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Clinical Investigations: ASTHMA |

Risk Behaviors and Health-Related Quality of Life Among Adults With Asthma*: The Role of Mental Health Status FREE TO VIEW

Tara W. Strine, MPH; Earl S. Ford, MD, MPH; Lina Balluz, ScD; Daniel P. Chapman, PhD, MSc; Ali H. Mokdad, PhD
Author and Funding Information

*From the Centers for Disease Control and Prevention, Atlanta, GA.

Correspondence to: Tara W. Strine, MPH, Division of Adult and Community Health, Centers for Disease Control and Prevention, 4770 Buford Hwy NE, Mailstop K-66, Atlanta, GA 30341; e-mail: tws2@cdc.gov



Chest. 2004;126(6):1849-1854. doi:10.1378/chest.126.6.1849
Text Size: A A A
Published online

Background: Previous research indicates that asthma is strongly associated with depressive disorders. Depression among persons with asthma is associated with poor adherence to medication regimens, more severe asthma, and poorer disease outcomes. The objective of our study was to examine the association of frequent mental distress (FMD) [ie, ≥ 14 days in the past 30 days in which respondents reported that their mental health was not good] with modifiable risk behaviors (ie, smoking, physical inactivity, and obesity) and health-related quality of life among adults with asthma.

Methods: The Behavioral Risk Factor Surveillance System is an ongoing, state-based survey that is conducted by random-digit dialing of noninstitutionalized US adults aged ≥ 18 years. In 2001, all 50 states administered the asthma and risk behavior questionnaires (15,080 questionnaires). A total of 12 states administered the health-related quality-of-life questionnaire (3,226 questionnaires). We estimated prevalences, 95% confidence intervals, odds ratios, and adjusted odds ratios (AORs) using a statistical software program to account for the complex survey design.

Results: The prevalence of FMD among adults with asthma was 18.8%. After adjusting for sociodemographic characteristics, the overall associations between smoking and FMD (AOR, 1.9), and between physical inactivity and FMD (AOR, 1.7) were statistically significant. In addition, among those with asthma, persons with FMD were significantly more likely than those without FMD to report fair/poor general health, frequent physical distress, frequent activity limitations, frequent anxiety, and frequent sleeplessness.

Conclusions: FMD is highly prevalent among persons with asthma, suggesting an apparent synergistic effect of these two conditions. The assessment of the mental health status of persons with asthma by health-care providers appears to be warranted and may prevent the emergence of risk behaviors yielding deleterious effects on the management of this disease.

Figures in this Article

In 2001, approximately 7.2% of US adults reported having a current diagnosis of asthma, a chronic inflammatory pulmonary disease that has increased in prevalence each year since 1980.12 In the United States in 2000, asthma accounted for 4,487 deaths, approximately 465,000 hospitalizations, an estimated 1.8 million visits to emergency departments, and approximately 10.4 million physician visits.23 In 1998, the estimated cost of asthma in the United States was $12.7 billion.4

Asthma can impair health-related quality of life (HRQOL)57 and is consistently associated with an increased prevalence of depressive disorders.811 Depression among those with asthma is associated with poor adherence to medication regimens,1213 more severe asthma, and poorer disease outcomes.8,11 Considerable research has examined the impact of depressive symptoms on asthma. However, to our knowledge, previous research has not assessed the association between depressive symptoms and asthma-related risk behaviors among adults with asthma. These associations may indicate a potential pathway linking depressive symptoms to poor asthma outcomes. To better address this issue, we analyzed data from the Behavioral Risk Factor Surveillance System (BRFSS) to determine whether frequent mental distress (FMD) [ie, ≥ 14 days in the past 30 days in which respondents reported that their mental health was not good] among persons with asthma was associated with various risk behaviors and impaired HRQOL.

The BRFSS is an ongoing, state-based telephone survey conducted by the random-digit dialing of noninstitutionalized US adults. BRFSS monitors the prevalence of key health-related and safety-related behaviors and characteristics.14In 2001, trained interviewers in the 50 states and the District of Columbia administered identical questionnaires about asthma over the telephone to an independent probability sample of adults aged ≥ 18 years. Data from all states and areas were pooled to produce national estimates. BRFSS methods, including the weighting procedure, have been described elsewhere.15

To be classified as having asthma, the respondent must have answered “yes” to the following two questions: “Have you ever been told by a doctor, nurse, or other health professional that you had asthma?”; and “Do you still have asthma?”

To assess the prevalence of FMD in persons with asthma, we used responses to the question, “Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?” The mentally unhealthy days measure correlates most strongly with the mental health, role emotion, and mental component summary scales of the Medical Outcomes Study Short Form 3616and correlates acceptably with the clinically validated Center for Epidemiologic Studies of Depression scale.17Respondents who reported ≥ 14 mentally unhealthy days in the past 30 days were classified as having FMD.18 As in other BRFSS studies,5,1820 this 14-day minimum period was selected because it is consistent with the diagnostic criteria for major depressive disorder specified in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision.21 Although the measures for mentally unhealthy days and FMD have been shown to be valid indicators of the perceived burden of mental distress in patients with common mental disorders,2224 they have not yet been tested as a screen for a diagnosable mental illness.

As smoking, physical inactivity, and obesity have been associated with poorer asthma-related outcomes,2527 we examined the relationship between these risk factors and FMD among persons with asthma. Respondents were considered to be current smokers if they had smoked at least 100 cigarettes in their lifetime and were currently smokers. Those who formerly smoked or never smoked were considered to be nonsmokers. Respondents who reported that they had not participated in any physical activities or exercise, such as running, calisthenics, golf, gardening, or walking for exercise during the past 30 days were categorized as physically inactive. Finally, body mass index was calculated as weight in kilograms divided by the square of height in meters. Patients were considered obese if their body mass index was ≥ 30.

