The Association Between Health-related Quality of Life and Physical Activity in Postmenopausal Korean Women: Findings From the Korea National Health and Nutrition Examination Survey

DOI: https://doi.org/10.21203/rs.3.rs-225638/v1

Abstract

Background: Physical activity (PA) in postmenopausal women provides some relief of menopausal symptoms and improves health-related quality of life (HRQoL). This study used a cross-sectional database to investigate the association between PA level and HRQoL in postmenopausal Korean women.

Methods: This study investigated 8,122 postmenopausal women who participated in the Korea National Health and Nutrition Examination Survey VI to VII (2014–2018). Global Physical Activity Questionnaire (GPAQ) and Euro quality of life-5 dimensions (EQ-5D) questionnaire were used to collect data about the participants’ PA level and HRQoL. The adjusted Odds ratios (aORs) with 95% confidence intervals (95% CIs) for each dimensional problem of EQ-5D were derived using multi-variable logistic regression. Mean EQ-5D index scores were compared according to PA level groups.

Results: The aORs of each dimension of HRQoL of low PA group versus moderate PA group were 0.67 (95% CI 0.57–0.78) for mobility, 0.71 (95% CI 0.55–0.92) for self-care, 0.64 (95% CI 0.53–0.78) for daily activities, and 0.75 (95% CI 0.66–0.86) for pain/discomfort. Mean EQ–5D scores of the moderate PA (0.927 ± 0.120 vs. 0.884 ± 0.163, P < 0.001) and high PA (0.913 ± 0.144 vs. 0.884 ± 0.163, P = 0.023) groups were significantly higher than that of the low PA group.

Conclusions: PA level was found to be associated with better HRQoL among postmenopausal Korean women. This was especially significant in participants who were participating with a moderate level of PA. Additional studies are needed to analyze the persistence and long-term effects of PA on HRQoL.

Background

Starting from the mid-forties, most women reach perimenopause and postmenopause as the female sex hormone decreases, causing physical or psychological discomfort [1]. Consequently, various symptoms including anxiety, depression, headache, fatigue, joint pain, and weight gain start appearing [2]. Vasomotor symptoms, such as hot flushes, are one of the most common complaints occurring in about 75% of women during their transition [35] to menopause. These vasomotor symptoms, which are closely linked to tension, depression, sleeplessness, and general helplessness, have been notably observed to affect the psychological status and result in a decrease in the quality of life [69] .

Hormone replacement treatment (HRT) is currently the most effective treatment for vasomotor and genitourinary syndromes in postmenopausal women. However, a limitation of HRT is that it needs to consider individual differences, treatment goals, age, among other things, in order to maximize effectiveness and safety [10]. Since previous research has suggested that PA could help prevent postmenopausal symptoms [11], exercise has become increasingly utilized for the prevention and treatment of the symptoms. It is now becoming more widely accepted as a significant factor in improving the quality of life of these women. Earlier findings have also supported the usefulness of exercise in improving physical ability and mental stability [12]. Furthermore, previous studies have demonstrated that those who performed regular PA had better HRQoL than those who did not [13].

A few studies have reported the positive effects of PA on the quality of life in postmenopausal women. For example, the recommended levels of PA significantly improved upon symptom relief and quality of life in postmenopausal women regardless of hormone replacement therapy [1416]. Previous studies had simply analyzed these effects in terms of the presence or absence of simple PA and its effect at a certain level. Furthermore, only few studies have compared the quality of life by classifying PA according to intensity levels. Therefore, this study aimed to examine differences in the quality of life in relation to the level of PA in postmenopausal women included in the Korea National Health and Nutrition Examination Survey.

