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* From the Center for Managing Chronic Disease (Drs. Clark and Gong), and the Department of Biostatistics (Mr. Wang), School of Public Health, and the Department of Obstetrics and Gynecology (Dr. Johnson), School of Medicine, University of Michigan, Ann Arbor, MI; the Department of Biostatistics (Dr. Lin), School of Public Health, Harvard University, Cambridge, MA; and Shriners Hospitals for Children (Dr. Bria), Tampa, FL.
Correspondence to: Noreen Clark, PhD, University of Michigan, School of Public Health, 109 S Observatory, Ann Arbor, MI 48109; e-mail: nmclark{at}umich.edu
Abstract
Background: Women with asthma have greater mortality and morbidity than men in the United States. To date, there has been no rigorous evaluation of an intervention focused on the particular problems in asthma management faced by women. This study was a randomized clinical trial of a self-regulation, telephone counseling intervention emphasizing women’s concerns, and sex and gender role factors in their management of asthma.
Methods: A total of 808 women with diagnosed asthma were randomly assigned to the intervention group or a usual-care control group, including conventional asthma education. Interviews and medical record data were collected to assess psychosocial factors, and the behavioral factors of functioning, quality of life, symptoms, and health-care use at baseline and the subsequent 1 year. Generalized estimating equations, identity link, logit link, and log link were employed to analyze the data.
Results: Compared to control subjects, the women receiving treatment had greater annual reductions in the average number of nights with asthma symptoms (p = 0.04), days of missed work/school (p = 0.03), emergency department visits (p = 0.04), unscheduled office visits (p = 0.01), and scheduled office visits (p = 0.04). They had greater recognition of asthma symptoms during the menstrual cycle (p = 0.0003), had decreased asthma symptoms with sexual activity (p = 0.008), and had greater improvement in quality of life (p = 0.0005), self-regulation (p = 0.03), and self-confidence to manage asthma (p = 0.001).
Conclusion: The intervention improved women’s clinical status, functioning, quality of life, and health-care use. A program with a focus on asthma management problems particular to women can significantly assist female asthma patients.
Key Words: asthma • chronic conditions • management by patients • outcomes • women’s health
Over 9% of women in the United States have asthma compared to 5% of men. Asthma has a differential impact on women. During the last decade, the increase in the asthma mortality rate for men was 34%, whereas for women it was 59%. Women consistently have higher rates of clinic visits, hospital admissions, and hospital readmissions for asthma than men.123 Reports in the literature are beginning to describe differences in etiology, natural history, and asthma management needs that may be attributable to the sex or gender role of the patient.
Studies4567 have suggested that asthma symptoms may worsen for as many as 30 to 40% of women during menses. Cough and breathlessness are more severe in women with menstruation-linked asthma, and these patients may exhibit a decrease in their peak expiratory flow rate.68 Women with menstruation-linked asthma have more visits to the emergency department (ED) and more hospitalizations, and they require extra medication during the premenstrual and/or menstrual weeks.47 Women with asthma who are receiving estrogen replacement therapy (ERT) have an increased risk of asthma symptoms910 and a decreased peak flow requiring more therapy with inhaled bronchodilators.1112 One third of pregnant women with asthma experience a worsening of asthma symptoms during pregnancy.13
Within most cultures, women have the primary responsibility for child care and household management. Hence, they are exposed to many potential asthma triggers.1415 Allergens including dust mites, fungi, molds, and yeasts may be problematic for some women.141516 Sensitizing agents such as household sprays, cleaning materials, perfumes, scented personal care products, cosmetics, and other products have been reported as triggers.17
To date, no rigorously evaluated intervention has focused on the particular problems that women face in the management of asthma. This randomized clinical trial evaluated a self-regulation intervention that emphasized women’s concerns and sex and gender role factors in the management of asthma. The hypotheses were that women in the intervention group when compared to women in the control group would exhibit greater reductions in the following: (1) the number of days and nights with symptoms; (2) the number of days of missed work or school; (3) the number of office visits, ED visits, and hospitalizations for asthma; and (4) the number of management problems related to sex and gender roles. Further, improvements in quality of life, self-regulation, and self-confidence to perform asthma management tasks were expected in these women.
