DOI: https://doi.org/10.21203/rs.3.rs-1961070/v1
The proportion aged 60 years or older in the world's population is expected to double by 2050. In general, they have many complex diseases and poor oral health status. Oral health is one of the important health indicators of elderly people and it is affected by diverse factors, such as socioeconomic status. In this study, gender was considered as an associated factor that is closely related to edentulism. The sexual difference might be more influential within the geriatric population because of lower economic and educational backgrounds in that stage. Edentulism was significantly higher among elderly females than males, when combined with the education level. The lower the level of education, the higher the prevalence of edentulism as much as 24~28 times, especially in female (P=0.002). These findings suggest a more complex relationship between oral health, socioeconomic status, and gender.
According to the United Nation’s World Population Prospects 2019, the geriatric population aged 65 years or older is rapidly increasing and is expected to account for 16% of the world's population by 20501. These population experience problems with vision, hearing, and tooth loss with increasing age2 and has at least one restriction in activities of daily living (ADL), such as walking, eating, and washing3–5. According to the Health and Retirement Study (HRS) in the United States, almost one-fifth of the elderly with these restrictions answered that their health status was poor6. Older females have less access to health care and experience discrimination within the health care system7. In particular, the population from lower socioeconomic backgrounds was more likely to report limitations in daily living8. This makes the geriatric population more dependent on care. Because many complex diseases already existed, they got less attention for their lower priority, and it makes their oral health condition worse9. A decrease in the number of natural teeth makes usual life difficult and health status worse. Intaking of fibrous foods, fruits, and vegetables is decreasing and the risk of gastrointestinal disorders is increasing10,11. Tooth loss usually starts from the age of 40s and rapidly increases when in they were 60s or 70s12. According to the US National Health and Nutrition Examination Survey, edentulism was prevalent in 0.7% of the population aged 20–44 years but increased to 20.2% in the geriatric population aged over 65 years13. In South Korea, the population with no natural teeth was 0.2% when they were in their 40s and reached 13.6% at the age of 70s14.
Tooth loss is affected by various demographic and sociological factors. Studies suggest that the risk factors for edentulism included increasing age15,16, poor oral health practices, disability in function17,18, low socioeconomic status19, and living alone20. Elderly people suffer from health and oral health difficulties and the oral health gap to demographic social factors increasingly added and affects their overall life21. There are differences by sex in tooth loss as well, more frequently happening in females22. Supa et al mentioned that among males the major factor affecting edentulism was smoking; however, among females, it was lower socioeconomic status23. The elderly female showed a fifteen times higher economic dependence than males24 and these exacerbate oral health conditions and increase dissatisfaction, depression25, or inconvenience in their daily life of them26. Sexual differences in health among the elderly have been widely reported27–29 but they are not normally considered to be related to disparities, especially in oral health. There is a limited number of studies available to establish the relationship between the diverse variables related to these differences.
This study aimed to understand oral health disparities in the geriatric population, considering sexual difference as a related factor, through analysis of data obtained from the Korean National Health and Nutrition Survey (KNHANES Ⅶ, 2016 to 2018); our findings will aid in the proper planning and implementation of oral health policies.
1. General characteristics of the study population:
The total number of participants aged 65 years and older in the 7th National Health and Nutrition Survey (2016–2018) was 3,426. Among these elderly participants, 57.6% were female, which was 15% higher than the proportion of than male (Table 1). Most participants had only elementary school education or none (57.6%). Female had a graduation rate for elementary school, that was 1.5 times the graduation rate of male; however, the number of females graduating high school was only 0.5 times the number of male graduating high school. Twenty-one percent of the participants lived alone; twice as many females lived alone than male. With respect to morbidities, the proportion of the elderly population with hypertension and diabetes was 62.3% and 25.7%, respectively. Female showed a 5% higher rate of hypertension than male, but there was no significant difference in the prevalence of diabetes. The rate of drinking more than once a month was 34.4% and male were a three times higher rate than female. With respect to smoking, 15 times as many males reported a history of smoking than female. Almost 70% of subjects were involved in physical activity on a weekly basis with male reporting a higher likelihood of engaging in physical activity than female. Most people brushed more than twice a day (76.0%); 10% more female brushed more than twice a day than male. Only a quarter of the participants did an annual oral examination; more male received the examination than female.
