenon has been considered to be one of the most significant socioeconomic and health challenges of the 21^th century. ^1,2 Increased rate of aged people in developing countries is significantly higher than that of the developed ones. According to a report by World Health Organization (WHO), up to 2050, almost 80% of elderly people will be living in low- and middle-income countries (LMIC). ³ Simultaneous to the global population growth, Iran is facing increase in the number of aged people. ⁴ Expanding life is not the sole aim of modern science, rather, it must try to prepare a ground on which aged people spend their lives with physical/psychological health and calmness. ⁵ Therefore, parallel to the increase in the number of aged people, enough attention must be paid to their quality of life (QOL) and identifying the effective factors on their QOL to design comprehensive and proper policies regarding elderly people. ⁶

As defined by WHO, QOL is people’s perception of their own cultural position and system of values. It is associated with their perception of their own expectations, norms, and emotions. ⁷ QOL domains cover different physical, psychological, social and environmental dimensions. ⁸ It is clear that by the increase in age, elderly people become more prone to the chronic diseases, ⁹ loneliness isolation, and lack of social support, all of which can decrease the elderly’s QOL. ¹⁰

The more social solidarity there is in a society, the healthier the society will be. ¹¹ Health is a prerequisite for QOL ¹² The elderly people’s QOL and its relation to social capital are of prime importance. Social capital includes personal and social factors that impalpably affect the elderly’s health. ^13-15 It is comprised of 8 domains of social participation, social agency and context, trust and security, interactions with neighbors, interactions with family and friends, tolerance and acceptance of differences, job interactions, and value of life which are determining factors in terms of a successful and healthy elderly life that can promote QOL. ¹⁶ Kaplan and Lynch defined social capital as a type of capital accumulation that contributes to social solidarity, social devotion, self-confidence and healthiness. ¹⁷

Social capital and its compromising elements lower down stress and anxiety and increase self-confidence through increasing communication, disseminating knowledge on promoting health, providing easier access to resources, preserving healthy behavior, providing financial and emotional support, facilitating collective interactions like social support and participation. Through all these factors, social capital can bring vitality and physical health to elderly people. ^18,19 The effect of social capital on health is more than economic and cultural capitals. Unfortunately, its role has been blurred by the passage of time. Social relations can decrease sense of loneliness and decrease risky behaviors, increase sense of powerfulness, and promotes the elderly health. ²⁰ Health policymakers and experts can utilize social capital as an intellectual framework to find out ways of activating elderly people in order to preserve their interactions in social and civil activities. ²¹

Noghani and Razavizadeh emphasized the relation between social capital and healthin a systematic review. ²² Social capital can enhance people’s adaptability, ²³ promote healthy behaviors, ^24,25 increase trust and cooperation, decrease daily stress-generating factors ²⁶ and decrease health inequalities. ²⁷ Moreover, social capital provides healthy and independent participation and the elderly people’s presence in the community. ²⁸

In view of the increasing rate of population aging, alterations in population pyramid, and changes in the type of Iranian families from extended to nucleus type and also considering the generated gap between the elderly and young people and also little social participation, it seems critical that we focus on QOL of elderly people who are the most vulnerable in the community.

The extensive review of literature did not yield any research to have investigated the predictive role of social capital on QOL of the elderly. Moreover, due to different cultural, social, and economic features of people in different regions, and there being no standard questionnaires to measure QOL and social capital by the majority of papers, there seems to be a pressing need for the present study to be conducted. Therefore, the current investigation was carried out to determine social capital and its predictive role on the QOL of elderly people who lived in city of Tabriz, East Azerbaijan province, Iran.

Materials and Methods

The current cross-sectional study on elderly people was carried out in 2018 in the city of Tabriz, north-west of Iran. Based on the annual report by Iranian Statistics Center (2016), Tabriz population was 1558693 and its elderly people were 174158. ²⁹ The studied population included all aged people, living in Tabriz and being 60 or higher. The inclusion criteria were age ≥60 years, a willingness to participate, being able to communicate, living in Tabriz, having medical records and the absences of any cognitive, psychological, and visual/hearing impairment. The exclusion criterion was incomplete completion of questionnaires more than 20%. To calculate the sample size (confidence interval [CI] of 95%, test power of 0.9), was determined using two-tailed test and STATA software (version 14) and it was calculated to be 261 with 0.2 correlation. According to the structure of cluster sampling, the number was then multiplied by 2 and the total sample size was calculated to be 522.

