JOGNN CNE Continuing Nursing Education (CNE) Credit A total of 1.4 contact hours may be earned as CNE credit for reading “Effects of the Body Mass Index on Menopausal Symptoms Among Asian American Midlife Women Using Two Different Classification Systems” and for completing an online posttest and evaluation. AWHONN is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center’s Commission on Accreditation. AWHONN holds a California BRN number, California CNE Provider #CEP580
IN FOCUS
Effects of the Body Mass Index on Menopausal Symptoms Among Asian American Midlife Women Using Two Different Classification Systems Sun Ju Chang, Wonshik Chee, and Eun-Ok Im
ABSTRACT Objective: To explore the effects of the body mass index (BMI) on menopausal symptoms among Asian American midlife women using two different classification systems: the international classification and the BMI classification for public health action among Asian populations.
http://JournalsCNE.awhonn.org
Design: Secondary analysis using data from two large Internet survey studies. Setting: Communities and groups of midlife women on the Internet. Keywords Asian American midlife body mass index menopause symptoms
Participants: A total of 223 Asian American midlife women who were recruited over the Internet. Methods: The Midlife Women’s Symptom Index and self-reports of height and weight were used to collect data. The data were analyzed using multiple analyses of covariance. Results: No significant differences in the prevalence and severity scores among three subscales and total menopausal symptoms according to the international classification were found. When the BMI classification for public health action among Asian populations was used as an independent variable, significant differences were found in the severity scores of three subscales and total menopausal symptoms. Results of the post-hoc analyses showed that Asian American midlife women who were in the BMI classification for high risk had significantly more severe menopausal symptoms than those who were in the BMI classification for increased risk. Conclusion: For Asian American women, BMI categorized using the BMI classification for Asian populations is more closely related to the severity of menopausal symptoms than BMI categorized using the international classification. Nurses need to consider the BMI classification for Asian populations when they develop interventions to prevent and alleviate menopausal symptoms among Asian American midlife women.
JOGNN, 43, 84-96; 2014. DOI: 10.1111/1552-6909.12261 Accepted May 2013
Correspondence Sun Ju Chang, PhD, School of Nursing University of Pennsylvania 418 Curie Blvd, Philadelphia, PA 19104. [email protected]
Sun Ju Chang, PhD, is a postdoctoral researcher in the School of Nursing, University of Pennsylvania, Philadelphia, PA.
(Continued)
84
enopause constitutes the permanent cessation of a woman’s menstrual periods due to the discontinuance of hormone production in the ovaries (U.S. Department of Health and Human Services, Office of Women’s Health, 2010). According to the National Institute of Aging (2008), the mean age of menopause is 51, although it varies depending on a woman’s lifestyle (e.g., smoking habits) and medical history (e.g., hysterectomy). However, with changes in the levels of hormones, including estrogen and progesterone, a woman in her forties might undergo menopausal transition or perimenopause (American Society for Reproductive Medicine, 2012; National Institute of Aging, 2008). The period after menopause
M
is known as postmenopause (American Society for Reproductive Medicine, 2012; National Institute of Aging, 2008). Throughout the menopause process, midlife women between age 40 and 60 might experience various menopausal symptoms, including physical symptoms (e.g., hot flashes, night sweats, vaginal dryness, stiffness and soreness in the joints and muscles), psychological symptoms (e.g., forgetfulness, difficulty falling or staying asleep, depressed mood), and psychosomatic symptoms (e.g., dizziness, fatigue, headache) (Im, 2006). Because these symptoms can affect a woman’s quality of life, health, and well-being (Daley et al., 2007; Waidyasekera, Wijewardena, Lindmark, & Naessen, 2009), health
C 2013 AWHONN, the Association of Women’s Health, Obstetric and Neonatal Nurses
http://jognn.awhonn.org
IN FOCUS
Chang, S. J., Chee, W., and Im, E.-O.