Methods

Study population and data collection

The study was conducted using data extracted from the sixth and seventh Korea National Health and Nutrition Examination Survey (KNHANES VI-VII), which is a nationwide project that investigated Korea’s civilian population. KNHANES VI-VII was conducted by the Ministry of Health and Welfare of Korea and the Korea Disease Control and Prevention Agency (KDCA) from 2014 to 2018 and included surveys of health and nutrition. The selection of households and participants for KNHANES VI-VII used a complex, multi-stage, probability-sampling design, allowing the production of nationally representative data. The KNHANES was approved by the institutional review board of KDCA (registration number: 2013-12EXP-03-5C). Written informed consent forms were obtained from the participants. Among 8,122 postmenopausal women who participated in the KNHANES VI–VII, 17 participants who did not have data on HRQoL and subjective health status and 58 participants who had no data regarding their PA were excluded. The selection process for the study population is shown in Fig. 1.

Research method

Physical activity (PA) level

The PA level of the participants has been classified by the Global Physical Activity Questionnaire (GPAQ) criteria developed by the World Health Organization [17]. In these criteria, a high intensity activity was defined as vigorous PA that caused tachypnea and tachycardia. Moderate intensity activity was defined as an average level of PA that caused a mild increase in breathing and heart rate. The PA was based on a self-report questionnaire that contained the number of days the participants performed physical activities in a week and the corresponding minutes of PA per day. The questionnaire results were converted into the metabolic equivalent of task minutes per week (METs). High intensity activity, moderate intensity activity, and walking were converted to 8.0, 4.0, and 4.0 METs. The participants were then assigned to either the low PA group (less than 600 MET min− 1), moderate PA group (601–2999 MET min− 1), or high PA group (higher than 3000 MET min− 1) according to the corresponding levels per week [17].

HRQoL and perceived health status

The KNHANES uses the Korean version of the European quality of life scale-5 dimensions (EQ-5D) questionnaire to assess HRQoL. The EQ-5D consists of five dimensions of the current health status, including mobility, self-care, daily activities, pain/discomfort, and anxiety/depression. The degree of each dimensional status was rated as “no problem exists,” “slight problems exist,” or “extreme problems exist.” This study used the Korean version of the weighted model of the EQ-5D for its analysis. The reliability and validity of the Korean version of the EQ-5D were evaluated and verified by a previous study on the general population, and the reliability level was observed to be moderate (Cohen kappa 0.32–0.64). In addition to the questionnaire with five dimensions, the EQ-5D index score was also used to produce a single index value that indicated overall health status. In this study, the researchers used the EQ-5D index score, which was calculated and validated by previous studies using the corresponding estimated weighted quality value for Koreans [18]. The perceived health status was inferred based on the following question: “How would you describe your overall health status?” (“very good,” “good,” “fair,” “poor,” and “very poor”). The responses “very good,” “good,” and “fair” were considered to indicate “not poor,” while “poor” and “very poor” were considered to indicate “poor.”

Covariates: sociodemographic information, health status, health behavior

Sociodemographic variables (age, marital status, level of education, place of residence, and household income) were collected using a self-reported questionnaire. Age group (below 50, 50 ~ 59, 60 ~ 69, and over 70 years of age), marital status, education (elementary school or lower, middle school, high school, technical college, and college or higher), household income (first, second, third, or fourth quartile), and health behaviors (smoking and drinking) were used for the analysis. Regarding the health status, the depressive symptoms and associated diseases (hypertension, diabetes, dyslipidemia, thyroid and coronary artery disease, stroke, and cancer) that were collected using a self-report questionnaire were also used.

Statistics analysis

All participants were divided into three groups (low, moderate, and high PA levels). To compare the basic demographics, anthropometric characteristics, lifestyle factors, and the five dimensions of quality of life using the EQ-5D of the three groups, continuous variables were presented as estimated mean ± standard errors and subsequently compared using Student’s t-test, while the categorical variables were presented as unweighted numbers and estimated percentages and subsequently analyzed using the chi-squared (χ2) test.

