Effect of socioeconomic status on the physical and mental health of the elderly: the mediating effect of social participation | BMC Public Health

Characteristics of samples

Table 2 showed the demographic characteristics of the respondents. With respect to age group, there were 2402 (23.56%) respondents aged 75 or younger and 2826 (27.71%) were aged 95 or older. The proportion of each age group was relatively close. Of all the respondents, there were 4320 (42.37%) males and 5877 (57.63%) females. 4261 (41.79%) respondents married and living with spouse and the percentage of the respondents living alone (widowed or divorced) was 58.21%. More than 40% of the elderly lived in rural areas, and the number of elderly people living in city was 2606 (25.56%) and in town was 3297 (32.33%). More than half of the elderly came from eastern China. In terms of access to health services, 53.17% of the respondents lived within 1 km of the nearest health facility. However, there still had 1774 (17.40%) respondents lived more than 3 km of the nearest health facility. Most of the elderly people (87.69%) had medical insurance but only 29.37% of the respondents had pension insurance.

Table 2 The characteristics of sample (No.= 10.197)

As shown in Table 3, in terms of socioeconomic status, 3134 (30.73%) respondents had an annual income of less than 10,000 yuan, accounting for the highest proportion. Those with annual incomes of 10,000-30,000 yuan were the least, accounting for 18.84% of the respondents. The education level of respondents in the survey was generally low. 5040 (49.43%) respondents reported that they had never attended school and only 996 (9.77%) of them reached education level of senior and above. Among the three main occupational categories given, sample engage in agriculture accounted for 68.46%. Governmental or professional jobs accounted for the lowest percentage of respondents (19.04%). With respect to the social participation, the average score of the item ‘group exercise’ was 4.21 ± 1.97 and the item ‘organized social activities’ was 1.31 ± 0.87. The average score of the item ‘interact with friends’ was 4.14 ± 2.26. Finally, the health status of the respondents, the average score of IADL was 17.98 ± 6.32 and the average score of MMSE was 23.04 ± 8.52.

Table 3 Socioeconomic status, social participation and health status of sample

Results of mediation effect analysis

Omnibus mediation effect analysis

First, omnibus effect analysis was conducted. Based on the method proposed by Hayes [43], only when the omnibus total effect test, the omnibus direct effect test and the omnibus mediation effect test were significant, the next step of relative mediation effect analysis could be carried out. As shown in Table 4, with respect to the group exercise, when IADL was the dependent variable, the results of omnibus effect analysis with income or education as independent variables were significant. That was, when income was taken as the independent variable, F value in the omnibus total effect test was 4.94 (p= 0.01), indicating that at least one of the there relative total effects was not equal to 0. F value in the omnibus direct effect test was 2.90 (p<0.001), indicating that at least one of the there relative direct effects was not equal to 0. The bootstrap 95% CI of omnibus mediation effect test was (0.002,0.005), 0 was not included. Therefore, it was necessary to make further relative mediation effect analysis. When MMSE was the dependent variable, the omnibus mediation effect test of each independent variable with group exercise as the mediation variable was significant. In terms of the mediation variable 'interact with friends', Omnibus test was significant only when education was the independent variable, whether IADL or MMSE was the dependent variable. Finally, when organized social activities was the mediation variable, Except when occupation was the independent variable and IADL was the dependent variable, omnibus test of all variables was significant under other conditions. In addition, every control variable was included in all of the above tests.

