Introduction:

According to the 2016 census in Iran, the number of people aged 60 years and over was 7414091 (9.28% of the Iranian population)¹. It is estimated this figure to double by 2030. It means that as the population of Iran doubles over an 11-year period, the number of elderly populations aged over 65 years will increase 6 times². The impact of this large group of elderly people on the Iranian health system deserves careful analysis. One of the major challenges of aging studies is to maintain the quality of life despite the aging-related deficiencies³. The dominant attitude toward aging is focused on the deficiencies, reduced performance, and the disabilities associated with aging. However, an ideal successful aging has psychosocial dimensions that are not associated much with physical condition and they are learned and acquired. The focus of this view is on the strengths of the elderly people, enhancing their self-efficacy, and promoting their quality of aging⁴. Based on the results of some studies, demographic characteristics such as age are associated with some indicators of successful aging such as well-being and health-related quality of life^5,6. Level of education, marital status, and number of children are factors influencing the quality of life and well-being at old age, but there are contradictions on this relationship^7-9.

Successful aging

Despite rich literature on the concept of successful aging and its dimensions, there is no consensus on a comprehensive definition of successful aging^5-7. Havighurst (1963) introduced the concept of "successful aging" for the first time¹⁰, and then, Rowe and Kahn (1997) and Baltes and Baltes (1990) expanded this concept^11,12. To show how elderly people succeed in adapting to aging, Paul Baltes and Margret Baltes (1990) proposed a successful aging model or selection, optimization and compensation model¹². They believe that successful aging is an individual evolution with three main strategies of selection, optimization and compensation. These three key processes are essential for the evolution of successful aging. Successful aging involves selecting the functional areas based on one's available resources, optimizing evolutionary potential (maximizing profit) and compensating the losses^11-14. In other words, by using the strategies of selection, optimization, and compensation model, maintaining performance and minimizing of loss during aging are guaranteed. The underlying assumption of this model is that people are exposed to a number of specific opportunities (such as education) and certain limitations in resources and capabilities (such as illness) during their life that they can cope with and overcome them through three strategies of selection, optimization, and compensation¹⁵. The successful aging model of Baltes and Baltes (1990) considers successful aging process as an appropriate, creative and individual combination of selection, optimization and compensation strategies¹⁶. The reason for choosing this model is that it considers successful aging as an evolutionary nature and deals with the psychological aspects of successful aging. Successful aging enhances the quality of life in elderly people. A review of existing studies revealed that there is no accurate information on the status of successful aging in Iran. Hence, the present study was conducted to investigate the status of successful aging in Iran and its relationship with some demographic characteristics.

Materials and methods:

The present study was a descriptive-analytical study. The study population included elderly people aged over 60 years living in Shiraz. In this study, 179 elderly people aged 60-97 years were studied. Due to the lack of a similar study, 153 samples were first collected as pilot. Considering the accuracy of 0.5 and the significance level of 0.05, standard deviation of the pilot sample was obtained at 3.41 and the final sample size was estimated at 179 people using the following formula:

Sample size determination formula

Sampling was performed through random multistage cluster sampling. Accordingly, Shiraz was divided into 4 districts and each district was subdivided into 4 regions. One park and one clinic were randomly selected from each region. The reason for the selection of parks and clinics was the results of a field study that showed that elderly people spend most of their time in parks and clinics. The researcher referred to each of the mentioned locations in morning and evening. Sampling was performed in parks and clinics using a convenience sampling method. Before starting the study, the objective of the study was explained for the subjects. Participation in the study was also voluntary. The participants were ensured that their information would remain completely anonymous and confidential. Then, their informed consent was obtained. The research inclusion criteria were: 1- Age above 60 years, 2- Willingness to participate in the study, 3- Having the skill of reading and writing in Persian. The research exclusion criterion also included any of mental and cognitive disabilities.

Data collection tools included Demographic Information Questionnaire and short form of Selection, Optimization and Compensation Questionnaire. First, demographic information questionnaire including demographic information of gender, age, marital status, level of education, and number of children were completed by researcher assistant. The short form of Selection, Optimization and Compensation Questionnaire was used to measure the mean score of successful aging. The selection component is divided into two sub-components of preference-based selection and change-based selection. The short form of Selection, Optimization and Compensation Questionnaire developed by Baltes and Baltes (1999) was used to measure the mean score of successful aging. It has 12 items, 3 items of which are related to preference-based selection, 3 are related to change-based selection, 3 are related to optimization and 3 are related compensation¹⁷.