The sampling was in a type of multi-stage cluster sampling done in health complexes all around the city. A health center is a unit located inside the city covering approximately 12 000 people on average. ³⁰ Health centers are managed by health complexes, each health complexes containing at least 3 to 5 health centers. First of all, using http://www.random.com, 7 out of 20 all health complexes were randomly selected and from each health complexes 2 health care centers were then randomly picked. Next, according to the population info, the proper sample size based on the main sample size and proportionate to the health center size was calculated and again, using https//www.random.com, the people were randomly selected from all elderly people aged ≥60 years. Then utilizing Integrated Health System of Sib (http://sib.sbmu.ac.ir) people’s info and phone numbers were extracted. The elderly were contacted via phone calls and were briefly debriefed about the aim and methodology. In case of willingness, they were asked to be present at the health center in pre-arranged time. In case of unresponsiveness, absence of inclusion criteria or unwillingness to participate, the next elderly was randomly selected. In a meeting, the objective was clearly explained to the participants and the inclusion criteria were rechecked again. If eligible, the written consent form was taken and the questionnaires were filled in the form of interviews and in a silent room.

The questionnaires applied included items on demographics such as age, gender, weight, height, body mass index (BMI), marital status, education, number of children, economic status, health status, occupation, living conditions (living alone or with children, etc.), and probable diseases. The social capital questionnaire (Onyx & Bullen) included 36 questions covering 8 domains of social participation, social agency and context, trust and security, interactions with neighbors, interactions with family and friends, tolerance and acceptance of differences, job interactions and value of life. The scoring range is 36-144. Higher number connotes stronger social capital and vice versa. In a study by Rajabi Gilan et al., a factor analysis was done by Varimax method and the correlation coefficient of the questionnaire was calculated to be in a range of 0.52 to 0.87 with the reliability being 0.84. ³¹ The reliability of the questionnaire was evaluated by Onyx and Bullen., using Cronbach’s alph on 40 statistical populations and it was approved as acceptable. ³² In Eftekharian et al., study, conducted in the city of Sari (north of Iran), they concluded that Onyx & Bullen questionnaire was efficient enough to be implemented on the elderly, and with Cronbach’s alpha coefficient being 0.96, it acquired the highest reliability. ²⁰

WHOQOL-BREF questionnaire includes 26 items covering 4 domains of physical health, psychological health, social relation, and environment. The scoring range for physical health is 7-35, for psychological health it is 6-30, and for social relation and environment it is 3-15 and 8-40, respectively. The total scoring range is 24-120. After the raw scores in 4 domains were calculated, the total score was turned into 100 scoring format. Research on psychometric characteristics of short form of the questionnaire revealed that discriminant validity, content validity, internal reliability (Cronbach’s alpha for physical health = 0.80, psychological health = 0.76, social relation = 0.66, and environment = 0.80) and test-retest reliability were desirable. In Iran, the validity and reliability of this questionnaire was approved by Nejat et al. ³³

The reliability of the questionnaire was approved by 10 academic staff members of the Faculty of Nursing and Midwifery of Tabriz University of Medical Sciences. Moreover, the reliability of the social capital questionnaire and its domains were calculated by Cronbach’s alpha for the participation in local community = 0.70, social agency = 0.65, trust and safety = 0.61, interaction with neighbors = 0.63, interaction with family = 0.60, tolerance and acceptance of differences = 0.92, job interactions = 0.63, value of life = 0.61 and the total social capital = 0.87. The reliability of QOL questionnaire and its domains, using Cronbach’s alpha, was calculated to be 0.83 for physical health, 0.72 for psychological health, 0.60 for social relation, 0.75 for environment and the total QOL = 0.90.

The normality of data distribution was evaluated, utilizing Kolmogorov-Smirnov test. The data were analyzed by SPSS software (version 15). Descriptive data were depicted as frequency, percentage, mean (SD) and for the analytical data Pearson test and multivariate linear regression were applied and P <0.05 was considered to be statistically significant.

