|Home | About | Journals | Submit | Contact Us | Français|
To describe clinical and psychosocial characteristics of overweight women with asthma.
Telephone interview and medical record review involving 808 women with asthma participating in a randomized study to identify those who were overweight. We assessed the relationship of their weight to asthma symptoms, health care use, quality of life, self esteem, need for social support and demographic characteristics. Regression analysis were used to investigate relationships between overweight and asthma.
Sixty eight percent of the women in the study were overweight or obese. Demographic characteristics associated with overweight in women with asthma included being minority (p=0.000), having lower education (p=0.000) and lower household income (p=0.024). Overweight was associated with greater health care use, comorbidities (acid reflux, and urinary incontinence) and persistent disease (p=0.001). Overweight women exhibited less self esteem (p=0.002) and lower perceived quality of life (p=0.000).
Overweight females with asthma experience significant challenges due to their weight, more persistent and severe disease, specific comorbidities and lower levels of obtaining psychosocial resources. Clinical consultations and interventions should account for the influence of overweight on asthma control and health status in female patients.
Weight and asthma is a topic increasingly discussed due to the rise of obesity in the United States (Jarvis, Chinn, Potts et al. 2002). Although the natural history of asthma as it relates to weight is not fully understood (Chinn, 2003) the two conditions pose significant public health problems. Prevalence data show that almost twice as many women have asthma compared to their male counterparts (Barnes, Heyman, & Schiller, 2007). Several investigators have shown that women experience more asthma symptoms (McCallister, 2008: Linry, 2008), have higher rates of clinical visits, hospital admissions and readmissions for asthma, and have higher rates of asthma-related mortality (CDC, 2007; CDC, 2004). Women with asthma who are overweight or obese are thought to experience greater problems with the disease than women of average weight (Burgess, Walters et al., 2007; Clark et al., 2007).
The interplay of biological sex and weight in the epidemiology and etiology of asthma has been recognized. It is during adolescence and the onset of menses when the prevalence of the condition shifts from predominately impacting the health of young males to a disease of females (Almqvist, Worm, & Leynaert, 2007). Venn and colleagues (1998) posit that the tendency for adolescent females to experience weight gain during this time may account for the increases observed in asthma prevalence. Researchers have also found a correlation between higher body mass index (BMI) in childhood and the onset of adult asthma in females (but not males) (Beckett et al., 2001; Castro et al., 2001, Chen, Dales, Krewski and Breithaupt 1999). One hypotheses for the relationship between weight, sex and asthma is the effect of increased estrogen levels associated with obesity on the smooth muscles of the airway and on inflammatory and immune system function (McCallister, 2008; Weiss & Shore, 2004).
Additional studies have shown that higher BMI is more evident in those with asthma compared to those who have never had the condition (Vortmann & Eisner, 2008; Kim & Camargo, 2003). Obese individuals with asthma may have more airway obstruction than their normal weight counterparts (Thomson et al., 2003). Those with asthma who lose weight appear to experience reductions in symptoms and improved airflow (Castro-Rodriguez et al., 2001). The relationship between obesity and asthma may also have both a hormonal and a metabolic component (Gomez Real et al., 2007). Recent research has identified the implications of the levels of serum leptin, a hormone produced by adipocytes which is elevated in obese individuals, on asthma (Perfetto et al., 2004; Weiss & Shore, 2004). These findings have prompted researchers to consider the need of different asthma medications for adult based on their weight (Peters-Golden et. al, 2006).
Existing research suggests that although we do not know the exact mechanisms between overweight and the onset or exacerbation of asthma, women who are overweight or obese are likely to have different management challenges than women of average or lower weight. Given the disparities in asthma between men and women, it is important to not only recognize the sex difference, but also to identify and understand the specific asthma management needs of this particular population. Very little is known about the day-to-day asthma management challenges and psychosocial factors facing overweight women. The purpose of this study was 1) to describe a population of overweight women with asthma, 2) to better understand the asthma-related difficulties they face, and how these may impact daily asthma management, and 3) to identify how educational interventions might be designed and tailored to better manage their asthma.
The study was conducted from baseline data, as part of a randomized clinical trial to assess the effects of an intervention for women with asthma (Clark, et al. 2007). All study procedures were approved by the University of Michigan Institutional Review Board. Patients of the University of Michigan Health System (UMHS) participated in the study if they met the following criteria: 1) 18 years of age and older; 2) diagnosis of asthma by a UMHS physician; 3) presence of active symptoms in the past 12 months; 4) enrolled in a participating UMHS clinic; 5) no extenuating medical or mental condition to preclude participation; and 6) access to a telephone. Patients from the asthma-related clinics were identified by the physicians and sent a study invitation letter and postcard (N = 2336). A total of 1,081 of the women contacted were eligible to participate in the study (met all study criteria and had working phone number) and were sent additional study information and consent forms. Ultimately, 808 (75%) of the women consented and completed the baseline telephone interview. Non consent of the eligible participants was attributable primarily to a lack of interest in the study or the perception of not having asthma.