Each item consists of two propositions. The first proposition is behavioral proposition that represents selection, optimization, or compensation strategies and other proposition is unrelated to these strategies. The related proposition receives a score of 1 and the irrelevant proposition receives a score of zero. The range of scores in each component is from 0 to 3 and the total score for whole questionnaire is between 0 and 12. Higher scores indicate higher levels of selection, optimization and compensation. The face, content, construct validities and the reliability coefficients of the questionnaire have been examined in Iran by Agilar Vafaei et al (2016)¹⁸. The face and content validities of this questionnaire were measured and evaluated at appropriate level. Cronbach's alpha was obtained at 0.64 for the whole scale and 0.63, 0.68, and 0.69, respectively, for the selection, optimization and compensation components¹⁷. The construct validity of this questionnaire was also measured by confirmatory factor analysis and its four-factor structure was confirmed. The test retest reliability with a four-week interval for this questionnaire was obtained at acceptable level (r=0.74-0.82)¹⁹. Internal reliability coefficients (Cronbach's alpha) for selection, optimization, and compensation were obtained at 0.60, 0.61, and 0.65, respectively¹⁷. The questions were read orally by the tester and the elderly people’s responses were written accurately and completely.

Statistical Analysis

The Kolmogorov-Smirnov test did not show normal distribution data. Therefore, nonparametric tests such as Spearman, Mann-Whitney and Kruskal-Wallis tests were used for data analysis. Data were analyzed through SPSS version 16 software and the significance level was considered at the level of 0.05.

Results:

A total of 179 participants (99 males and 80 females) aged 60-97 years with a mean age of 72.46 years participated in the first stage of the study. More than 55% of the participants were male. 60.4% of the participants were married and 70.4% had high school diploma and lower level of education. The number of children varied from 0 to 11. (Table 1) illustrates the demographic information of the participants (age, gender, level of education and marital status).

The mean and standard deviation of selection, optimization and compensation components are presented in (Table 2).

(Table 3) presents the relationship between some demographic characteristics including age, gender, level of education, marital status and number of children and selection, and compensation components.

According to the results, gender had no significant correlation with mean score of selection, optimization and compensation (P -value >0.05). However, the age variable had a significant and inverse correlation with the compensation strategy. It means that the mean score of compensation decreases significantly with increasing age (P- value=0.048).

Level of education had a direct and significant correlation with the mean scores of all three strategies: selection, optimization, and compensation strategies (P-value= 0.0001) (Table 3). (Table 4) presents the mean score of selection, optimization and compensation based on the level of education. According to the results, the mean score of selection (preference-selection and change-based selection) and optimization was significantly higher in elderly people with an academic level of education compared to illiterate elderly people.

Based on the results, there was an inverse and significant relationship between marital status and mean score of optimization and compensation (P-value=0.008) (Table 3). Single elderly people had the highest mean score and widowed elderly people had the lowest mean score in selection, optimization, and compensation strategies and overall aging score. The mean score of successful aging and the mean score of optimization in the widowed elderly people were significantly different from those of the other elderly people (Table 5).

Discussion:

The objective of this study was to investigate the status of successful aging and its relationship with some demographic characteristics in the elderly population of Shiraz. There are different models and theories about successful aging. The well-known model of Rowe and Kahn defines successful aging as avoiding illness and disability, maintaining the highest level of physical and cognitive function, and active involvement in life events²⁰. However, there are very few successful elderly people based on high functional criteria of this model¹³. According to Strabridge et al, 50.3% of elderly people 65 to 99 years old in the United States believed that they are successful, while only 18.8% of them considered themselves successful according to Rowe and Kahn model criteria²¹. Modern theories, such as Baltes and Baltes, consider successful aging as an individual evolution with three main components of selection, optimization, and compensation.