CNE http://JournalsCNE.awhonn.org
care providers and researchers have devoted considerable attention to identifying risk factors for the development and aggravation of menopausal symptoms. With regard to risk factors for the development and aggravation of menopausal symptoms, previous researchers have reported several factors, including menopausal stage, age, education, body mass index (BMI), smoking, diet, physical activity, and alcohol use (Gold et al., 2006; Perez, Garcia, Palacios, & Perez, 2009). Among these factors, the BMI, which is related not only to menopause age and menopausal symptoms but also to metabolic syndrome and cardiovascular disease after menopause, is considered an important factor in many menopausal symptomsrelated studies because the BMI has the potential to be modified through interventions (Carr, 2003; Fernandez-Alonso et al., 2010; Morris et al., 2012). In the current literature, researchers have reported a positive association between BMI and menopausal symptoms among multiethnic groups of midlife women, including White, African American, and Hispanic (Fernandez-Alonso et al., 2010; Im, Lee, Chee, Brown, & Dormire, 2010; Lu, Liu, & Eden, 2007). However, the association between BMI and menopausal symptoms among Asian American midlife women who experience menopausal symptoms has not been demonstrated in the current literature (Gold et al., 2006; Im et al., 2010). A plausible reason might be the differences in body composition between Asian populations and Western populations. Many Asian populations, even Asian Americans, have a higher percentage of body fat than Western populations who are at the same BMI (Lauderdale & Rathouz, 2000; World Health Organization [WHO], 2004). For this reason, an alternative BMI classification for public health action among Asian populations that reflects Asian-specific body composition has been introduced in health sciences (WHO, 2004). However, virtually none of the studies on Asian American midlife women has been conducted using the alternative BMI classification for public health action among Asian populations. Also virtually no researchers have explored whether the alternative BMI classification for public health action among Asian populations would be more appropriate for Asian American midlife women than the current BMI classification. To design and develop adequate interventions for preventing and alleviating Asian American midlife women’s menopausal symptoms, the effects of the
JOGNN 2014; Vol. 43, Issue 1
The Body Mass Index Classification introduced by the World Health Organization for public health action among Asian populations reflects Asian-specific body composition.
BMI on menopausal symptoms need to be investigated while considering Asian-specific body composition. Hence, the purpose of the secondary analysis was to explore the effects of the BMI on menopausal symptoms among Asian American midlife women by using two different classification systems. For this purpose, we began with a review of two BMI classification systems, the international classification (current classification) and the BMI classification for public health action among Asian populations. Then we reviewed the associations between BMI and menopausal symptoms in light of the existing hypotheses, including the thin hypothesis and the thermoregulatory model. Finally, the effects of the BMI on the prevalence and severity of menopausal symptoms among Asian American midlife women were examined under the two different classification systems using the findings from a secondary analysis.
Background Body Mass Index and Classification Systems Body mass index is calculated as a person’s weight (in kilograms) divided by his or her height squared (in meters) (kg/m2 ). By comparing a person’s weight to height, BMI can be used to indirectly measure a person’s body fat (Vasudevan, Stotts, Anabor, & Mandayam, 2012; WHO, 2004). Body mass index is not a diagnostic measurement. However, because BMI can easily be used to assess overweight and obesity among the general population and has been reported to be a reliable indicator of obesity-related diseases such as type 2 diabetes and coronary heart disease, it is widely used in the health care field worldwide (Centers for Disease Control and Prevention [CDC], 2011; Chiu, Austin, Manuel, Shah, & Tu, 2011; Vasudevan et al.; WHO, 2004). For interpretation of BMI, BMI cutoff points with international classification of weight status for adults were introduced by the WHO) (1995, 2000) (see Table 1). These BMI cutoff points and the international classification have been widely accepted for international use as screening measurements to identify individuals at high risk for obesity-related diseases (CDC, 2011; WHO, 2004). However, because these BMI cutoff points were based on
Wonshik Chee, PhD, is an associate professor in the School of Nursing, University of Pennsylvania, Philadelphia, PA Eun-Ok Im, PhD, MPH, RN, CNS, FAAN, is the Marjorie O. Rendell Endowed Professor in the School of Nursing, University of Pennsylvania, Philadelphia, PA
85
IN FOCUS