Trained and supervised interviewers collected baseline data by telephone. Demographic data (e.g. household income, education level and race/ethnicity) along with weight and height were collected. Data regarding comorbidities and smoking history were also collected. Body Mass Index (BMI) was calculated based on the self-reported weight and height by the participants using the Centers for Disease Control and Prevention recommended calculation for adults. (CDC, 2007; Kushner & Blatner, 2005). In this study, we used the CDC BMI calculation and the standard weight status categories associated with BMI ranges for adults to classify participants as either normal or overweight and obese.
The National Asthma Education Prevention Program (NAEPP) guidelines were used to classify women's symptoms (NAEPP, 2007; Clark, 2007). The frequency of asthma daytime and nighttime symptoms experienced in the past 12 months was collected and used to determine asthma severity classification. A dichotomous variable for categorization of persistent disease was used in the analysis.
Asthma-related health care utilization was captured for the number of hospitalizations, emergency department (ED) visits, scheduled asthma visits, unscheduled urgent visits, and follow-up visits for an asthma episode to a clinic or doctor's office in the past twelve months. Patient reports of health care utilization were verified through hospital records for the corresponding time periods. Sex and gender related queries focused on symptoms related to hormonal, pregnancy and menstrual cycle, household-related tasks, and social and sexual activity.
Quality of life was measured using the the mini Asthma Quality of Life Questionnaire (Juniper, 1993). The 10-item scale captured: 1) activity limitations, 2) asthma symptoms, 3) emotional function, and 4) environmental stimuli. Items related to the level of a woman's self-esteem (Rosenberg, 1986) and the availability and need for asthma-related social support (e.g., transportation to asthma health care appointments and assistance with care needs) were also measured.
Statistical analyses included simple frequencies and descriptive statistics of variables of interest. Weight status was our outcome of interest. A dichotomous variable was used to categorize the study sample using CDC BMI standard weight status categories for adults as either overweight and obese (BMI = 25 or greater) or normal and underweight (BMI <24.9). Logistic regression was conducted to examine the relationship between weight status and demographic and clinical characteristics and comorbidities. Independent sample t-tests were completed to assess differences in health care utilization (i.e., hospitalizations and ED use) and symptoms between participants who were categorized as overweight and obese compared to those who were not. A confidence level of 95% was accepted as significant.
Table 1 shows demographic data and clinical characteristics of the 808 participating women. The mean age of the study participants was 48 (SD=13.7); the majority of women had an educational level of 2 years of college or greater (70%); 66% were employed and 29% had a household income of $40,000 or less per year. Sixty-three percent of the women were married and 83% were Caucasian. Thirteen percent of the study women had severe persistent asthma and 58% reported one or more chronic health conditions. Forty-five percent of the study women were overweight or obese and 23% were extremely obese.
Women who were overweight or obese were statistically significantly more likely to have hospital admissions and emergency department visits for asthma than those of lower weight (see Table 2). Additionally, women who were overweight or obese had statistically significant higher rates of unscheduled urgent care visits, regularly scheduled asthma visits, and follow-up visits for an asthma episode compared to their counterparts who were not overweight.
As presented in Table 3, the measures of psychosocial functioning indicate that those who were overweight or obese had statistically significant lower levels of self-esteem and lower quality of life compared to those who are not overweight or obese. Women who were overweight or obese also needed significantly higher levels of social support.
Table 4 shows the association of weight and sample characteristics. Study participants who were overweight or obese were more likely to be minority (OR=3.08; 95% CI (1.744, 5.463); have lower levels of education (OR=2.136; 95% CI (1.494, 3.055); and have lower household income, <$40,000 per year (OR=1.823; 95% CI (1.083. 3.066). Furthermore, women who were overweight or obese were much more likely to report problems with acid reflux (OR=1.983; 95% CI (1.443, 2.725), a condition associated with asthma, and urinary incontinence (OR=1.978; 95% CI (1.452, 2.695) and more severe persistent disease (OR=1.66; 95% CI (1.223, 2.259).
Asthma may be more challenging and severe for overweight and obese women than for women who are not overweight. These findings are similar to those of other studies where greater asthma-related risk and higher emergency department use in populations were evident in overweight or obese patients (Vortmann & Eisner, 2008; Oh, 2008; Akerman et al., 2004; Thomson et al., 2003; Chen et al., 2002; Beckett et al., 2001). Findings also suggest a number of factors should be considered in clinical counseling or educational interventions when aiming to assist women who are overweight or obese manage their asthma more effectively.
Carefully designed communications for overweight patients that recognize the specific cultural and social influences on their asthma management behaviors may be needed; as are materials and counseling approaches geared to a lower education and income level. Given the asthma disparities in females and the prevalence rates of asthma in underserved minority populations (Apter, 2009; McCallister, 2008: Linry, 2008; CDC, 2007), it is necessary that the patient's health literacy be taken into consideration as clinical and educational interventions are designed. The association of greater weight with higher health care utilization rates identified also supports the need for health care that addresses the specific asthma-related risk of those who are overweight or obese. Helping women to recognize that their need for more health care is influenced by their weight may also raise awareness of the connection between weight and adverse asthma outcomes.