Bivariate statistical tests such as independent t test and one-way analysis of variance (ANOVA) were used to analyze the relation between QOL and socio-demographic characteristics. Then, the independent variables with P <0.2 in the bivariate tests were entered into the multivariate linear regression model with backward strategy to control the confounding variables and to measure the respective effects of the social capital on QOL. Before conducting multivariate analysis, the assumptions of the regression including normality of the residuals, homogeneity of the residual variance, multicollinearity of independent variables, and independence of the residuals were studied.

Results

To access the needed sample size, considering the eligibility criteria, 667 elderly, covered by health centers, were randomly selected from April to August 2018. Finally, 522 eligible participants were enrolled in the study and filled the questionnaires. The mean )SD( of participants’ age was 65.55 )5.39(. More than half were women and most of them were married (85.5%). One third was illiterate (37.5%). More than half were middle income people (57.9%). Table 1 illustrates more details.

Mean (SD) of the total score of social capital and elderly QOL were, respectively, 71.87 )10.51( and 64.64 (10.88(. Table 2 shows the scores of different domains of social capital and QOL.

According to the Pearson test there was a direct and significant relation between QOL and its domains and the total social capital (P  ˂ 0.05). The highest correlation was between the dimension of social relation health QOL and social capital (P ˂ 0.01, r=0.436) (Table 3).

According to the regression analysis adjusted for context variables, there was a significant relation between social capital and QOL (P  ˂ 0.05) in a way that, QOL scores increased by increment of capital increased. Moreover, there was a significant relation between variables including marital status, education, economic status, health status and the absence of cardiovascular diseases (CVDs) and joint pains with QOL (Table 4).

Discussion

The aim of current study was to evaluate the social capital and its predictive role on QOL of elderly people in Tabriz. The findings revealed that the mean (SD) social capital among the elderly was 71.87 (10.51) (scoring range 36-144) indicating undesirable social capital. This finding is in accordance with Akbari et al., study in Sanandaj, Iran in 2016. The mean score of social capital among women at the age range of 17-80 was reported to be 76 based on Onyx& Bullen questionnaire. ³⁴ It is also in line with that of Moradian Sorkhkalaee et al., in 2012 with the mean age of 20.55 in students of Tehran University of Medical Sciences which reported the mean social capital using the above questionnaire as 43.87 out of 100. ³⁵ Research has revealed that social capital among men/women with different ages was low and thus, necessary actions must be taken to enhance social capital at lower ages in both genders.

Findings of the current investigation indicated that mean score of QOL of the elderly in Tabriz was 64.64 (10.88) from 0-100, similar to the studies with the same questionnaire on the elderly people in Iran ³⁶ and India-Puducherry city. ³⁷ The mean score of QOL in these studies were 52.2 (20.2) and 49.74 (10.21), respectively. Baernholdt et al., reported high level of QOL among American elderly people. ³⁸ An investigation by Raggi et al., also revealed higher level of QOL among Finnish elderly and adults. ³⁹ These results showed that QOL in developing countries was relatively lower. Population aging is increasing in developing countries; in fact, QOL shows their health and welfare status. Therefore, necessary measures should be considered to enhance QOL in these countries and the plans already implemented in developed countries can be fruitful in this regard.

In the current study, there was a significant relation between marital status, education, economic status, health status, and the absence of CVDs/ joint pains with QOL.

There was a relation between marital status and QOL in this investigation which is in agreement with that of Pishgooie et al., who studied people with coronary diseases. ⁴⁰ It is also in line with Mwanyangala et al., ⁴¹ and Şahingöz & Şhahin ⁴² studying elderly people who indicated that marriage contributes to psychological health, which in turn enhances QOL among elderly people.

The current study revealed a relation between education and QOL of elderly people, which had also been reported in studies by Luthy et al., ⁴³ Shaabani et al., ⁴⁴ Lee et al., ⁴⁵ Ganesh Kumar et al., ³⁷ and Hongthia et al. ⁴⁶ Education enhances self-confidence and knowledge about health, which contributes to more mental and physical health and better QOL.

Better economic status also increased QOL. This finding is in agreement with Campos et al. ⁴⁷ Convenient economic status provides individuals with better services and healthier options which in turn, results in better QOL.

Health status was also related to QOL. Campos et al., ⁴⁷ and Layte et al., ⁴⁸ also confirmed this finding. Good mental and physical health can cause better QOL.