Accordingly, successful aging involves selecting the functional areas according to one's available resources, optimizing evolutionary potential (maximizing profit), and compensating of losses. According to this model, the definition of successful aging should include objective and subjective criteria and recognize cultural areas¹³. The status of successful aging in Iran was not clear due to the lack of necessary findings. Hence, the comparison of successful aging in Iran with other developed countries should be performed with caution. The results revealed that preference-based selection had the highest mean score among the studied elderly people and they obtained more than half of the mean score of successful aging. Based on the results of the study conducted by Freund and Baltes (2002), preference-based selection was the only component that increased in the elderly people compared to the middle-aged people¹⁹. The results revealed that age was a determining factor for successful aging, meaning that within the population bracket studied older people use less compensatory strategies than younger ones to cope with the deficiencies of aging. Compensation strategy generally reflects the ability to access and use various resources to compensate a reduction in performance due to aging. This ability decreases with increasing age. Previous studies have confirmed this issue. According to the study conducted by Freund and Baltes (1999), the use of compensation strategies decreases with increasing age²². Review of existing studies showed that the elderly people had the lowest quality of life in social-related factors^5,8.

Age has also been identified as an influencing factor in health and well-being.⁶ It seems that with increasing age, in addition to a reduction in physical efficiency, the cognitive status of the elderly people also decreases. Reduced cognitive status is an important factor with regard to the level of independence in decision-making and quality of life in elderly people. Lack of physical and mental ability reduces the chances of compensations in the elderly people. The results revealed that the mean score of compensation and the total score of the successful aging were significantly lower in the elderly people compared to younger ones. Gender did not show a significant relationship with successful aging and its dimensions. Review of existing studies showed that health-related quality of life was not significantly associated with gender of the elderly people⁸. Level of education was significantly correlated with the mean score of successful aging in all four components and total score of successful aging. Existing studies show that well-being in elderly people with a higher level of education is significantly higher than that of elderly people with a lower level of education^7,8. Education increases the opportunities for selecting the options available. On the other hand, more educated elderly people are better able to optimize their existing opportunities or, if necessary, adapt to existing conditions. Elderly people with higher level of education are able to compensate their disabilities more successfully than illiterate ones. Thus, it seems that education to be a determinant of successful aging in the elderly people. Marital status was found to be inversely correlated with successful aging, meaning that single elderly people had significantly higher scores in optimization and compensation components and overall successful aging score than married ones. This result is inconsistent with that of the study conducted by Arias-Merino et al (2012). In the above-mentioned study, married elderly people achieved a higher score of successful aging than single ones²³. These differences might be attributed to differences in sample size, sampling method, and cultural and ethnic differences. The present study was conducted on elderly people in one city, while Arias-Merino examined elderly people in two cities in western Mexico with a larger sample size. Based on Iranian-Islamic culture and beliefs, married men and women, despite having marital problems, are obliged to continue living and this issue can reduce marital satisfaction in some couples.

Existing studies emphasize the relationship between marital satisfaction and well-being and health outcomes at high ages. Accordingly, marital problems are one of the most important predictors in reducing health outcomes in the elderly people²⁴. In another study, despite the importance of marital life satisfaction on the health and well-being of the elderly people, psychological and social factors had a determining role in marital satisfaction, emotional loneliness and helplessness in the elderly people. The researchers concluded that health and well-being in the elderly people are more influenced by psychological resilience and marital problems²⁵. Also, the results of a longitudinal study revealed that poor marital quality of life has exacerbated feeling of loneliness over the next two years²⁶. In contrast, results of other study revealed that married elderly people achieved higher scores in the aging criteria, while marital status in middle-aged people was associated with more stresses²⁷. The results of Hazrati et al.'s (2017) study showed that 68.9% of couples are emotionally abused in their marital relationship²⁸. It may be concluded that the quality of marital life and satisfactory relationship with spouse have a more important role in the successful aging and health of the elderly people. Further studies are required in this regard.

Conclusion:

Studies show that having a contact with adult children increases life satisfaction at old age²⁷. In the present study, the number of children was significantly correlated with the total score of successful aging and change-based selection strategy, meaning that with increasing the number of children, the overall score of successful aging increased. Previous studies conducted on different cultures have reported conflicting information about the relationship between number of children and marital satisfaction^28,29.

The cause of these inconsistent results might be attributed to cultural differences of different communities³⁰. The results of the present study also showed that higher number of children is associated limited use of change-based selection strategies. A change-based selection strategy indicates the ability to adjust existing needs based on resources and facilities. In fact, this strategy indicates the ability to allocate scarce energy to the most important goals and needs, which is one of the important criteria for successful aging¹⁴. Having more children seems to take more energy from parents due to their involvement in the children affairs and reduce their concentration and organizing power to meet their basic needs.