Table 4 Omnibus effect analysis (F value)

Relative mediation effect of participating in group exercise

Based on the result of omnibus effect analysis, the test of relative total effect and relative mediation effect was conducted. As shown in Table 5, when IADL was the dependent variable, the variable group exercise has significant relative mediation effect at part of income and education levels on IADL. Specifically, compared with the very-low-income group, the elderly with high income (annual income ≥90,000 yuan) were more likely to improve their physical health by participating in group exercise. The relative mediation effect accounted for 64.11% (atheb = 0.24, 95% CI [0.17,0.3]). That was, 64.11% of the improvement in physical health among high-income people was mediated by participation in group exercise. Compared with illiteracy, the elderly with other education level could improve their health by participating in group exercise. The size of relative mediation effect increased when education level promoted. Among the elderly with education of senior and above, 56.30% (atheb = 0.62, 95% CI [0.52,0.73]) of the improvement in physical health was mediated by participating in group exercise. When MMSE was the dependent variable, the variable group exercise had significant relative mediation effect at part of income, education and occupation levels on MMSE. Group exercise mediated the improvement of mental health in medium-income and high-income groups. The proportion of relative mediation effect was up to 20.44% (atheb = 0.12, 95% CI [0.07,0.17]). Same to the effect on IADL, the size of relative mediation effect on mental health increased when education level promoted. In terms of occupation, compared with the elderly engaged in agriculture, participating in group exercise had a significant relative mediation effect on mental health improvement in both governmental & professional and commercial & service occupational groups. The proportion of relative mediation effect was 16.92% (atheb = 0.31, 95% CI [0.23,0.39]) and 28.74% (atheb = 0.19, 95% CI [0.13,0.25]), respectively.

Table 5 Relative mediation effect of the variable ‘group exercise’

Relative mediation effect of interacting with friends

In terms of the mediation variable ‘interact with friends’, the omnibus effect analysis indicated that the mediation effect on the improvement of health status was significant only when the independent variable was education. Referring to Table 6, compared with the elderly who didn’t have any educational experience, the elderly with the education level of primary or junior were more likely to improve the physical health status through interacting with friends. The proportion of relative mediation effect was 24.74% (atheb = 0.24, 95% CI [0.16,0.32]) and 33.72% (atheb = 0.29, 95% CI [0.16,0.44]), respectively. The relative mediation effect on improvement of physical health was not significant when education level was senior and above (atheb = 0.13, 95% CI [0,0.26]). When MMSE was the dependent variable, interacting with friends mediated health status among elderly with different levels of education. The proportion of relative mediation effect was up to 11.20% (atheb = 0.28, 95% CI [0.15,0.41]) with the education level of junior.

Table 6 Relative mediation effect of the variable ‘interact with friends’

Relative mediation effect of participating in organized social activities

As shown in Table 7, when IADL was the dependent variable, the variable organized social activities has significant relative mediation effect at part of income and education levels on IADL. Compared with the very-low-income group, the elderly with high annual income were more likely to have their physical health status improved by participating in organized social activities. The relative mediation effect accounted for 21.20% (atheb = 0.08, 95% CI [0.05,0.11]). In terms of education, compared with the elderly group of illiteracy, the elderly with the education level of senior and above were more likely to improve the physical health status through participating in organized social activities, the proportion of relative mediation effect was 21.20% (atheb = 0.33, 95% CI [0.26,0.4]).

Table 7 Relative mediation effect of the variable ‘organized social activities’

When MMSE was the dependent variable, there existed relative mediation effects at different levels of the three independent variables on MMSE. Specifically, organized social activities mediated the improvement of mental health in medium-income and high-income groups. The size of relative mediation effect accounted for 4.05% (atheb = 0.02, 95% CI [0.01,0.04]) and 4.92% (atheb = 0.06, 95% CI [0.03,0.09]), respectively. The elderly with education level of junior and above could improve their health by participating in organized social activities when compared with illiteracy. The proportion of relative mediation effect is up to 7.80% (atheb = 0.22, 95% CI [0.15,0.28]) with the education level of senior and above. Finally, compared with the elderly engaged in agriculture, the elderly engaged in governmental & professional or commercial & service occupational jobs were more likely to have their mental health status improved through some organized social activities. The relative mediation effect was 13.04% (atheb = 0.09, 95% CI [0.06,0.12]) in the commercial & service group and 9.16% (atheb = 0.17, 95% CI [0.12,0.22]) in the governmental & professional group.

Leave a Reply

Your email address will not be published.