Univariate and multivariate logistic regression analyses were performed to evaluate the association between PA and each dimensional status of quality of life. We modified the original three categories into two categories by combining the categories “some problems” and “extreme problems,” since the number of responses with “extreme problems” for each dimension was insufficient to perform acceptable analyses.

One-way analysis of variance was performed to compare differences in EQ-5D index scores for each group with low, moderate, and high PA plus additional classifications regarding age and body mass index.

We performed the estimation command svy in the statistical/data analysis program to take the sampling weight into account so that the results could represent the entire Korean population. P < 0.05 was considered to indicate statistical significance for all outcomes. All statistical analyses were performed using STATA version 14.0 (STATA Corp., College Station, TX, USA).

Results

Baseline characteristics of the study participants

Table 1 depicts the descriptive characteristics of the study’s participants stratified according to the PA levels. Among 8122 participants, 5762 women (70.94%) were assigned to the low PA group, 2148 women (26.45%) to the moderate PA group, and 212 people (2.61%) to the high PA group. The majority had normal body mass index (BMI), were married, lived in cities, were in the middle-third in terms of household income, did not smoke nor drink, and did not report depressive symptoms (Table 1). Among the sociodemographic profiles, health status, and health behaviors in different PA level groups, all factors were found to show significant differences, except for smoking and depression.

Table 1 Baseline characteristics of the study participants according to their physical activity level

Physical activity level

(MET min/wk*)

Low PA

Mod PA

High PA

P-value

Number of people

Proportion, N (%)

5762 (70.94)

2148 (26.45)

212 (2.61)

 

Age, years

< 50 years

50–59 years

60–69 years

≥ 70 years

 

144 (2.50)

1617 (28.06)

1841 (31.95)

2160 (37.49)

 

106 (4.93)

824 (38.36)

756 (35.20)

462 (21.51)

 

12 (5.66)

91 (42.92)

76 (35.85)

33 (15.57)

<0.001

BMI, kg/m2

Low (<18.5)

Normal (≥18.5, <25)

Obesity (≥25)

 

129 (69.35)

3380 (68.80)

2223 (74.37)

 

53 (28.49)

1385 (28.19)

707 (23.65)

 

4 (2.15)

148 (3.01)

59 (1.97)

<0.001

Marital status

Single

Married

Widowed/Divorced/Separated

 

54 (0.94)

3684 (63.97)

2021 (35.09)

 

26 (1.21)

1518 (70.70)

603 (28.09)

 

2 (0.94)

157 (74.06)

53 (25.00)

<0.001

Education

Elementary

Middle-high

University

 

3109 (54.02)

2081 (36.16)

565 (9.82)

 

814 (37.95) 1009 (47.04)

322 (15.01)

 

64 (30.33)

108 (51.18)

39 (18.48)

<0.001

Residence

Capital

Metropolitan

Town/city

1355 (23.52)

1025 (17.79)

3382 (58.69)

687 (31.98)

436 (20.30)

1025 (47.72)

67 (31.60)

50 (23.58)

95 (44.82)

 <0.001

Employment

Employed

Unemployed

 

2330 (40.47)

3428 (59.53)

 

982 (45.74)

1165 (54.26)

 

119 (56.13)

93 (43.87)

<0.001

Household income

Lowest third

Middle third

Highest third

 

2064 (36.00) 2631 (45.88)

1039 (18.12)

 

512 (23.91)

1072 (50.07)

557 (26.02)

 

51 (24.17)

112 (53.08)

48 (22.75)

<0.001

Smoking

Non-smoker

Smoker

Past smoker

 

5274 (92.62)

165 (2.90)

255 (4.48)

 

2004 (94.13)

50 (2.35)

75 (3.52)

 

199 (94.76)

5 (2.38)

 6 (2.86)

0.162

Alcohol use

Non-drinker

Drinker

 

4229 (74.14)

1475 (25.86)

 

1466 (68.76)

666 (31.24)

 

137 (65.24)

73 (34.76)

<0.001

Depression

No

Yes

 