Materials and Methods
Study Design and Sample
A random controlled study design was employed using two groups of female patients at the University of Michigan Health System (UMHS) who met the study criteria. Because a range of factors was expected to influence outcomes beyond asthma severity, the decision was made not to match women in the two groups with respect to disease severity. Patients were randomly assigned to an intervention group or a usual-care group. Usual care within the UMHS comprises treatment based on National Asthma Education Prevention Program (NAEPP) guidelines for the diagnosis and management of asthma,18 as well as telephone follow-up for purposes of patient monitoring. Asthma education is provided at the time of clinic visit. This education is similar to that found in most health-care institutions and does not emphasize sex and gender issues in asthma management.
Study procedures were approved by the institutional review board of the University of Michigan Medical School. No adverse events were reported during the course of the study. The criteria for recruitment of all study participants were as follows: (1) 
18 years of age; (2) diagnosis of asthma by a UMHS physician, based on NAEPP guidelines for the diagnosis and management of asthma18; (3) the presence of active symptoms in the past 12 months (including any from among persistent cough, chest tightness, chest heaviness, shortness of breath, wheezing, and difficulty sleeping because of breathing problems); (4) having been enrolled as a patient in one of the participating asthma-related clinics; (5) no extenuating medical or mental conditions (ie, terminal illness or dementia); and (6) access to a telephone. The UM Data Warehouse of the University of Michigan Administrative Information Services provided a list of women who met the study criteria. Figure 1
presents the participation trajectory of 2,336 women who were sent study invitation letters and response postcards during the 3.5-year recruitment period. All women who did not return the postcard were contacted by telephone. Consent forms were mailed to a total of 997 women who agreed to participate when telephone contact was made. Ultimately, 808 respondents who returned the completed consent forms by mail provided baseline data. These women were randomized into either the treatment group to receive the self-regulation intervention or to the usual-care control group. Participants’ physicians were blind to the assignment of their patients in this study. The failure of women to enroll in the study was attributable to problematic addresses or phone numbers or having moved their residence out of the study area (n = 774), death from all causes (n = 49), lack of interest (n = 307), belief that one did not have asthma (n = 159), and no stated reason or did not fit study criteria (n = 232).
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Frequencies of daytime and nighttime symptoms are two of the criteria used in the NAEPP guidelines18 to classify severity of asthma. Considering the seasonality of asthma, interview items tapped the number of days and nights by month and by season that the woman had asthma symptoms and had missed work or school because of asthma in the past 12 consecutive months. Questionnaire items mimicked a clinician’s queries of patients during the clinical encounter and have been used in previous studies.2324
Respondent self-reported ED visits and hospitalizations have been shown to correlate significantly with records of health-care institutions and to provide a reliable assessment of these types of health-care use.25 The self-reported recall data of the number of hospitalizations, ED visits, unscheduled urgent visits to a clinic, and scheduled clinic visits for asthma in the past 12 months were assessed through a series of items for the baseline and follow-up periods. To further verify the accuracy and reliability of the self-reports of asthma health-care use, medical record data for asthma ED visits and hospitalizations from the UM Data Warehouse during the corresponding time periods were collected to examine the correlations between the two sources of data.
Sex role-related and gender role-related queries were made that were related to symptoms and menstrual cycle, PMS, birth control pills, ERT, and urinary incontinence. Items were also tapped as asthma problems related to housework (eg, vacuuming, dusting, or cooking), washing or cleaning products, fragrances, cosmetics, and hair products, exposures through child care, and symptoms associated with social and sexual activity.