Current study also demonstrated that CVD is related to QOL. It was also indicated by Ekman et al., ⁴⁹ Tran et al., ⁵⁰ CVDs decreases QOL. This fact emphasizes the significance of focusing on QOL of CVD patients.

Joint pains were also found to affect QOL. Hu et al., ⁵¹ pointed out the same issue. These pains decrease QOL, making QOL to be intertwined with these pains among the elderly.

Our findings showed that by adjusting context variables, social capital can play a predictive role in QOL of elderly people. So that social capital score is enhanced by increasing QOL score. Lucumi et al., ¹⁶ studying Colombian elderly in 2007, Nilsson et al., focusing on the rural elderly in Bangladesh, ⁵² Ma et al., exploring AIDS in Chinese patients, ⁵³ Abdul-Hakim et al., focusing on Malaysian rural families, ⁵⁴ Karimzadeh studying the Indian families, ⁵⁵ Rajabi Gilan et al., focusing on teachers, ³¹ Moradian Sorkhkalaee et al., on health staff ¹⁸ all highlighted the relation between social capital and QOL. Social capital affects QOL by transferring health information, promoting health behaviors, and lowering down stress and poverty. ⁵⁴

The advantages of this community-based study were accurate completion of the questionnaire and randomized sampling. There were also some limitations, among which the absence of generalizability of the present study to the whole country might be an obvious one. It was also impossible to include all elderly people. Furthermore, the participation of the female and active elderly people was more than others in this study. It is recommended that in further future studies, the questionnaires should be filled in at the elderly people homes so that all could have the chance to participate.

Conclusion

In view of the increasing rate of aging of global population, the elderly people’s QOL, especially those who are living in developing country should be greatly focused on, so that they would lead a more active and successful life. Changing the structures of families toward nucleus families, aged people retirement, different chronic diseases in this age range, children’s marriage and migration to other cities or countries have degraded social relationships and resulted in decreased social capital among the elderly people. Humans are social creatures and social capital is among determining factors of health. By increasing communications, promoting healthy behaviors, reducing loneliness, enhancing the accessibility to resources all of which decrease stress, social capital can enhance health, vitality, and self-confidence among the elderly people.

Health authorities and policymakers should design diverse and dynamic educational plans to provide cultural and socioeconomic backgrounds for the promotion of social capital among the elderly people. Also, they should design approaches to enhance elderly people’s presence in social groups and social media.

Acknowledgement

The present study was extracted from an M.Sc thesis on nursing and was approved and supported financially by Research Vice Chancellor of Tabriz University of Medical Sciences. Hereby, we appreciate the administrators and staff of Health Chancellor as well as health care centers, and all the elderly participating who contributed to our data collection process.

Ethical Issues

The study was registered and approved by the Committee of Ethics of Tabriz University of Medical Sciences (IR.TBZMED.REC.1396. 1168).

Conflict of Interest

The authors declare no conflict of interest.

Author’s Contributions

All the authors contributed to the conception and design of the study. ZNK and AFK wrote the first draft of the paper. ShBA and VP revised the manuscript. ZNK and MAJ have analyzed the research data. All authors read and approved the final manuscript.