2. Prevalence of edentulism in elderly individuals
The proportion of the geriatric population without teeth was 9.5%. This increased with age, with 18.1% of participants aged 80 years being edentulous; female showed a higher rate of edentulism than male (Table 2). With respect to educational level, the prevalence of edentulism was 11.1% in people finished elementary school, which was twice as high as that among high school graduates and those with a higher education. The difference of prevalence of edentulism by education level was 10 times higher in female than in male. The higher the income, the lower the prevalence of edentulism, especially in female; the gap between the first and fifth quartiles was almost double compared to male. The participants who lived alone had a slightly higher prevalence of edentulism than participants who lived with someone else. There was no statistical difference among participants with hypertension in general. However, female with this metabolic disease had a higher prevalence of edentulism. The participants who did not have a history of drinking monthly had a higher prevalence of edentulism, but there was no difference according to gender. The percent of the people with no teeth was 11.4% in smokers, which was higher than that in non-smokers, as much as twice in both male and female. In the case of physical activity, male who were not engaged in physical activity had a higher rate of edentulism. Participants, both male and female, who brushed lesser than twice a day had a five times higher likelihood of edentulism than those who brushed more. The rate of edentulism was almost five times higher in participants who did not receive oral examinations once a year; the gap was bigger in male, as ten times more likely to be edentulous.
3. Logistic regressions by risk factors associated with edentulism in elderly individuals
The logistic regression analysis for the factors affecting the prevalence of edentulism among elderly individuals is presented in Table 3. Age, educational level, income, living alone, and lifetime smoking were significantly associated with edentulism among elderly individuals. Participants who brushed fewer than twice a day were five times more likely to be edentulous than participants who did, and participants who did not receive yearly oral examinations were six times more likely to be edentulous than participants who did. After adjustment for all risk factors, the geriatric population who did not receive yearly oral examinations showed a lower odds ratio: almost four times that before. The coefficient of determination of NagelKerke R2 in this model was 0.185. In the third model considering the interaction between gender and education level, the odds ratio of edentulism decreased for females with the opposite results of those from the second model. Compared to the group of elderly female participants who graduated high school, people who finished middle school showed 29 times higher risk of being edentulous, and people who graduated elementary school were at a 24-fold higher risk of being edentulous. The lower the level of education, the higher the prevalence of edentulism, especially in females. The coefficient of determination of NagelKerke R2 in the final model was 0.198.
Variables |
Total |
