Obesity
Adults with asthma are at increased risk of obesity [38]. Obesity is a possible risk factor for development of asthma in women [2] and for resting dyspnea in women with asthma [39]. It is associated with poor asthma-related QOL and use of emergency/urgent services [40]. Evidence is mixed regarding the link between BMI and asthma control [41–43], but the following studies suggest that women who are overweight/obese face unique asthma management challenges. Valerio and colleagues found that in a sample of 808 women enrolled in a randomized trial of an asthma-education intervention, nearly 7 out of 10 were overweight (BMI ≥ 25) or obese (BMI ≥ 30), and nearly a quarter were “extremely obese” (BMI > 35) [44]. This subgroup of women was more likely to have persistent asthma, comorbid GERD and urinary incontinence, to be non-white, and to have lower levels of education and income. Being overweight was also associated with greater use of health care services and having greater psychosocial challenges (ie, a higher need for asthma-related social support and lower asthma-related quality of life). These authors suggest the need to design communications for overweight women with asthma that recognize “the specific cultural and social influences on their asthma management behaviors” [44] with a focus on psychosocial needs, while incorporating existing social support networks. In the previously discussed study by Janevic and colleagues [29] the average BMI of the interview participants was 36.0, and a number of respondents identified weight loss as the self-care behavior that they thought would benefit them the most across multimorbid conditions. Therefore, health care providers should provide appropriate counseling and/or referrals to help women with asthma achieve weight loss goals. Given trends over time showing increasing prevalence of asthma and obesity [45,46], interest is growing in the asthma research community about the interaction of the 2 conditions.
Hormonal Factors
Hormones exert a significant effect on asthma in women, and must be considered in clinical and self-management of the disease. Hormone levels fluctuate during the menstrual cycle, with a surge of estradiol (a type of estrogen) at the time of ovulation around day 14, accompanied by low levels of progesterone. During the luteal phase (day 14–28 of the menstrual cycle), estrogens decrease while progesterone levels increase then decrease again before onset of menstruation [47]. During pregnancy, levels of estrogens and progesterone increase and are the highest during the third trimester, when women usually experience good asthma control. Then, during menopause both estradiol and progesterone levels drop to lower levels than those during any phase of menstruation. In addition to the role in the menstrual cycle, there are estrogen receptors (ER-α and ER-β) which are expressed in the human lung and have a role in both airway responsiveness (relaxation) and inflammation [48]. Estrogen also acts directly on cells of the immune system to stimulate airway inflammation, particularly when allergens are present [48]. Further discussion about these contrasting actions of estrogen can be found in a recent review [48].
During the reproductive years, 30% to 40% of women with asthma report perimenstrual symptoms. Forced expiratory volume in 1 second and forced vital capacity are lowest in the periovulatory period, when estrogen levels are high. In contrast, during the luteal phase, studies have shown increased airway hyperreactivity, especially in the premenstrual period when estrogen levels are low [49]. However, when asthma patients with and without perimenstrual symptoms are evaluated, there is no significant difference in their perimenstrual estrogen and progesterone levels [50]. Clark et al [15] found women participating in a self-management intervention, which included checking daily peak flow rates, reported significantly more menstrual and perimenstrual asthma symptomatology than the control group. This suggests that some women with asthma have may have, but do not recognize, perimenstrual symptoms. Further elucidation of the incidence of symptomatology related to the menstrual cycle as well as the role of hormonal variation is an area for future research efforts.
At the time of menopause and continuing to postmenopause, levels of both estrogen and progesterone drop to below those during the reproductive years, leading to uncomfortable symptoms in many women. Hormone replacement therapy (HRT) with either estrogen alone or estrogen-progesterone combination effectively improves these, but there is concern for potential effects on asthma prevalence and severity. Two recent large studies support this concern. Postmenopausal women followed for 10 years in the Nurses’ Health Study with a history of HRT had an increased risk of new onset asthma when compared to postmenopausal women with no history of estrogen use (RR = 2.30, 95% CI 1.69–3.14) [51]. This persisted in estrogen-progesterone users. A large French cohort confirmed the increased onset of new asthma in users of estrogen-alone replacement therapy (HR = 1.54, 95% CI 1.13–2.09). However, this effect decreased with time if estrogen had been discontinued, and they did not find a similar increase in users of estrogen-progesterone combination therapy [52]. In contrast, Bonelykke et al [53] found an association between ever using HRT and first-ever hospital admission for asthma, in postmenopausal women (HR 1.46, CI 1.21–1.76), and this risk increased with duration of HRT use. It is clear that physicians need to be aware of these potential respiratory complications, inform their patients, and consider new-onset asthma when women on HRT bring complaints of dyspnea, cough, or wheeze. Future randomized trials are needed to clarify the relationship between HRT and asthma, and to test ways to optimize asthma self-management in women experiencing these transitions.