Research Highlights

References

1. Rahimi A, Anosheh M, Ahmadi F, Foroughan M. Exploring the nature of the elderly people life style: a grounded theory. Salmand: Iranian Journal of Ageing 2016; 10(4):112-31.
2. Angelini V, Cavapozzi D, Corazzini L, Paccagnella O. Age, health and life satisfaction among older Europeans. Soc Indic Res 2012; 105(2):293-308. doi: 10.1007/s11205-011-9882-x [Crossref]
3. World Health Organization (WHO). World Report on Ageing and Health. WHO; 2015. Available From: https://www.who.int/ageing/events/world-report-2015-launch/en/.
4. Kousheshi M, Khosravi A, Alizadeh M, Torkashvand M, Aghaei N. Population Ageing in IR Iran, Socio-Economic, Demographic and Health Characteristics of the Elderly: Issues and Challenges. UNFDP Report. Tehran: Tehran University of Medical Sciences; 2014. [Persian].
5. Salar A, Boryri T, Khojasteh F, Salar E, Jafari H, Karimi M. Evaluating the physical, psychological and social problems and their relation to demographic factors among the elderly in Zahedan city during 2010-2012. Feyz Journal of Kashan University of Medical Sciences 2013; 17(3):305-11.
6. Alipour F, Sajadi H, Foruzan A, Biglarian A, Jalilian A. Elderly quality of life in Tehran’s district two. Salmand: Iranian Journal of Ageing 2008; 3(3):75-83.
7. Murphy ME, Holzer CE, 3rd, Richardson LM, Epperson K, Ojeda S, Martinez EM. Quality of life of young adult survivors of pediatric burns using World Health Organization Disability Assessment Scale II and Burn Specific Health Scale-Brief: a comparison. J Burn Care Res 2015; 36(5):521-33. doi: 10.1097/bcr.0000000000000156 [Crossref]
8. Skevington SM, Lotfy M, O’Connell KA. he World Health Organization’s WHOQOL-BREF quality of life assessment: psychometric properties and results of the international field trial. A report from the WHOQOL group. Qual Life Res 2004; 13(2):299-310. doi: 10.1023/b:qure.0000018486.91360.00 [Crossref]
9. Bols E, Smits L, Weijenberg M. Healthy living: the European congress of epidemiology, 2015. Eur J Epidemiol 2015; 30(8):709-1001. doi: 10.1007/s10654-015-0072-z [Crossref]
10. Habibi A, Nemadi-Vosoughi M, Habibi S, Mohammadi M. Quality of life and prevalence of chronic illnesses among elderly people: a cross-sectional survey. Journal of Health 2012; 3(1):58-66.
11. Shoja M, Nabavi S, Kassani A, Bagheri Yazdi SA. Factor analysis of social capital and its relations with mental health of older people in 9 districts of Tehran. Journal of North Khorasan University of Medical Sciences 2012; 3(5):81-90. doi: 10.29252/jnkums.3.5.S5.81.[Persian] [Crossref]
12. Imanzadeh A, Hamrahzdeh M. Identification of facilitators and deterrents of the quality of life in elderly women and men: a phenomenological research. Salmand: Iranian Journal of Ageing 2018; 12(4):430-45. doi: 10.21859/sija.12.4.430. [Crossref]
13. Richardson J. . Handbook of Theory and Research for the Sociology of Education 1986.
14. Coll-Planas L, Nyqvist F, Puig T, Urrútia G, Solà I, Monteserín R. Social capital interventions targeting older people and their impact on health: a systematic review. J Epidemiol Community Health 2017; 71(7):663-72. doi: 10.1136/jech-2016-208131 [Crossref]
15. Hsieh CH. A concept analysis of social capital within a health context. Nurs Forum 2008; 43(3):151-9. doi: 10.1111/j.1744-6198.2008.00107.x [Crossref]
16. Lucumí DI, Gomez LF, Brownson RC, Parra DC. Social capital, socioeconomic status, and health-related quality of life among older adults in Bogotá (Colombia). J Aging Health 2015; 27(4):730-50. doi: 10.1177/0898264314556616 [Crossref]
17. Lynch JW, Kaplan GA. Understanding how inequality in the distribution of income affects health. J Health Psychol 1997; 2(3):297-314. doi: 10.1177/135910539700200303 [Crossref]
18. Moradian Sorkhkolaee M, Esmaeili Shahmirzadi S, Sadeghi R, Nikooseresht Z, Fard F. The relationship between quality of life and social capital among health workers in medical and health network of Rey city in 2012. Razi Journal of Medical Sciences 2013; 20(114):69-77.