Male |
Female |
p |
|||||
---|---|---|---|---|---|---|---|---|---|
N |
% |
n |
% |
n |
% |
||||
Total |
3,426 |
100.0 |
1,465 |
42.4 |
1,961 |
57.6 |
|||
Age |
|||||||||
65–69 |
1,059 |
31.5 |
482 |
33.0 |
577 |
30.4 |
0.483 |
||
70–74 |
916 |
27.4 |
387 |
27.4 |
529 |
27.4 |
|||
75–79 |
830 |
23.7 |
350 |
22.5 |
480 |
24.6 |
|||
≥ 80 |
621 |
17.4 |
246 |
17.1 |
375 |
17.6 |
|||
Educational level |
|||||||||
High school and more |
834 |
27.1 |
557 |
41.6 |
277 |
16.6 |
< 0.001 |
||
Middle school |
476 |
15.3 |
248 |
18.6 |
228 |
12.8 |
|||
Elementary school |
1,906 |
57.6 |
570 |
39.8 |
1,336 |
70.6 |
|||
Missing value |
210 |
90 |
120 |
||||||
Household income quintile |
|||||||||
1st |
700 |
21.1 |
300 |
20.9 |
400 |
21.3 |
0.944 |
||
2nd |
692 |
19.3 |
297 |
19.9 |
395 |
18.8 |
|||
3rd |
697 |
19.7 |
296 |
19.6 |
401 |
19.8 |
|||
4th |
673 |
20.4 |
286 |
20.4 |
387 |
20.4 |
|||
5th |
644 |
19.5 |
277 |
19.2 |
367 |
19.8 |
|||
Missing value |
20 |
9 |
11 |
||||||
Living status |
|||||||||
Alone |
853 |
21.0 |
201 |
11.7 |
652 |
27.8 |
< 0.001 |
||
With family |
2,573 |
79.0 |
1,264 |
88.3 |
1,309 |
72.2 |
|||
Location of residence |
|||||||||
Province |
1,852 |
53.8 |
762 |
52.5 |
1,090 |
54.7 |
0.203 |
||
Metropolitan |
1,574 |
46.2 |
703 |
47.5 |
871 |
45.3 |
|||
Hypertension |
|||||||||
Yes |
2,172 |
62.3 |
879 |
59.4 |
1,293 |
64.5 |
0.010 |
||
No |
1,248 |
37.7 |
585 |
40.6 |
663 |
35.5 |
|||
Missing value |
6 |
1 |
5 |
||||||
Diabetes |
|||||||||
Yes |
824 |
25.7 |
377 |
26.8 |
447 |
24.8 |
0.288 |
||
No |
2,239 |
74.3 |
955 |
73.2 |
1,284 |
75.2 |
|||
Missing value |
363 |
133 |
230 |
||||||
Drinking per month |
|||||||||
Once and more |
1,144 |
34.4 |
813 |
56.6 |
331 |
17.8 |
< 0.001 |
||
Never |
2,222 |
65.6 |
636 |
43.4 |
1,586 |
82.2 |
|||
Missing value |
60 |
16 |
44 |
||||||
Lifetime smoking |
|||||||||
Experienced |
1,216 |
35.8 |
1,116 |
77.0 |
100 |
5.1 |
< 0.001 |
||
Never |
2,146 |
64.2 |
330 |
23.0 |
1,816 |
94.9 |
|||
Missing value |
64 |
19 |
45 |
||||||
Aerobic physical activity* |
|||||||||
No |
2,268 |
69.0 |
904 |
64.1 |
1,364 |
72.7 |
< 0.001 |
||
Yes |
942 |
31.0 |
472 |
35.9 |
470 |
27.3 |
|||
Missing value |
216 |
89 |
127 |
||||||
Tooth brushing per day |
|||||||||
Less than twice |
840 |
24.0 |
449 |
30.3 |
391 |
19.4 |
< 0.001 |
||
Twice and more |
2,586 |
76.0 |
1,016 |
69.7 |
1,570 |
80.6 |
|||
Oral exam in last year |
|||||||||
No |
2,567 |
75.5 |
1,053 |
72.1 |
1,514 |
78.1 |
< 0.001 |
||
Yes |
795 |
24.5 |
393 |
27.9 |
402 |
21.9 |
|||
Missing value |
64 |
19 |
45 |
||||||
*Medium-intensity physical activity for more than 2 hours and 30 minutes, high-intensity physical activity for more than 1 hour and 15 minutes, or mixed intensity per week (1 minute of high-intensity physical activity is equal for 2 minutes of medium-intensity). |
Variables |
Total |
Male |
Female |
||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
N |
n |
% |
p |
N |
n |
% |
p |
N |
n |
% |
p |
||
Total |
3,426 |
328 |
9.5 |
0.597 |
1,465 |
138 |
9.1 |
1,961 |
190 |
9.8 |
|||
Age |
|||||||||||||
65–69 |
1,059 |
40 |
3.9 |
< 0.001 |
482 |
23 |
4.7 |
< 0.001 |
577 |
17 |
3.2 |
< 0.001 |
|
70–74 |
916 |
64 |
7.4 |
387 |
36 |
8.8 |
529 |
28 |
6.3 |
||||
75–79 |
830 |
110 |
13.1 |
350 |
43 |
12.7 |
480 |
67 |
13.3 |
||||
≥ 80 |
621 |
114 |