5255 (91.20)

507 (8.80)

 

1982 (92.27)

166 (7.73)

 

190 (89.62)

22 (10.38)

0.200

Presence of §comorbidity

No (without any)

Yes (any)

 

1922 (33.36)

3840 (66.64)

 

863 (40.18)

1285 (59.82)

 

106 (50.00)

106 (50.00)

<0.001

Data are presented as a number (weighted %) for categorical variables. PA = physical activity, BMI = body mass index, kg/m2, *Metabolic equivalent task-minute per week based on the Global Physical Activity Questionnaire (GPAQ), §comorbidity: hypertension, diabetes mellitus, dyslipidemia, thyroid disease, stroke, coronary artery disease, stomach cancer, liver cancer, colon cancer, etc. P-values were obtained by chi-square test for categorical variables.

Comparison of HRQoL and perceived health status according to PA levels

Table 2 shows the distribution of the HRQoL, EQ-5D index scores, and perceived health status based on the level of PA. Significant differences were observed between the moderate and high PA groups and the low PA group in all five dimensions of EQ-5D: exercise ability, self-management, daily activities, pain/discomfort, and anxiety/depression. Furthermore, the mean EQ-5D scores of the moderate PA (0.927 ± 0.120 vs 0.884 ± 0.163, P < 0.001) and high PA (0.913 ± 0.144 vs 0.884 ± 0.163, P = 0.023) group were significantly higher than those of the low PA group (Table 2). Similarly, the perceived health conditions was associated with a significant difference in the proportion of negative answers between the low, moderate, and high PA groups.

Table 2. Comparison of the health-related quality of life and perceived health according to physical activity level

PA = physical activity, EQ-5D = European quality of life scale-5 dimensions. Data are presented as a number (weighted %) for categorical variables or as a mean ± standard error for continuous variables. P-values were obtained by chi-square test for categorical variables and by ANOVA analysis for the continuous variables, respectively.

Relationship between PA level and health-related quality of life (HRQoL)

Table 3 presents the odds ratios (ORs) and 95% confidence intervals (CIs) for poor HRQoL and perceived health status on all 5 EQ-5D dimensions (mobility, self-care, daily activities, pain/discomfort, and anxiety/depression) based on the PA as the independent variable. From the crude logistic analyses, a significant tendency for the cross-ratio regarding low quality of life to be reduced in the moderate and high PA group was confirmed in all five dimensions of EQ-5D as compared to that in the low PA group. Similarly, in the ORs for poorly-perceived health status, the moderate and high PA groups showed a reduced cross-ratio in comparison with the low PA group.

Table 3. Impaired health-related quality of life according to physical activity level

CI = confidence interval, PA = physical activity, EQ-5D = European quality of life scale-5 dimensions, OR = odds ratio, **Metabolic equivalent task-minute per week based on the Global Physical Activity Questionnaire(GPAQ), **Adjusted for BMI, age, marital status, education level, household income, employment status, residency, smoking, alcohol use, depression, and comorbidity.

Furthermore, we performed multivariate logistic regression analyses after adjusting for age, marital status, education level, place of residence, household income, smoking, drinking, depression, and comorbidities. The aORs of dimensional problems of HRQoL of the low PA group versus moderate PA group were 0.67 (95% CI 0.57–0.78) for mobility, 0.71 (95% CI 0.55–0.92) for self-care, 0.64 (95% CI 0.53–0.78) for daily activities, and 0.75 (95% CI 0.66–0.86) for pain/discomfort. In addition, in the perceived health condition, a significant tendency of decreased cross-ratios regarding poorly-perceived health condition in the low PA group was found as compared to the moderate and high PA groups. Further, the aOR for poorly-perceived health status in the moderate PA (aOR = 0.87, 95% CI 0.75–0.99) group was more decreased than those of the low PA group.