Effects of the Body Mass Index on Menopausal Symptoms
CNE http://JournalsCNE.awhonn.org
Western populations, they might not be sensitive to detection of potential risk in other populations (Rush, Freitas, & Plank, 2009). For example, Asian populations have a higher body fat percentage at a lower BMI value and a higher risk of diabetes, heart disease, and even death than Western populations at the same BMI (Lewis et al., 2009; WHO, 2004). These tendencies have been observed in Asian immigrant populations as well. For example, in a study in New Zealand, Asian Indians at BMI values ranging from 24 to 26 kg/m2 had the same body fat percentage as Europeans at a BMI value of 30 kg/m2 (Rush et al., 2009). Also, in a study among Asian Americans, the prevalence of metabolic syndrome of Asian Americans at BMI values ranging from 19.6 to 19.9 kg/m2 was comparable to that of non-Hispanic Whites at a BMI value of 25 kg/m2 (Palaniappan, Wong, Shin, Fortmann, & Lauderdale, 2011). Researchers assessing diabetes risk using ethnic-specific cutoff points also found that BMI values of Chinese and South Asians who lived in Canada and developed diabetes were lower than those of Whites (Chiu et al., 2011). For these reasons, researchers and health care providers have suggested the need for Asian-specific BMI cutoff points that can be used to effectively screen overweight and obese individuals among Asian populations. In 2004, the WHO reported that the BMI values indicating high risk for type 2 diabetes and cardiovascular disease in Asian populations were lower than the current WHO cutoff points for being overweight. However, the WHO suggested an alternative BMI classification for public health action among Asian populations (see Table 1). This alternative BMI classification was proposed instead of redefining BMI cutoff points for Asian populations due to the necessity for a standardized approach around the world and a lack of available data for clear BMI cutoff points for Asian populations. Although new BMI cutoff points for Asian populations have been suggested in some studies (Gu et al., 2006; Pan et al., 2004; Stevens & Nowicki, 2003; Wen et al., 2009), no consensus has been reached in terms of clear points for this population. Hence, this study used the BMI classification for public health action among Asian populations as suggested by the WHO.
Body Mass Index and Menopausal Symptoms Current literature has reported the associations between BMI and menopausal symptoms, es-
86
JOGNN, 43, 84-96; 2014. DOI: 10.1111/1552-6909.12261
pecially vasomotor menopausal symptoms such as hot flashes. With regard to the association between BMI and vasomotor menopausal symptoms, two contradictory hypotheses exist including (a) the thin hypothesis and (b) the thermoregulatory model. According to the thin hypothesis, women with higher BMIs and greater body fat are less likely to be at risk of vasomotor symptoms such as hot flashes than women with lower BMIs and less body fat (Erlik, Meldrum, & Judd, 1982). This hypothesis asserts that body weight is positively associated with midlife women’s endogenous estrogen levels through the aromatization of androstenedione to estrone in adipose tissue. This thin hypothesis is supported by earlier studies regarding the associations between body weight and menopausal symptoms (Campagnoli, Morra, Belforte, Belforte, & Prelato Tousijn, 1981; Wilber, Dan, Hedricks, & Holm, 1990). However, in recent studies including the Study of Women’s Health Across the Nation (SWAN), researchers have reported that women with higher BMIs suffer from more prevalent and more severe vasomotor symptoms than women with lower BMIs (Fernandez-Alonso et al., 2010; Freeman et al., 2001; Gold et al., 2004; Kumari, Stafford, & Marmot, 2005). These findings have been explained by the thermoregulatory model. The thermoregulatory model asserts that adipose tissue, which inhibits heat dissipation, increases core body temperature so that vasomotor symptoms such as hot flashes occur to release heat and to decrease core body temperature (Anderson, 1999; Freedman, 2005). Although pathological pathways that could explain the association between the BMI and other menopausal symptoms are not defined, previous studies have reported that women with higher BMIs are also more likely to experience more prevalent and more severe somatic menopausal symptoms (Daley et al., 2007), psychological menopausal symptoms (Kumari et al., 2005; Mirzaiinjmabadi, Anderson, & Barnes, 2006), and physical menopausal symptoms (Gold et al., 2000). These positive associations between the BMI and menopausal symptoms have also been reported in studies of diverse ethnic groups of midlife women, including Whites (Gold et al., 2006; Im et al., 2010), African Americans (Freeman et al., 2001; Im et al., 2010), Hispanics (FernandezAlonso et al., 2010), and Arabic women who live in Australia (Lu et al., 2007). However, the significant associations have not been supported in studies for Asian American midlife women (Gold
http://jognn.awhonn.org
IN FOCUS
Chang, S. J., Chee, W., and Im, E.-O.