18.1 |
246 |
36 |
13.5 |
375 |
78 |
21.4 |
||||
Educational level |
|||||||||||||
High school and more |
834 |
49 |
5.1 |
< 0.001 |
557 |
44 |
7.2 |
0.126 |
277 |
5 |
1.2 |
< 0.001 |
|
Middle school |
476 |
33 |
6.8 |
248 |
21 |
8.2 |
228 |
12 |
5.2 |
||||
Elementary school |
1,906 |
208 |
11.1 |
570 |
64 |
11.2 |
1,336 |
144 |
11.0 |
||||
Household income quintile |
|||||||||||||
1st |
700 |
84 |
11.1 |
0.007 |
300 |
34 |
9.4 |
0.417 |
400 |
50 |
12.3 |
0.008 |
|
2nd |
692 |
77 |
11.8 |
297 |
33 |
11.7 |
395 |
44 |
11.9 |
||||
3rd |
697 |
71 |
11.0 |
396 |
28 |
9.6 |
401 |
43 |
12.0 |
||||
4th |
673 |
51 |
7.5 |
286 |
25 |
8.7 |
387 |
26 |
6.6 |
||||
5th |
644 |
42 |
6.1 |
277 |
18 |
6.4 |
367 |
24 |
5.9 |
||||
Living status |
|||||||||||||
Alone |
853 |
117 |
13.9 |
< 0.001 |
201 |
31 |
16.2 |
0.001 |
652 |
86 |
13.2 |
0.009 |
|
With family |
2,573 |
211 |
8.3 |
1,264 |
107 |
8.2 |
1,309 |
106 |
8.4 |
||||
Location of residence |
|||||||||||||
Province |
1,852 |
190 |
10.5 |
0.111 |
762 |
80 |
10.3 |
0.110 |
1,090 |
110 |
10.7 |
0.328 |
|
Metropolitan |
1,574 |
138 |
8.3 |
703 |
58 |
7.8 |
871 |
80 |
8.7 |
||||
High blood pressure |
|||||||||||||
Yes |
2,172 |
212 |
9.8 |
0.324 |
879 |
75 |
7.8 |
0.065 |
1,293 |
137 |
11.1 |
0.004 |
|
No |
1,248 |
113 |
8.8 |
585 |
63 |
11 |
663 |
50 |
6.9 |
||||
Diabetes |
|||||||||||||
Yes |
824 |
85 |
9.9 |
0.171 |
377 |
38 |
8.9 |
0.751 |
447 |
47 |
10.6 |
0.153 |
|
No |
2,239 |
183 |
8.0 |
955 |
82 |
8.3 |
1,294 |
101 |
7.7 |
||||
Drinking per month |
|||||||||||||
Once and more |
1,144 |
89 |
7.7 |
0.044 |
813 |
64 |
8.0 |
0.106 |
331 |
25 |
7.0 |
0.124 |
|
Never |
2,222 |
224 |
10.0 |
636 |
73 |
10.7 |
1,586 |
151 |
9.7 |
||||
Lifetime smoking |
|||||||||||||
Experienced |
1,216 |
139 |
11.4 |
0.008 |
1,116 |
123 |
10.7 |
< 0.001 |
100 |
16 |
19.5 |
0.008 |
|
Never |
2,146 |
174 |
8.0 |
330 |
14 |
4.1 |
1,816 |
160 |
8.7 |
||||
Aerobic physical activity* |
|||||||||||||
No |
2,268 |
224 |
9.8 |
0.105 |
904 |
89 |
10.4 |
0.011 |
1,364 |
135 |
9.4 |
0.479 |
|
Yes |
942 |
68 |
6.8 |
472 |
39 |
6.1 |
470 |
29 |
7.4 |
||||
Tooth brushing per day |
|||||||||||||
Less than twice |
840 |
181 |
21.7 |
< 0.001 |
449 |
85 |
19.2 |
< 0.001 |
391 |
96 |
24.6 |
< 0.001 |
|
Twice and more |
2,586 |
147 |
5.6 |
1,016 |
53 |
4.7 |
1,570 |
64 |
6.2 |
||||
Oral exam last year |
|||||||||||||
No |
2,567 |
295 |
11.6 |
< 0.001 |
1,053 |
130 |
12.2 |
< 0.001 |
1,514 |
165 |
11.1 |
< 0.001 |
|
Yes |
795 |
18 |
2.1 |
393 |
7 |
1.3 |
402 |
11 |
2.7 |
||||
*Medium-intensity physical activity for more than 2 hours and 30 minutes, high-intensity physical activity for more than 1 hour and 15 minutes, or mixed intensity per week (1 minute of high-intensity physical activity is equal for 2 minutes of medium-intensity). |
Variables |
No-interaction |
Interaction (Sex*Educational Level) |
||||||||
---|---|---|---|---|---|---|---|---|---|---|
Unadjusted |
Model 1 |
Model 2 |
||||||||
OR |
95% CI |
p |
OR |
95% CI |
p |
OR |
95% CI |
p |
||
Sex (= Male) |
||||||||||
Female |
1.079 |
0.813–1.433 |
0.597 |
1.507 |
0.740–3.071 |
0.258 |
0.074 |
0.010–0.576 |
0.013 |
|
Age (= 65–69) |
||||||||||
70–74 |
1.977 |
1.211–3.229 |
0.007 |
2.049 |
1.225–3.428 |
0.006 |
2.130 |
1.269–3.576 |
0.004 |
|
75–79 |
3.745 |
2.300-5.393 |
< 0.001 |
3.571 |