Differences in HRQoL according to age, body mass and level of PA

Figure 2 shows the EQ-5D index values according to the level of PA by age group (below 50, 50–59, 60–69, and over 70 years of age). Compared to the low PA group, the moderate PA group showed significantly higher EQ-5D index results in two age groups: 60–69 years of age (0.901 ± 0.137 vs 0.926 ± 0.119, P < 0.001), and over 70 years of age (0.819 ± 0.196 vs 0.870 ± 0.162, P < 0.001). Figure 3 shows the EQ-5D index values according to the level of PA in three groups: low, normal, and high body mass index (BMI). Compared to the low PA group, the moderate PA group had significantly higher EQ-5D index in the normal (0.899 ± 0.151 vs 0.936 ± 0.110, P < 0.001) and high BMI groups (0.863 ± 0.172 vs 0.908 ± 0.132, P < 0.001).

Discussion

The current findings suggest significant differences in the quality of life between the moderate and high PA groups and the low PA group in postmenopausal women; the EQ-5D index score also showed a significant difference. In particular, compared to the low PA group, the moderate PA group showed a significantly higher quality of life index in the age groups above 60 with normal or high BMI. Although a number of previous studies have reported the positive aspects of PA in postmenopausal women, no study has compared the quality of life according to the level of PA in large groups to the best of our knowledge. Therefore, this study was the first attempt in analyzing the HRQoL and perceived health status in different PA level groups involving 8,122 postmenopausal women who participated in the sixth and seventh edition of the National Health and Nutrition Survey (2014–2018).

Postmenopausal women may experience reduced quality of life due to physical, psychological, and social issues. In particular, PA subsequently decreases due to weight gain and decadence of the musculoskeletal system. However, it must be noted that PA level, along with the quality of life, can still be increased through regular and well-controlled exercise [19]. The current study also found significant differences between the moderate and high PA groups and the low PA group in all five dimensions of the quality of life, namely exercise ability, self-management, daily activities, pain/discomfort, and anxiety/depression on top of the EQ-5D index score. In particular, when compared to the low PA group, the moderate PA group showed significantly higher quality of life index in the age groups above 60 with normal and high BMI. This is consistent with the meta-analysis reported by Pucci GC et al. [20] who revealed a higher quality of life in the high PA level elderly groups when compared to low PA level elderly groups. Similarly, a positive correlation between elevated PA and high quality of life in groups with underlying diseases such as diabetes and cancer [21, 22] has been previously reported. Studies investigating the relationship between menopause and HRQoL in middle-aged women revealed that postmenopausal women had lower EQ-5D index values than pre-menopausal women, which suggests that the deterioration of physical function happening mostly within five years of menopause is a major factor for this difference [23]. However, according to a randomized control study by Moriyama CK et al.[15], a significant difference existed in the changes in physical function in the group with moderate PA levels regardless of undergoing hormone replacement therapy. Furthermore, PA was observed to improve the quality of life along with the alleviation of menopausal symptoms.

The effects of exercise and PA in postmenopausal women on their health outcomes have been reported in several studies; e.g., exercise can lower the risk of cardiovascular disease, prevent osteoporosis, and lower BMI and blood pressure [2427]. Exercise can also alleviate hot flushes and menopausal symptoms since PA has been attributed to increased blood beta-endorphins, which is known to decrease after menopause [28], resulting in the relief of vasomotor symptoms [29]. The current findings are also consistent with previous results. Furthermore, the current study found that moderate PA showed a more significant difference than high PA when compared to low PA. In previous studies investigating the level of PA and the quality of life, the group that performed moderate or high intensity (23METs/hour/week) PA levels showed significantly higher quality of life than those who did not [16]. Morimoto T, et al. notably reported that a higher PA level would lead to positive effects on the quality of life in both men and women and, in particular, the highest intensity of PA showed a significant difference in various dimensions of the quality of life in women [14].