The Mini Asthma Quality of Life Questionnaire of Juniper and colleagues2627 was used to measure a woman’s quality of life. A scale of self-confidence for asthma management comprised 15 items that had previously been used by the investigators to assess a woman’s perception of her ability to carry out management tasks at home.28 To assess the level or phase of a woman’s self-regulation ability, items from the Zimmerman scale2324 were used to determine asthma-related practices, including the use of peak flow monitoring. Demographic data were also collected for use as covariates in the statistical models if needed.
Statistical Analysis
Sample size calculations using health-care use as the primary dependent variable determined that a final sample of 520 was needed to achieve 80% power at the 95% confidence level. A sample of this magnitude would allow testing of other study outcomes with a similar or higher level of confidence. Data from 608 women were available for intent-to-treat analysis at 1 year subsequent to baseline.
Descriptive analyses were conducted to examine randomization status (Table 2 ) and outcome variables (Table 3 ) at two time points for the groups. Descriptive analyses were then used to examine drop out data. There were no differences in dropouts due to demographic variables, disease severity, and important outcomes between the two groups. Hence, the generalized estimate equation (GEE) method, under the assumption of data missing completely at random, was used to further examine the statistically significant group differences for each outcome variable. The GEE method allows for the use of all available data at baseline (n = 808) and follow-up (n = 608).29 GEE linear regression analysis was used for continuous outcome variables, GEE logistic regression was used for binary variables, and GEE log-linear regression was used for count outcomes.2930 The GEE methods analyzed the baseline and follow-up data by including an indicator variable (time) for the follow-up, an indicator variable (treatment) for the intervention group and their interaction (treatment x time), and baseline covariates including demographics and other variables that were significant in initial models. In all final models, age, body mass index (BMI), and severity according to NAEPP classification at baseline were adjusted. The PROC GENMOD procedure (SAS; SAS Institute; Cary, NC) was used for fitting the models. For all models, an unstructured covariance matrix was used to account for the longitudinal nature of the data.30
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Results
Randomization Status
Table 2 shows that there were no statistically significant differences between the intervention and control groups at baseline for any demographic variable, for the percentage of women from specialty clinics or for medication use, and for the asthma severity classification based on nighttime symptoms when comparing the four categories of asthma severity (ie, mild intermittent, mild, moderate, and severe persistent) separately. As noted, when all women reporting persistent asthma were compared to those reporting mild intermittent asthma, the intervention group had significantly more women with persistent asthma than did the control group (51.5% vs 44.0%, respectively; p = 0.03).
Description of Group Outcomes
Table 3 describes group means with SDs at two time points, and differences in means between follow-up and baseline for all outcome variables.
Symptoms and Health-Care Use
Table 4
shows that at follow-up the overall reduction in the average number of nights in a month when women in the treatment group experienced symptoms was significantly greater than the reductions among control group women. There were no treatment or control differences related to the number of days with asthma symptoms.
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To the investigators’ knowledge, this is the first study to assess the effect on health outcomes of an asthma self-regulation intervention specifically addressing the perspective of female patients and their particular sex role-related and gender role-related management challenges. Symptom reduction is an important goal in asthma control, and the findings illustrate that the intervention significantly improved nighttime symptoms for program participants, but it had no significant effect on daytime symptoms. Nighttime symptoms are considered to be a marker of more severe disease, and as more women in the treatment group began the study with more persistent asthma, a reduction in these symptoms is a significant result. It may be that for nighttime symptoms more management was needed by more study women, and this is where the most change could be realized. Better self-regulation may have enabled women in the treatment group to find ways to minimize or avoid symptoms at night. Women in the treatment group experienced less school and work disruption due to asthma subsequent to their participation in the program. These results complement the reduction in nighttime symptoms for program participants and strengthen the argument that the control of symptoms at night can have an important effect on functioning for patients.