2.053–6.210 |
< 0.001 |
3.486 |
1.999–6.080 |
< 0.001 |
|
≥ 80 |
5.507 |
3.619–8.378 |
< 0.001 |
3.382 |
1.967–5.816 |
< 0.001 |
3.325 |
1.935–5.713 |
< 0.001 |
|
Educational level (= High school and more) |
||||||||||
Middle school |
1.364 |
0.817–2.276 |
0.234 |
1.440 |
0.809–2.563 |
0.215 |
0.908 |
0.465–1.773 |
0.777 |
|
Elementary school |
2.337 |
1.592–3.430 |
< 0.001 |
1.453 |
0.901–2.342 |
0.125 |
0.936 |
0.524–1.673 |
0.824 |
|
Household income (= 5th) |
||||||||||
4th |
1.249 |
0.766–2.037 |
0.371 |
1.168 |
0.660–2.065 |
0.594 |
1.121 |
0.634–1.981 |
0.694 |
|
3rd |
1.914 |
1.148–3.191 |
0.013 |
1.247 |
0.631–2.462 |
0.525 |
1.198 |
0.613–2.342 |
0.598 |
|
2nd |
2.074 |
1.310–3.283 |
0.002 |
1.036 |
0.561–1.914 |
0.909 |
1.015 |
0.554–1.859 |
0.961 |
|
1st |
1.935 |
1.222–3.064 |
0.005 |
0.880 |
0.437–1.711 |
0.719 |
0.852 |
0.428–1.697 |
0.649 |
|
Living status (= With family) |
||||||||||
Alone |
1.791 |
1.332–2.407 |
< 0.001 |
1.502 |
0.936–2.409 |
0.092 |
1.508 |
0.936–2.432 |
0.091 |
|
Location of residence (= Metropolitan ) |
||||||||||
Province |
1.304 |
0.940–1.808 |
0.111 |
1.202 |
0.825–1.751 |
0.336 |
1.227 |
0.841–1.790 |
0.288 |
|
High blood pressure (= No) |
||||||||||
Yes |
1.133 |
0.884–1.453 |
0.324 |
0.858 |
0.638–1.153 |
0.310 |
0.875 |
0.651–1.175 |
0.373 |
|
Diabetes (= No) |
||||||||||
Yes |
1.259 |
0.905–1.751 |
0.172 |
1.008 |
0.705–1.441 |
0.966 |
1.006 |
0.706–1.433 |
0.976 |
|
Drinking per month (= Never) |
||||||||||
Once and more |
0.749 |
0.565–0.992 |
0.749 |
0.854 |
0.526–1.081 |
0.124 |
0.748 |
0.523–1.071 |
0.113 |
|
Lifetime smoking (= Never) |
||||||||||
Experienced |
1.481 |
1.139–1.927 |
0.003 |
2.403 |
1.295–4.460 |
0.006 |
2.346 |
1.268–4.341 |
0.007 |
|
Aerobic physical activity* (= Yes) |
||||||||||
No |
1.483 |
0.919–2.393 |
0.107 |
0.922 |
0.563–1.509 |
0.746 |
0.920 |
0.562–1.506 |
0.739 |
|
Tooth brushing per day (= Twice and more) |
||||||||||
Less than twice |
4.672 |
3.501–6.235 |
< 0.001 |
3.471 |
2.502–4.815 |
< 0.001 |
3.548 |
2.559–4.919 |
< 0.001 |
|
Oral exam in last year (= Yes) |
||||||||||
No |
6.222 |
3.657–10.586 |
< 0.001 |
3.807 |
2.071–6.995 |
< 0.001 |
3.743 |
2.040–6.868 |
< 0.001 |
|
Gender*educational level (= Female*high school and more) |
||||||||||
Female*middle school |
28.877 |
3.488–238.080 |
0.002 |
|||||||
Female*elementary school |
24.422 |
3.272-182.275 |
0.002 |
|||||||
NagelKerke R2 |
0.185 |
0.198 |
||||||||
*Model 1: fully adjusted for gender, age group, educational level, household income quintile, living status with family, location of residence, existence of high blood pressure or diabetes, drinking, smoking, physical activity, frequency of tooth brushing, and oral exam experience in last year, Model 2: Model 1 plus interaction between gender and educational level |
The proportion of the world's population aged 60 years or older is expected to double by 2050. As a result, population aging is recognized as an important problem worldwide30. Oral health is an essential health indicator among elderly people9,10. A gap is reported in the oral health of geriatrics for various factors including socioeconomic and behavioral factors. In this study, gender was considered the main factor that affected the prevalence of edentulism among those aged 65 years or above.