CNE http://JournalsCNE.awhonn.org
Table 1: Two different BMI classifications by World Health Organization International
Asian populations
Classification
Cutoff points (kg/m2 )
Classification
Cutoff points (kg/m2 )
Underweight
IN FOCUS
Effects of the Body Mass Index on Menopausal Symptoms Among Asian American Midlife Women Using Two Different Classification Systems Sun Ju Chang, Wonshik Chee, and Eun-Ok Im
ABSTRACT Objective: To explore the effects of the body mass index (BMI) on menopausal symptoms among Asian American midlife women using two different classification systems: the international classification and the BMI classification for public health action among Asian populations.
http://JournalsCNE.awhonn.org
Design: Secondary analysis using data from two large Internet survey studies. Setting: Communities and groups of midlife women on the Internet. Keywords Asian American midlife body mass index menopause symptoms
Participants: A total of 223 Asian American midlife women who were recruited over the Internet. Methods: The Midlife Women’s Symptom Index and self-reports of height and weight were used to collect data. The data were analyzed using multiple analyses of covariance. Results: No significant differences in the prevalence and severity scores among three subscales and total menopausal symptoms according to the international classification were found. When the BMI classification for public health action among Asian populations was used as an independent variable, significant differences were found in the severity scores of three subscales and total menopausal symptoms. Results of the post-hoc analyses showed that Asian American midlife women who were in the BMI classification for high risk had significantly more severe menopausal symptoms than those who were in the BMI classification for increased risk. Conclusion: For Asian American women, BMI categorized using the BMI classification for Asian populations is more closely related to the severity of menopausal symptoms than BMI categorized using the international classification. Nurses need to consider the BMI classification for Asian populations when they develop interventions to prevent and alleviate menopausal symptoms among Asian American midlife women.
JOGNN, 43, 84-96; 2014. DOI: 10.1111/1552-6909.12261 Accepted May 2013
Correspondence Sun Ju Chang, PhD, School of Nursing University of Pennsylvania 418 Curie Blvd, Philadelphia, PA 19104. [email protected]
Sun Ju Chang, PhD, is a postdoctoral researcher in the School of Nursing, University of Pennsylvania, Philadelphia, PA.
(Continued)
84
enopause constitutes the permanent cessation of a woman’s menstrual periods due to the discontinuance of hormone production in the ovaries (U.S. Department of Health and Human Services, Office of Women’s Health, 2010). According to the National Institute of Aging (2008), the mean age of menopause is 51, although it varies depending on a woman’s lifestyle (e.g., smoking habits) and medical history (e.g., hysterectomy). However, with changes in the levels of hormones, including estrogen and progesterone, a woman in her forties might undergo menopausal transition or perimenopause (American Society for Reproductive Medicine, 2012; National Institute of Aging, 2008). The period after menopause
M
is known as postmenopause (American Society for Reproductive Medicine, 2012; National Institute of Aging, 2008). Throughout the menopause process, midlife women between age 40 and 60 might experience various menopausal symptoms, including physical symptoms (e.g., hot flashes, night sweats, vaginal dryness, stiffness and soreness in the joints and muscles), psychological symptoms (e.g., forgetfulness, difficulty falling or staying asleep, depressed mood), and psychosomatic symptoms (e.g., dizziness, fatigue, headache) (Im, 2006). Because these symptoms can affect a woman’s quality of life, health, and well-being (Daley et al., 2007; Waidyasekera, Wijewardena, Lindmark, & Naessen, 2009), health
C 2013 AWHONN, the Association of Women’s Health, Obstetric and Neonatal Nurses
http://jognn.awhonn.org
IN FOCUS
Chang, S. J., Chee, W., and Im, E.-O.