19. Murayama H, Fujiwara Y, Kawachi I. Social capital and health: a review of prospective multilevel studies. J Epidemiol 2012; 22(3):179-87. doi: 10.2188/jea.je20110128 [Crossref]
20. Eftekharian R, Kaldi A, Sum S, Sahaf R, Fadaye Vatan R. Validity and reliability of Persian version of Onyx Social Capital Scale in elderly people. Salmand: Iranian Journal of Ageing 2016; 11(1):Salmand: Iranian Journal of Ageing. doi: 10.21859/sija-1101174 [Crossref]
21. Isbel ST, Berry HL. Social capital, health, and elderly driver status. Yale J Biol Med 2016; 89(1):87-90.
22. Noghani M, Razavizadeh N. Social capital and health: a return to social and sociological traditions. Journal of Research and Health 2013; 3(1):286-94.
23. Shoja M, Rimaz S, Asadi-Lari M, Bagheri Yazdi SA, Gohari MR. Mental health of older people and social capital. Iranian Institute for Health Sciences Research 2013; 12(4):345-53.
24. Fujiwara T, Kawachi I. A prospective study of individual-level social capital and major depression in the United States. J Epidemiol Community Health 2008; 62(7):627-33. doi: 10.1136/jech.2007.064261 [Crossref]
25. De Silva MJ, Huttly SR, Harpham T, Kenward MG. Social capital and mental health: a comparative analysis of four low income countries. Soc Sci Med 2007; 64(1):5-20. doi: 10.1016/j.socscimed.2006.08.044 [Crossref]
26. De Clercq B, Vyncke V, Hublet A, Elgar FJ, Ravens-Sieberer U, Currie C. Social capital and social inequality in adolescents’ health in 601 Flemish communities: a multilevel analysis. Soc Sci Med 2012; 74(2):202-10. doi: 10.1016/j.socscimed.2011.10.025 [Crossref]
27. Pons-Vigués M, Diez È, Morrison J, Salas-Nicás S, Hoffmann R, Burstrom B. Social and health policies or interventions to tackle health inequalities in European cities: a scoping review. BMC Public Health 2014; 14:198. doi: 10.1186/1471-2458-14-198 [Crossref]
28. Nyqvist F, Nygård M, Steenbeek W. Social capital and self-rated health amongst older people in Western Finland and Northern Sweden: a multi-level analysis. Int J Behav Med 2014; 21(2):337-47. doi: 10.1007/s12529-013-9307-0 [Crossref]
29. Iranian Census Bureau. The results of the General Census of Population and Housing. [Internet] [ 2016; cite 18 Jan 2018]. Available from: https://www.amar.org.ir.
30. Milani MJ, Arshadi FS, Noghabi AA. . Text book of Community Health Nursing 2004.
31. Rajabi Gilan N, Ghasemi SR, Reshadat S, Rajabi S. The relationship between social capital and health-related quality of life among teachers. Journal of Advances in Medical and Biomedical Research 2013; 21(88):95-107.
32. Onyx J, Bullen P. Measuring social capital in five communities. J Appl Behav Sci 2000; 36(1):23-42. doi: 10.1177/0021886300361002 [Crossref]
33. Nejat S, Montazeri A, Holakouie Naieni K, Mohammad K, Majdzadeh SR. The World Health Organization quality of life (WHOQOL-BREF) questionnaire: translation and validation study of the Iranian version. Journal of School of Public Health and Institute of Public Health Research 2006; 4(4):1-12.
34. Akbari M, Najafi S, Nadrian H. The relationship between social capital perceived social support and the women’s mental health in Sanandaj: a community-based study. Iranian Journal of Health Education and Health Promotion 2017; 5(3):155-63. doi: 10.30699/acadpub.ijhehp.5.3.155.[Persian] [Crossref]
35. Moradian Sorkhkalaee M, Eftekhar Ardebili H, Nedjat S, Saiepour N. Social capital among medical students of Tehran University of Medical Sciences in 2011. Razi Journal of Medical Sciences 2012; 19(102):30-7.
36. Nedjat S, Holakouie Naieni K, Mohammad K, Majdzadeh R, Montazeri A. Quality of life among an Iranian general population sample using the World Health Organization’s quality of life instrument (WHOQOL-BREF). Int J Public Health 2011; 56(1):55-61. doi: 10.1007/s00038-010-0174-z [Crossref]
37. Ganesh Kumar S, Majumdar A, Pavithra G. Quality of life (QOL) and its associated factors using WHOQOL-BREF among elderly in urban Puducherry, India. J Clin Diagn Res 2014; 8(1):54-7. doi: 10.7860/jcdr/2014/6996.3917 [Crossref]