There was no difference in the prevalence of edentulism according to gender until the interaction between gender and education level was considered, which was significant. Edentulism among elderly females was significantly higher than that among males when categorized by education level. The prevalence of edentulism among middle school or elementary school graduates and participants with lower education levels was 24–28 times that of high school graduates or participants with higher education in an elderly female. The prevalence of edentulism among elderly individuals in South Korea was 9.5%, which was lower than the prevalence of 12.9% observed in the United States31, but higher than the prevalence of 8.1% observed in Japan32. The proportion of elderly individuals is expected to reach 46.5% in 206733, of which the proportion of female elderly individuals is expected to be about 55%, higher than that of male elderly individuals in Korea. Gender may be an important factor associated with edentulism among the geriatric population, especially for economic and educational backgrounds. Some studies have reported that the lower the education or income, the higher the prevalence of edentulism34–37. This population is also reported to have lower subjective oral health, which might affect care for oral health38. Most of them showed a lower tendency to visit dental clinics39, which might have worsened oral health conditions. There was a significant difference in edentulism by socioeconomic level in an elderly female. This is the reason that the interaction between gender and socioeconomic factors is assumed to exist. There might be a more complex relationship between oral health, socioeconomic status, and gender. Among the geriatric Korean population, a female had a significantly less chance than a male of being educated. They also lived longer than males and many of them lived alone40. Elderly females were found to be more sensitive to socio-economic factors as well. The gap in economic poverty appeared in poorer elderly females, which worsened oral health41. Paola et al reported that elderly females did more preventive oral care than males, but complex mechanisms working in oral health make necessary careful management42. The oral health gender gap should be considered not just gender itself but also the contextual mechanism around it.
Regular tooth brushing twice a day and yearly oral examination was found to have effects on edentulism. Healthy behaviors were reported as closely related to oral health43. The prevalence of edentulism was higher in participants with a history of smoking, brushing fewer than twice a day, and not taking yearly oral examinations44,45. These oral health behaviors showed different patterns depending on gender, and females are known to visit the dentist more frequently, perform better oral care46, and have better knowledge, attitude, and behavior about oral health than male47,48. The elderly female showed about a 10% higher rate of brushing their teeth twice or more a day than males in this study. Likewise, each gender in elderly individuals had significant associations with different oral health behavior factors, such as physical activity for males and hypertension for females. The type of residence also showed a significant association. Elderly individuals living alone were at an almost two times higher risk of edentulism. Kim et al reported that elderly people who lived alone had a higher possibility of needing dentures and experiencing difficulty in mastication than geriatric people living with their families49. Elderly males living without families showed a higher level of edentulism. Elderly individuals living alone might have fewer opportunities to acquire and exchange information about oral health and more difficulties in practicing healthy oral behavior50.