The positive outcomes for the women in the treatment group regarding ED visits and unscheduled office visits may be related to their improved self-regulation and self-confidence in managing their asthma in light of their physicians’ clinical recommendations. The lack of program benefit regarding hospital admissions may be a function of the program or may be associated with methodologic problems in assessing change when the number of observations is very small. To explore this variable further, we looked at the subset of women who had completed the program and compared them to women who had not completed the program. Hospitalization was 0.2 times less likely in women who completed the intervention sessions compared to women who did not complete the full program. Although this exploratory analysis has problems of self-selection bias, the results may indicate that women do not benefit regarding this outcome unless they complete all counseling sessions. It is also possible, as noted in previous asthma studies,2324 that significant differences in hospitalizations are found at more distant time points, for example, 18 to 24 months subsequent to baseline.
The consideration of sex and gender role factors as they relate to asthma management was one of the unique features of this study. In one fourth of these variables, differences were observed between the treatment and control groups. The differences identified were important, and were concerned with management during the menstrual cycle and with symptoms associated with sexual activity. Menstruation-linked asthma has been shown to be a significant predictor of urgent health-care use.31 Lack of change on other sex role-related and gender role-related items, however, does not mean that the focus on women’s issues was not a salient feature of success in reaching the outcomes observed. Although the intervention included specific sex and gender content, it also attempted in a broader sense to accommodate the particular experience, and voiced concerns arising from a woman’s efforts to manage her asthma given her initial level of self-regulation. This overall female-sensitive approach combined with a focus on capacity and confidence building likely explains the findings of the study.
The women in this randomized clinical trial were drawn from a large Midwestern, university-based clinical system. As a group they reflected a wide range of incomes, ages, education, and racial/ethnic backgrounds. They were not selected to represent a particular population. As a result, the study findings cannot be definitively generalized to all women or to a homogenous group of women. However, given the diversity of the sample, it is likely that the intervention would be successful with a general population of women seeking service in similar venues. The intervention itself can be easily replicated and introduced into a range of clinical settings.
Study Limitations
Though randomization processes were based on random length-permuted blocks, it happened that more women with persistent asthma were assigned to the treatment group. As noted, this fact could have made intervention results more difficult to achieve given that the women were sicker. Conversely, it could have provided more room for women to improve. This investigation did not use clinical measures such as FEV1 as the study was primarily concerned with symptoms and functioning. Spirometric measures may be useful in assessing the impact of such an intervention. Because of resource limitations, medical record data were only collected for a sample of women to assess the reliability of the self-reported recall data and health-care use records. Further, data regarding smoking status were not collected, and this variable could influence symptoms in smokers, though observation by clinical personnel suggests that smoking rates were low in this population.
Conclusion
Women in the treatment group receiving education focused on the particular management problems of a woman with asthma exhibited significant improvements in their symptoms, health-care use, quality of life, days of missed work or school, levels of self-regulation, and their self-confidence to manage asthma compared to women receiving conventional asthma education 1 year subsequent to the completion of the program.
There are implications for clinical practice in these findings. The consideration of a woman’s particular perspective and the experience of managing asthma and the sex-related and gender-related challenges that she faces appear to enrich a management intervention. Attention to these areas when counseling patients and their inclusion in programs offered in the clinical setting could enhance asthma outcomes for female patients.
This study observed patients for 1 year. Future work should examine the long-term benefits or any decay in benefits that may occur for women with asthma over time.
Acknowledgements
The authors would especially like to thank Jimmy Yu, Martha DeRoeck, Jane Burton, and Susan Dara for their contributions.
Footnotes
Abbreviations: BMI = body mass index; ED = emergency department; ERT = estrogen replacement therapy; GEE = generalized estimating equation; NAEPP = National Asthma Education and Prevention Program; PMS = premenstrual symptoms; UMHS = University of Michigan Health System
The research was supported by grant 1 R18 HL60884–01 from the Division of Lung Diseases of the National Heart, Lung, and Blood Institute.
The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
Received for publication November 2, 2006. Accepted for publication March 6, 2007.
References
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