CNE http://JournalsCNE.awhonn.org
care providers and researchers have devoted considerable attention to identifying risk factors for the development and aggravation of menopausal symptoms. With regard to risk factors for the development and aggravation of menopausal symptoms, previous researchers have reported several factors, including menopausal stage, age, education, body mass index (BMI), smoking, diet, physical activity, and alcohol use (Gold et al., 2006; Perez, Garcia, Palacios, & Perez, 2009). Among these factors, the BMI, which is related not only to menopause age and menopausal symptoms but also to metabolic syndrome and cardiovascular disease after menopause, is considered an important factor in many menopausal symptomsrelated studies because the BMI has the potential to be modified through interventions (Carr, 2003; Fernandez-Alonso et al., 2010; Morris et al., 2012). In the current literature, researchers have reported a positive association between BMI and menopausal symptoms among multiethnic groups of midlife women, including White, African American, and Hispanic (Fernandez-Alonso et al., 2010; Im, Lee, Chee, Brown, & Dormire, 2010; Lu, Liu, & Eden, 2007). However, the association between BMI and menopausal symptoms among Asian American midlife women who experience menopausal symptoms has not been demonstrated in the current literature (Gold et al., 2006; Im et al., 2010). A plausible reason might be the differences in body composition between Asian populations and Western populations. Many Asian populations, even Asian Americans, have a higher percentage of body fat than Western populations who are at the same BMI (Lauderdale & Rathouz, 2000; World Health Organization [WHO], 2004). For this reason, an alternative BMI classification for public health action among Asian populations that reflects Asian-specific body composition has been introduced in health sciences (WHO, 2004). However, virtually none of the studies on Asian American midlife women has been conducted using the alternative BMI classification for public health action among Asian populations. Also virtually no researchers have explored whether the alternative BMI classification for public health action among Asian populations would be more appropriate for Asian American midlife women than the current BMI classification. To design and develop adequate interventions for preventing and alleviating Asian American midlife women’s menopausal symptoms, the effects of the
JOGNN 2014; Vol. 43, Issue 1
The Body Mass Index Classification introduced by the World Health Organization for public health action among Asian populations reflects Asian-specific body composition.
BMI on menopausal symptoms need to be investigated while considering Asian-specific body composition. Hence, the purpose of the secondary analysis was to explore the effects of the BMI on menopausal symptoms among Asian American midlife women by using two different classification systems. For this purpose, we began with a review of two BMI classification systems, the international classification (current classification) and the BMI classification for public health action among Asian populations. Then we reviewed the associations between BMI and menopausal symptoms in light of the existing hypotheses, including the thin hypothesis and the thermoregulatory model. Finally, the effects of the BMI on the prevalence and severity of menopausal symptoms among Asian American midlife women were examined under the two different classification systems using the findings from a secondary analysis.
Background Body Mass Index and Classification Systems Body mass index is calculated as a person’s weight (in kilograms) divided by his or her height squared (in meters) (kg/m2 ). By comparing a person’s weight to height, BMI can be used to indirectly measure a person’s body fat (Vasudevan, Stotts, Anabor, & Mandayam, 2012; WHO, 2004). Body mass index is not a diagnostic measurement. However, because BMI can easily be used to assess overweight and obesity among the general population and has been reported to be a reliable indicator of obesity-related diseases such as type 2 diabetes and coronary heart disease, it is widely used in the health care field worldwide (Centers for Disease Control and Prevention [CDC], 2011; Chiu, Austin, Manuel, Shah, & Tu, 2011; Vasudevan et al.; WHO, 2004). For interpretation of BMI, BMI cutoff points with international classification of weight status for adults were introduced by the WHO) (1995, 2000) (see Table 1). These BMI cutoff points and the international classification have been widely accepted for international use as screening measurements to identify individuals at high risk for obesity-related diseases (CDC, 2011; WHO, 2004). However, because these BMI cutoff points were based on
Wonshik Chee, PhD, is an associate professor in the School of Nursing, University of Pennsylvania, Philadelphia, PA Eun-Ok Im, PhD, MPH, RN, CNS, FAAN, is the Marjorie O. Rendell Endowed Professor in the School of Nursing, University of Pennsylvania, Philadelphia, PA
85
IN FOCUS
Effects of the Body Mass Index on Menopausal Symptoms
CNE http://JournalsCNE.awhonn.org