Given the possible psychosocial needs of overweight women identified, a greater sensitivity may be required when providing care, advice, or in the design of an asthma management program for the patient who is overweight or obese. It is important to find ways to tailor asthma regimens and clinical advice for women based on their own perceptions of psychosocial needs (i.e. quality of life, self-esteem and social support). Therefore, finding novel strategies to build self esteem seem warranted; including that respect is evident on the part of the health care provider and that he or she explicitly communicates praise and encouragement for effective management steps undertaken by the patient (Clark, 2008). A helpful strategy that may address both lower levels of self esteem and needs for social support in the population may be to include significant others in the clinical encounter or intervention program. Studies have shown that patients frequently follow the advice of their friends rather than their clinicians (Gallant, 2003). Given the importance of social support to overweight women, finding ways to make allies of these significant others likely deserves attention. Other useful strategies may include recommending therapies and means of administration that are least disruptive to a woman's daily routine; identifying when to use medicines preventively before socializing; emphasizing the need for continuous use of medicines to reduce interrupted sleep, if sleep disruptions are frequent (Clark, 2007). Tailored therapy and advice may increase a women's asthma control self-efficacy (belief in her ability to perform the needed task) and lead to better asthma management and outcomes (e.g., quality of life, health care utilization) (Martin, Catranbone, Kee, et al., 2009).
The overweight woman is likely to have more severe (persistent) asthma and need to manage multiple conditions and limitations. Programs and counseling that enhance management when there are more frequent symptoms and more complicated medical regimens may be needed to help women achieve asthma control. Helping women to distinguish the symptoms and the remedies for asthma in contrast to their accompanying conditions may help them to more effectively follow recommended regimens.
There are several limitations that should be noted. The women studied were not selected to be representative of the general population of women with asthma and as a result, these findings may not be generalizable. However, the study participants are likely not dissimilar to populations seeking service in health care institutions who are willing to take part in asthma research. A strength in this study is the validation of health care utilization reports through the review of medical records; increasing the validity of all reported data. Further, women of color comprised 17% of the sample. As race/ethnicity was a significant predictor of overweight and associated problems, studies specific to subgroups of minority women should be further explored. Finally, BMI was computed from self reported height and weight. Persons who are obese tend to underreport their weight (Lawlor, et al., 2002). Underreporting of weight may show weaker associations between asthma and obesity in this study than may actually be evident.
Overweight is a significant problem among women with asthma and they are likely to face not only a greater number, but more serious obstacles related to management of their disease. This study points to the need for additional investigation into the clinical and psychosocial challenges facing overweight women attempting to manage asthma. Evaluation of interventions tailored to help overweight women with asthma may also be needed. Consideration of the special challenges evident in these findings should be part of clinical counseling and asthma education programs aimed at helping women who are overweight improve health status and outcomes.
Statement of Interest: The authors have no conflicts of interest or disclosures related to this study or to the subject of the article. The research was supported by grant 1 R18 HL60884–01 from the Division of Lung Diseases of the National Heart, Lung, and Blood Institute.
Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Melissa A. Valerio, Assistant Professor, Health Behavior & Health Education, University of Michigan School of Public Health, 109 Observatory, Ann Arbor, MI 48109-2029, (734) 763-0673; Fax: (734) 763-7379, E-mail: ude.hcimu@oirelavm.
Z. Molly Gong, Head, Data Analysis, Center for Managing Chronic Disease, University of Michigan, 109 Observatory, Ann Arbor, MI 48109-2029, (734) 763-6412; Fax: (734) 763-7379, E-mail: ude.hcimu@gnogm.
Si Jian Wang, Biostatistician, Center for Managing Chronic Disease, University of Michigan School of Public Health, 109 Observatory, Ann Arbor, MI 48109-2029, (734) 763-1457; Fax: (734) 763-7379, E-mail: ude.hcimu@gnawjis..
William F. Bria, Chief Medical Information Officer, Shriners Hospitals for Children, 12502 Pine Dr, Tampa, FL 33612, (813) 972-2250; Fax: (813) 975-7125, Email: gro.tenenirhs@airbw.
Timothy R. Johnson, Bates Professor of Women and Children, Professor & Chair, Department of Obstetrics & Gynecology, University of Michigan Health System, L4000 Women's Hospital, 1500 East Medical Center Drive, Ann Arbor, MI 48109-0276, 734-764-8123; Fax: 734-763-5992, Email: ude.hcimu@jbrt.
Noreen M. Clark, Myron E. Wegman Distinguished University Professor, Director, Center for Managing Chronic Disease, University of Michigan, 109 Observatory, Ann Arbor, MI 48109-2029, (734) 763-1457; Fax: (734) 763-7379, E-mail: ude.hcimu@kralcmn..