38. Baernholdt M, Hinton I, Yan G, Rose K, Mattos M. Factors associated with quality of life in older adults in the United States. Qual Life Res 2012; 21(3):527-34. doi: 10.1007/s11136-011-9954-z [Crossref]
39. Raggi A, Corso B, Minicuci N, Quintas R, Sattin D, De Torres L. Determinants of quality of life in ageing populations: results from a cross-sectional study in Finland, Poland and Spain. PLoS One 2016; 11(7):e0159293. doi: 10.1371/journal.pone.0159293 [Crossref]
40. Pishgooie AH, Zare Shorakie H, Zareiyan A, Atashzadeh Shoorideh F, Forghani M. Evaluation of quality of life and its effective factors in military patients and relatives with coronary artery disease in Tehran, Iran, 2016-a cross sectional study. Journal of Military Medicine 2018; 20(2):212-21.
41. Mwanyangala MA, Mayombana C, Urassa H, Charles J, Mahutanga C, Abdullah S, et al. Health status and quality of life among older adults in rural Tanzania. Glob Health Action 2010; 3. 10.3402/gha.v3i0.2142
42. Şahingöz SA, Şahin H. An examination of the quality of life of elderly people: a Turkey-Aksehir sample. Int J Educ Res 2013; 1(5):1-10.
43. Luthy C, Cedraschi C, Allaz AF, Herrmann FR, Ludwig C. Health status and quality of life: results from a national survey in a community-dwelling sample of elderly people. Qual Life Res 2015; 24(7):1687-96. doi: 10.1007/s11136-014-0894-2 [Crossref]
44. Shaabani J, Rahgoi A, Nourozi K, Rahgozar M, Shaabani M. The relationship between self-efficacy and quality of life among elderly people. Salmand: Iranian Journal of Ageing 2017; 11(4):Iranian Journal of Ageing 2017; 11(4). doi: 10.21859/sija-1104518 [Crossref]
45. Lee TW, Ko IS, Lee KJ. Health promotion behaviors and quality of life among community-dwelling elderly in Korea: a cross-sectional survey. Int J Nurs Stud 2006; 43(3):293-300. doi: 10.1016/j.ijnurstu.2005.06.009 [Crossref]
46. Hongthai K, Treesorn K, Pongpoottipat R. Factors correlated quality of life of the elderly people in residential homes for the elderly. Review of Integrative Business and Economics Research 2014; 3:16-23.
47. Campos AC, Ferreira e Ferreira E, Vargas AM, Albala C. Aging, gender and quality of life (AGEQOL) study: factors associated with good quality of life in older Brazilian community-dwelling adults. Health Qual Life Outcomes 2014; 12:166. doi: 10.1186/s12955-014-0166-4 [Crossref]
48. Layte R, Sexton E, Savva G. Quality of life in older age: evidence from an Irish cohort study. J Am Geriatr Soc 2013; 61 Suppl 2:S299-305. doi: 10.1111/jgs.12198 [Crossref]
49. Ekman I, Chassany O, Komajda M, Böhm M, Borer JS, Ford I. Heart rate reduction with ivabradine and health related quality of life in patients with chronic heart failure: results from the SHIFT study. Eur Heart J 2011; 32(19):2395-404. doi: 10.1093/eurheartj/ehr343 [Crossref]
50. Tran BX, Moir MP, Thai TPT, Nguyen LH, Ha GH, Nguyen THT. Socioeconomic inequalities in health-related quality of life among patients with cardiovascular diseases in Vietnam. Biomed Res Int 2018; 2018:2643814. doi: 10.1155/2018/2643814 [Crossref]
51. Hu Z, Man GCW, Kwok AKL, Law SW, Chu WWC, Cheung WH. Global sagittal alignment in elderly patients with osteoporosis and its relationship with severity of vertebral fracture and quality of life. Arch Osteoporos 2018; 13(1):95. doi: 10.1007/s11657-018-0512-y [Crossref]
52. Nilsson J, Rana AK, Kabir ZN. Social capital and quality of life in old age: results from a cross-sectional study in rural Bangladesh. J Aging Health 2006; 18(3):419-34. doi: 10.1177/0898264306286198 [Crossref]
53. Ma Y, Qin X, Chen R, Li N, Chen R, Hu Z. Impact of individual-level social capital on quality of life among AIDS patients in China. PLoS One 2012; 7(11):e48888. doi: 10.1371/journal.pone.0048888 [Crossref]
54. Abdul-Hakim R, Ismail R, Abdul-Razak NA. The relationship between social capital and quality of life among rural households in Terengganu, Malaysia. OIDA International Journal of Sustainable Development 2010; 1(5):99-106.
55. Karimzadeh M. Impact of social capital on quality of life: evidence from India. International Journal of Economic Practices and Theories 2013; 3(4):264-71.