Western populations, they might not be sensitive to detection of potential risk in other populations (Rush, Freitas, & Plank, 2009). For example, Asian populations have a higher body fat percentage at a lower BMI value and a higher risk of diabetes, heart disease, and even death than Western populations at the same BMI (Lewis et al., 2009; WHO, 2004). These tendencies have been observed in Asian immigrant populations as well. For example, in a study in New Zealand, Asian Indians at BMI values ranging from 24 to 26 kg/m2 had the same body fat percentage as Europeans at a BMI value of 30 kg/m2 (Rush et al., 2009). Also, in a study among Asian Americans, the prevalence of metabolic syndrome of Asian Americans at BMI values ranging from 19.6 to 19.9 kg/m2 was comparable to that of non-Hispanic Whites at a BMI value of 25 kg/m2 (Palaniappan, Wong, Shin, Fortmann, & Lauderdale, 2011). Researchers assessing diabetes risk using ethnic-specific cutoff points also found that BMI values of Chinese and South Asians who lived in Canada and developed diabetes were lower than those of Whites (Chiu et al., 2011). For these reasons, researchers and health care providers have suggested the need for Asian-specific BMI cutoff points that can be used to effectively screen overweight and obese individuals among Asian populations. In 2004, the WHO reported that the BMI values indicating high risk for type 2 diabetes and cardiovascular disease in Asian populations were lower than the current WHO cutoff points for being overweight. However, the WHO suggested an alternative BMI classification for public health action among Asian populations (see Table 1). This alternative BMI classification was proposed instead of redefining BMI cutoff points for Asian populations due to the necessity for a standardized approach around the world and a lack of available data for clear BMI cutoff points for Asian populations. Although new BMI cutoff points for Asian populations have been suggested in some studies (Gu et al., 2006; Pan et al., 2004; Stevens & Nowicki, 2003; Wen et al., 2009), no consensus has been reached in terms of clear points for this population. Hence, this study used the BMI classification for public health action among Asian populations as suggested by the WHO.
Body Mass Index and Menopausal Symptoms Current literature has reported the associations between BMI and menopausal symptoms, es-
86
JOGNN, 43, 84-96; 2014. DOI: 10.1111/1552-6909.12261
pecially vasomotor menopausal symptoms such as hot flashes. With regard to the association between BMI and vasomotor menopausal symptoms, two contradictory hypotheses exist including (a) the thin hypothesis and (b) the thermoregulatory model. According to the thin hypothesis, women with higher BMIs and greater body fat are less likely to be at risk of vasomotor symptoms such as hot flashes than women with lower BMIs and less body fat (Erlik, Meldrum, & Judd, 1982). This hypothesis asserts that body weight is positively associated with midlife women’s endogenous estrogen levels through the aromatization of androstenedione to estrone in adipose tissue. This thin hypothesis is supported by earlier studies regarding the associations between body weight and menopausal symptoms (Campagnoli, Morra, Belforte, Belforte, & Prelato Tousijn, 1981; Wilber, Dan, Hedricks, & Holm, 1990). However, in recent studies including the Study of Women’s Health Across the Nation (SWAN), researchers have reported that women with higher BMIs suffer from more prevalent and more severe vasomotor symptoms than women with lower BMIs (Fernandez-Alonso et al., 2010; Freeman et al., 2001; Gold et al., 2004; Kumari, Stafford, & Marmot, 2005). These findings have been explained by the thermoregulatory model. The thermoregulatory model asserts that adipose tissue, which inhibits heat dissipation, increases core body temperature so that vasomotor symptoms such as hot flashes occur to release heat and to decrease core body temperature (Anderson, 1999; Freedman, 2005). Although pathological pathways that could explain the association between the BMI and other menopausal symptoms are not defined, previous studies have reported that women with higher BMIs are also more likely to experience more prevalent and more severe somatic menopausal symptoms (Daley et al., 2007), psychological menopausal symptoms (Kumari et al., 2005; Mirzaiinjmabadi, Anderson, & Barnes, 2006), and physical menopausal symptoms (Gold et al., 2000). These positive associations between the BMI and menopausal symptoms have also been reported in studies of diverse ethnic groups of midlife women, including Whites (Gold et al., 2006; Im et al., 2010), African Americans (Freeman et al., 2001; Im et al., 2010), Hispanics (FernandezAlonso et al., 2010), and Arabic women who live in Australia (Lu et al., 2007). However, the significant associations have not been supported in studies for Asian American midlife women (Gold
http://jognn.awhonn.org
IN FOCUS
Chang, S. J., Chee, W., and Im, E.-O.
CNE http://JournalsCNE.awhonn.org
Table 1: Two different BMI classifications by World Health Organization International
Asian populations
Classification
Cutoff points (kg/m2 )
Classification
Cutoff points (kg/m2 )
Underweight