The change in PA itself was not observed to have a direct relation to the alleviation of vasomotor or psychological symptoms [30]. However, the weight loss that resulted from increased PA was correlated with the alleviation of overall symptoms of menopause. Thus, it is believed that a moderate level of PA may have led to weight loss and an increased awareness of health levels, which could have influenced the results. In particular, in the comparative analysis of EQ-5D according to BMI, only the moderate PA group had a significant difference compared to low PA group in the normal and high BMI groups. This was not found in the low BMI group, which suggests that factors such as varying weight loss due to difference in PA levels may be related to the observed result. This study did not include analysis of the weight loss among the three comparison groups. Thus, further studies involving additional comparative analysis on this topic would be useful.

It has been previously reported that a clear association was found between menopausal symptoms, including vasomotor symptoms, and the resulting low quality of life [8]. Therefore, it can be inferred that the alleviation of menopausal symptoms with the increase in beta-endorphin levels through PA or weight loss improves the quality of life. Additionally, the psychological and social effects of PA, which improves the quality of life, should also be considered. The EQ-5D evaluation dimensions also reflect certain psychological and social factors, such as self-management and anxiety/depression. The corresponding factors resulting from the PA level, including social connectedness and reinforcement of self-esteem must also be considered. On the other hand, in the comparison by age groups, no significant difference according to the PA level in the age groups under 60 years of age was found. The researchers believe that the PA level in those groups produced a different effect on the quality of life because, unlike the age group over 60 years of age, the postmenopausal symptoms and durations differed depending on the duration after menopause.

Our study had several limitations. First, the cross-sectional study design prevented the explanation of the clear causal relationship between the level of PA and quality of life. Second, since the quantification of PA level was based on a self-report survey, it may be more or less inaccurate. In particular, recall bias could not be completely ruled out. Lastly, reflecting on the persistence of PA was difficult due to the analysis of the PA level being only conducted at the time of the survey. Analyzing the persistence and long-term effects of PA through subsequent studies is highly recommended. Despite these limitations, our study was more extensive than many previous studies, as this study used a nationally representative study population. Furthermore, a greater number of sociodemographic factors, including residence, household income, and marital status, were taken into account as opposed to previous studies. Finally, this was the first attempt to consider PA levels in comparing the quality of life in postmenopausal women.

Conclusion

This study confirmed that differences exist in HRQoL and perceived health status among the low, moderate, and high PA groups in postmenopausal Korean women. In particular, moderate PA was more efficient in improving the quality of life as compared to high PA. This suggests that PA may help women who suffer from postmenopausal symptoms and low quality of life by alleviating their symptoms and improving their quality of life. This approach is different from conventional hormone replacement therapy. In particular, the researchers believe that this study will become a useful guideline in improving the actual quality of life in postmenopausal women, especially in that it shared the concept as well as laid out concrete action plans involving moderate PA for the future.

Abbreviations

BMI, Body mass index

CI, Confidence intervals

GPAQ, Global Physical Activity Questionnaire

HRQoL, Health-related quality of life

HRT, Hormone replacement treatment

KNHANES, Korea National Health and Nutrition Examination Survey

OR, Odds ratios

PA, Physical activity

Declarations

Acknowledgements

Not applicable.

Authors’ contributions

Design of the study : H.K., J.P., B.O.

Data analysis and interpretation : H.K., J.P., Y.E.

Preparation of manuscript : J.P., H.K., K.M.

Review of final draft : S.L., H.H., J.K.

All authors read and approved the final manuscript. 

Funding

This work was supported by Korean Academy of Menopause and Andropause.

Availability of supporting data

The KNHANES database is publicly available at the KNHANES website (http://knhanes.cdc.go.kr). The datasets during and/or analyzed during the current study available from the corresponding author on reasonable request.

Ethical approval and consent to participate

The KNANES surveys (http://knhanes.cdc.go.kr/) are approved by the Institutional Review Board of KDCA (registration number: 2013-12EXP-03-5C). Written informed consent forms were obtained from the participants.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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