There are several limitations of this study. First, social relationships and support might influence physical, mental, and oral health and behavior, especially in geriatric people51,52. The data used in this study did not include social capital variables such as the number of friends and meetings. It is necessary to understand the social relationship of elderly individuals with oral health in depth in the future. Second, it is difficult to identify the causal relationship because the data as this was a cross-sectional study. The present education or income levels were surveyed but the past socioeconomic status or oral health behavior of the participant could not be included in this survey. The causal relationship from previous conditions would be important in the study of the geriatric population. Future studies must design a longitudinal data set such as a cohort framework to identify the influential relationship after identifying the related factors. Even with these limitations, this study established the fundamentally important health characteristics of an aging society according to gender with oral health status using national representative data.
This study revealed the association between gender and socioeconomic factors related to the oral health of elderly individuals. In edentulism in elderly individuals, there was no difference according to gender, initially. After considering the interaction between gender and education, an elderly female had a lower possibility of being edentulous than a male. The prevalence of edentulism in the elderly female who graduated middle school or elementary school was 24 ~ 28 times that of high school graduates. Each gender of the geriatric population had significant associations with different oral health behavior factors, such as physical activity for males and hypertension for females. In conclusion, in the plan for oral health improvement in elderly individuals, gender characteristics must be identified, such as socioeconomic factors for females and health behavior factors for males.
Study Subjects. This study analyzed oral health conditions by gender in the geriatric population aged 65 years or older using the Korean National Health and Nutrition Survey (KNHANES Ⅶ, 2016-2018) data. The sampling frame was layered based on the size of the area (cities, provinces, and districts) and housing types (general housing, apartments). The ratio of residential area and educational background of household owners was used as the intrinsic stratification criteria. Finally, 576 districts were surveyed over 3 years, with 10,611 households participating in the study. A cohort of 24,269 participants was recruited with a response rate of 76.6%. Among them, 3,426 people were elderly, which was 21.0% of all subjects.
Study Variable. The general characteristics of the study sample were gender, age, education or income level, household type, region, comorbidities such as hypertension or diabetes, health-related behavior such as drinking, smoking, aerobic physical activity, brushing teeth, or visiting a dental clinic for oral examination per year. The independent variables are classified as shown in Table 1. The type of household was categorized by the number of family members - one as living alone and two or more as family living together. A person involved in as much as medium intensity physical activity for 2 h and 30 min, high-intensity physical activity for 1 h and 15 min, or medium and high-intensity physical activity per week (1-min-high intensity for 2 min) was defined as properly engaging in physical activity.
Statistical Analysis: A complex sample analysis was used because the KNHANES was a two-stage stratified cluster sampling. It was conducted by generating an integrated weight based on the prepared analysis plan file. The plan file adapted analysis weight with “oral examination weight”, design of the strata with “variance estimation” and “group aged 65 years or above, and cluster as primary sampling unit with the district. Complex sample frequency and chi-square tests were conducted to find out the difference in the prevalence of edentulism according to socioeconomic factors, chronic diseases, and health-related behaviors. A complex sample logistical regressions were performed with an unadjusted model with univariate variables, a fully adjusted model including all variables (Model 1), and an advanced model with interaction by gender and education (Model 2). All analyses used SPSS (Statistical Packages for Social Science 26.0. SPSS Inc., USA) and statistical significance was set to α=0.05.
Ethical approval and informed consent
This study used the dataset obtained from the KNHANES Ⅶ, 2016 to 2018. All KNHANES were conducted with participants’ informed consent after approval by the Research Ethics Review Committee of the Korea Disease Control and Prevention Agency (KDCA) (IRB No. 2018-03-P-A for the KNHANES VII). This analytical study was approved again by the institutional review board (IRB) of Kyung Hee University (IRB No. KHSIRB-21-337(EA)) as exemption of the review because this retrospective analysis included the dataset of national surveillance and did not contain personally identifiable information. All methods were carried out following the KNHANES analytic guidelines and regulations.
Data availability
The data that supports the findings of this study is available from the KDCA, but restrictions apply to the availability of data, which was used with permission for the current study and therefore not publicly available. Data is however available upon reasonable request and with permission of KDCA.
Acknowledgements:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2021R1F1A1063105).
Author Contributions
H.A.P. and J.I.R contributed for the conception and design of the work and wrote the main manuscript text; S.H.S has substantial contributions to the acquisition, analysis, and interpretation of data. All authors reviewed the manuscript.
Competing Interests:
The authors declare no competing interests.
Additional information
Correspondence and requests for materials should be addressed to J.I.R