Older Women and Asthma
Although the bulk of research on asthma focuses on children and young adults, asthma in the elderly is receiving increased attention [54], in part because this demographic group has the highest asthma mortality rate and the most frequent hospitalizations [6,55]. In a sample of midlife and older women from the Nurses’ Health Study who had been diagnosed with persistent asthma, Barr et al found that adherence to asthma medication guidelines decreased with age [54]. In this study, women with more severe asthma and those with multimorbidity were less adherent than those without comorbidities, as were women who spent more hours caregiving for an ill spouse. The authors concluded that asthma is undertreated among older women.
Baptist et al (2014) describe several challenges to asthma management of older women by clinicians and by the women themselves [55]. For example, elderly women may be at increased risk for adverse effects of inhaled corticosteroids. Certain medications used to treat comorbidities, such as beta-blockers and aspirin, may also exacerbate asthma symptoms. In terms of self-management, older women may have a decreased ability to perceive breathlessness, requiring monitoring with a peak flow meter to detect reductions in airflow. Comorbidities are particularly prevalent in this age group, and asthma symptoms may be confused with symptoms of other conditions, such as heart disease [56]. Baptist and colleagues note factors common among elderly women that pose potential barriers to successful self-management of asthma, including limited income, poverty, depression, and caregiving [55]. They also mention that functional limitations such as those due to arthritis, visual difficulties, or weakened inspiratory strength can make inhaler use more difficult. It should also be noted that some behaviors may promote asthma self-management in this group; for example, Valerio and colleagues [57] found that women over age 50 were more likely than younger women to keep a daily asthma diary when asked to do so as part of a self-management intervention [57].
Evidence-Based Asthma Self-Management Interventions for Women
For women to achieve optimal asthma control, the unique factors as described above that influence their symptoms and management need to be addressed [58]. Several examples can be found in the literature of behavioral interventions that focus on the particular self-management challenges faced by women. Clark and colleagues reported the results of an RCT of the Women Breathe Free (WBF) program [15,16]. This intervention consisted of asthma self-management education delivered over 5 telephone sessions by a health educator. WBF content was based on self-regulation theory, which involves observing one’s behavior and making judgments on the observations, testing strategies to improve asthma management, and reacting to positive results of these strategies with enhanced self-efficacy and outcome expectations, ie, the belief that a given strategy will produce the desired results [59]. In WBF, participants used a problem-solving process based on this framework to carry out recommendations in their physician’s therapeutic plan. WBF also incorporated special attention to sex- and gender-based factors in asthma management.
Over a 12-month period, women who participated in the intervention relative to controls experienced significant reductions in nighttime symptoms, days of missed work/school, emergency department visits, and both scheduled and urgent office visits. Intervention group women also reported decreased asthma symptoms during sexual activity, improved asthma-related quality of life, and increased confidence to manage asthma. At long-term follow-up (2 years from baseline), persistent positive effects of the intervention were found on outpatient visits for asthma symptom level during sexual activity, days of missed work/school, asthma-related quality of life, and confidence to manage asthma [60].
In a follow-up study, Clark and colleagues [61] developed the “Women of Color and Asthma Control” (WCAC) program. WCAC incorporates the theoretical orientation and many of the program elements of Women Breathe Free, but has been adapted to be responsive to the needs and preferences of African-American women. Poverty and race are associated with greater asthma morbidity and mortality [5,62,63]. African-American women and women of low socioeconomic status are particularly vulnerable to asthma and associated morbidity and mortality, making this an important group for intervention. Culturally responsive components in the WCAC intervention include use of culturally relevant activities and beliefs when discussing triggers and barriers to asthma management, as well as culturally appropriate visuals. This ongoing trial will test WCAC’s effect on ED visits, hospitalizations, and urgent care; asthma symptoms; and asthma-related quality of life at 1 year and 18 months from baseline.
In a small RCT among women with asthma, Bidwell and colleagues tested a program consisting of 10 weeks of yoga instruction (including breathing practices, poses, and meditation/relaxation skills) in a group setting followed by 10 weeks of home practice [64]. Women in the intervention group reported improved quality of life, as measured by the St. George’s Respiratory Quality of Life questionnaire [65], and participants also had decreased parasympathetic modulation in response to an isometric forearm exercise. They conclude that yoga is a promising modality for improving quality of life among asthma patients and that these changes may be linked to better autonomic modulation. Although this program was not designed specifically for women, yoga is practiced significantly more frequently among women compared to men [66,67], and thus has the potential to be widely used in this group.