Limitations and Recommendations: One of the limitations of this study was relying on the memory of the studied elderly people to complete a demographic questionnaire, which increases the probability of bias and reduces the accuracy of the study, due to reduction in normal function of memory resulting from aging in some elderly people. To address this threat, it was attempted to devote more time to remembering older people's memories. Longitudinal studies with larger sample size are needed on discovering the relationship of demographic factors with successful aging and predictors of successful aging in different cultures, especially Iran.

Acknowledgments

Acknowledgment: This study was derived from a PhD dissertation written by Giti Sotudeh under the Project Code of 16481-08-01-1396. This study was financially supported by the Research Deputy of Shiraz University of Medical Sciences. This study was also presented to Ethics Committee of Shiraz University of Medical Sciences and approved under the Ethics Code of IR.SUMS.REC.1397.394. The authors of this study hereby appreciate all elderly people who helped us in conducting this project .

References

1. Statistical Center of Iran. 2016. Retrieved at: http://irandataportal.syr.edu/census/census-2016. 1 Jan 2018

2. Mehryar, A. H. & Ahmad-Nia, Sh. (2004). Age-structural transition in Iran: short and long term consequences of drastic fertility swings during the final decades of twentieth century. Paper presented in the CICRED Seminar on “Age-Structural Transitions: Population Waves, Disordered Cohort Flows and the Demographic Bonus”, Paris, 23-26 February 2004.

3. Tovel, H., Carmel, S. (2014). Maintaining Successful Aging: The Role of Coping Patterns and Resources. Journal of Happiness Studies, 15(2), 255–270.

4. Bowling, A., & Dieppe, P. (2005). What is successful ageing and who should define it? BMJ : British Medical Journal, 331(7531), 1548–1551.

5. Galiana, L., Gutiérrez, M., Sancho, P., Francisco, E.H., Tomás, J.M. (2016). Socio-Demographic Variables and Successful Aging of the Angolan Elderly. Scientifica (Cairo), 2016:5306756. doi: 10.1155/2016/5306756. Epub 2016 Mar 21. PubMed PMID: 27088039; PubMed Central PMCID: PMC4819103.

6. Canêdo, A.C., Lopes, C.S., Lourenço, R.A. (2018). Prevalence of and factors associated with successful aging in Brazilian older adults: Frailty in Brazilian older people Study (FIBRA RJ). Geriatr Gerontol Int, 18(8):1280-1285. doi: 10.1111/ggi.13334. Epub 2018 May 2. PubMed PMID: 29717801.

7. Dorji, N., Dunn, M. & Gurung, M. (2018). Socio-demographic correlates of psychological wellbeing among older adults in Bhutan. Environment and Social Psychology, 3(1), 1-8. doi: 10.18063/esp.v3i1.782

8. Heidari, S., Mohammadgholizadeh, L., Asadollahi, F& Abedini, Z. (2013). Assessment of health status of older adults in Ghom. The Journal of Ghom University of Medical Sciences, 7(4), 71-80.

9. Galiana, L., Gutiérrez, M., Sancho, P., Francisco, E. H., & Tomás, J. M. (2016). Socio-Demographic Variables and Successful Aging of the Angolan Elderly. Scientifica, 2016, 5306756. doi:10.1155/2016/5306756

10. Havighurst, R. J. (1963). Successful aging. In R. H. Williams, C. Tibbitts & W. Donahue (Eds.), Processes of aging. New York, NY: Atherton Press.

11. Rowe, J. W., & Kahn, R. L. (1997). Successful aging. Gerontologist, 37, 433–440.

12. Baltes, P. B., & Baltes, M. M. (1990). Psychological perspectives on successful aging: The model of selective optimization with compensation. In P. B. Baltes & M. M. Baltes (Eds.), Successful aging: Perspective from the behavioral sciences (pp. 1–34). New York, NY: Cambridge University Press.

13. Martin, P., Kelly, N., Kahana, B., Kahana, E., Willcox, B. J., Willcox, D. C. & Poon, L. W. (2015). Defining successful aging: A tangible or elusive concept? The Gerontologist, 55(1), 14–25.

14. Freund, A. M. (2008). Successful Aging as Management of Resources: The Role of Selection, Optimization, and Compensation. Research in Human Development, 5(2), 94–106.

15. Schmitt, A., Zacher, H., & Frese, M. (2012). The buffering effect of selection, optimization, and compensation strategy use on the relationship between problem solving demands and occupational wellbeing: A daily diary study. Journal of Occupational Health Psychology, 17(2), 139–149.

16. Freund, A. M. (2008). Successful Aging as Management of Resources: The Role of Selection, Optimization, and Compensation. Research in Human Development, 5(2), 94–106.

17. Baltes, P., B., Baltes, M., M., Freund, A., M., & Lang, F. (1999). The measurement of selection, optimization, and compensation (SOC) by self-report: Technical report. Berlin, Germany: Max Planck Institute for Human Development.

18. Aguilar-Vafaie, M., E., Shahi, H., & Besharat, M., A. (2016). Prediction of Successful Aging based on Life Management Strategies. Journal of Aging Psychology. 1(2):57-72.

19. Freund, A. M., & Baltes, P. B. (2002). Life-management strategies of selection, optimization, and compensation: Measurement by self-report and construct validity. Journal of Personality and Social Psychology, 82, 642–662.

20. Zanjari, N., Sharifian Sani, M., Hosseini Chavoshi, M., Rafiey, H. & Mohammadi Shahboulaghi, F. (2019). Research Paper: Development and Validation of Successful Aging Instrument. Iranian Rehabilitation Journal, 17(2), 129-140. Doi: http://dx.doi.org/10.32598/irj.17.2.129

21. Strawbridge, W. J., Wallhagen, M. I., & Cohen, R. D. (2002). Successful aging and well-being: Self-rated compared with Rowe and Kahn. Gerontologist, 42, 727–733. doi:10.1093/ geront/42.6.727

22. Freund, A. M., & Baltes, P. B. (1999). Selection, optimization, and compensation as strategies of life management: Correction to Freund and Bates (1998). Psychology and Aging, 14(4), 700-702.

23. Arias-Merino, E. D., Mendoza-Ruvalcaba, N. Ma., Arias-Merino, M. J., Cueva-Contreras, J. & Arias, C. V. (2012). Prevalence of Successful Aging in the Elderly in Western Mexico. Current Gerontology and Geriatrics Research, Article ID 460249, 6 pages doi:10.1155/2012/460249

24. Margolis, R. & Verdery, A. M. (2017). Older Adults without Close Kin in the United States. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 72(4), 688-693. doi: 10.1093/geronb/gbx068

25. Margelisch, K. Schneewind, K. A., Violette, J. & Perrig-Chiello, P. (2017). Marital stability, satisfaction and well-being in old age: variability and continuity in long-term continuously married older persons, Aging & Mental Health, 21(4), 389-398, DOI: 10.1080/13607863.2015.1102197

26. Stokes, J. E. (2016). Marital quality and loneliness in later life: A dyadic analysis of older married couples in Ireland. Journal of Social and Personal Relationships, 34(1), 114-135. https://doi.org/10.1177/0265407515626309

27. Kim, M. (2017). The Effect of Successful Aging on the Life Satisfaction of Korean Older Adults. Innovation in Aging, 1(1), 1068–1069, https://doi.org/10.1093/geroni/igx004.3910

28. Twenge, J. M., Campbell, W. K., and Foster, C. A. (2003). Parenthood and marital satisfaction: a meta-analytic review. J. Marr. Fam. 65, 574–583. doi: 10.1111/j.1741-3737.2003.00574.x

29. Onyishi, E. I., Sorokowski, P., Sorokowska, A., & Pipitone, R. N. (2012). Children and marital satisfaction in a non-Western sample: having more children increases marital satisfaction among the Igbo people of Nigeria. Evol. Hum. Behav. 33, 771–774. doi: 10.1016/j.evolhumbehav.2012.06.005

30. Sorokowski, P., Randall, A. K., Groyecka, A., Frackowiak, T., Cantarero, K., Hilpert, P. & Sorokowska, A. (2017). Marital Satisfaction, Sex, Age, Marriage Duration, Religion, Number of Children, Economic Status, Education, and Collectivistic Values: Data from 33 Countries. Frontiers in Psychology, 8, 1199. URL=https://www.frontiersin.org/article/10.3389/fpsyg.2017.01199. DOI=10.3389/fpsyg.2017.01199