Data were available for 204,359 participants in the 50 states and the District of Columbia who answered both asthma questions. We excluded those persons without current asthma (188,615 persons), those who did not answer the mentally unhealthy days question (342 persons), and those without complete information for study variables (322 persons). Data on the remaining 15,080 respondents were analyzed.

In addition, we examined the HRQOL of persons with asthma by FMD status. In 2001, trained interviewers administered standardized quality-of-life questions in a total of 12 states (ie, Alaska, Arizona, Delaware, Georgia, Maryland, Minnesota, Nebraska, New Jersey, Ohio, Tennessee, Utah, and Virginia) and the District of Columbia.

We used five HRQOL questions with demonstrated validity and reliability for population health surveillance.28 General health was assessed by asking the respondent to rate their health from poor to excellent. The remaining four questions are referenced to the preceding 30 days, as follows: “How many days was your physical health, which includes physical illness or injury, not good? (physical distress),”; “How many days did you feel worried, tense, or anxious? (anxiety),”; “How many days have you felt you did not get enough rest or sleep? (sleeplessness),”; and “How many days did poor physical or mental health keep you from doing your usual activities, such as self-care, work, or recreation? (activity limitations).” Responses were categorized by the duration of impaired health (<14 days and ≥ 14 days [frequent]) in each domain. Data were available for 3,226 respondents in the 12 states.

We estimated prevalences, 95% confidence intervals (CIs), odds ratios, and adjusted odds ratios (AORs) in all analyses by using a statistical software program (SUDAAN, release 8.0.0; Research Triangle Institute; Research Triangle Park, NC) to account for the complex survey design. Covariates in the adjusted models include sex, age, race or ethnicity, education, marital status, and employment status.

The prevalence of FMD was 18.8% (95% CI, 17.7 to 19.9%) among adults with asthma. As Table 1 indicates, persons reporting FMD were significantly more likely to be women than men, and to be < 65 years old rather than ≥ 65 years. Hispanics with asthma were significantly more likely to report FMD than white non-Hispanics, as were respondents with less than a high school education relative to those with greater than a high school education. FMD was significantly more prevalent among respondents with asthma who were previously married or never married than those who were currently married, as were those who were unemployed, unable to work, or retired compared to those who were employed.

Among adults with asthma, the age-adjusted likelihood of each of the three adverse health behaviors (ie, smoking, obesity, and physical inactivity) was greater among adults with FMD compared to those without FMD (smoking AOR, 2.3; obesity AOR, 1.5; and physical inactivity AOR, 2.3) [Table 2] . Further adjustment for sex, race and ethnicity, education, marital status, and employment status attenuated the associations of FMD with smoking, obesity, and physical inactivity. However, the relationships between smoking and FMD, and between physical inactivity and FMD remained significant.

Not only were persons with FMD more likely to engage in adverse health behaviors than were those without FMD, but after adjustment for the sociodemographic characteristics, they were also more likely to engage in two or more of the three risk behaviors (AOR, 1.9; 95% CI, 1.6 to 2.3).

Figure 1 illustrates that among persons with asthma, those with FMD were significantly more likely than those without FMD to report fair/poor general health (with FMD: 55.6%; 95% CI, 49.8 to 61.5%; without FMD: 26.0%; 95% CI, 23.4 to 28.6%), frequent physical distress (with FMD: 44.3%; 95% CI, 38.4 to 50.1%; without FMD: 16.3%; 95% CI, 14.0 to 18.6%), frequent activity limitations (with FMD: 41.9%; 95% CI, 36.1 to 47.6%; without FMD: 7.4%; 95% CI, 6.0 to 8.8%), frequent sleeplessness (with FMD: 65.1%; 95% CI, 59.1 to 71.0%; without FMD: 37.4%; 95% CI, 34.5 to 40.2%), and frequent anxiety (with FMD: 73.3%; 95% CI, 67.9 to 78.7%; without FMD: 15.4%; 95% CI, 13.4 to 17.4%).

Persons with asthma were twice as likely to report FMD as those without asthma (18.8% and 9.3%, respectively) [data not shown]. Depressive symptoms have been previously identified as barriers to the diagnosis and management of asthma29and are frequently undiagnosed.3032 Therefore, it is important that physicians are cognizant of the association between asthma and depressive symptoms, and that they develop comprehensive treatment plans for the medical management of patients with both conditions when they coexist.33

Lehrer et al34 have suggested that asthma and depressive disorders may intensify each other through direct psychophysiologic mediation, nonadherence to medical regimens, and exposure to asthma triggers. Our research suggests that among persons with asthma, those with FMD are more likely than those without FMD to engage in behaviors that could exacerbate their asthma. Specifically, those with FMD were significantly more likely than those without FMD to be current smokers and to be physically inactive, after adjusting for sociodemographic characteristics. In addition, the age-adjusted odds of obesity was significantly higher for those with FMD than for those without FMD. Among persons with asthma, those with FMD were also more likely than those without FMD to report a constellation of risk behaviors potentially deleterious to the management of asthma.

Cigarette smoking is a risk factor for morbidity and mortality among persons with asthma by triggering asthma attacks and producing more severe attacks.25Exercise, on the other hand, improves both physiologic components of the disease (ie, improved respiratory functioning and maintenance of a healthy weight) and psychological components of the disease (ie, social and mental well-being, self image, HRQOL, and activities of daily living).27 Although persons with severe asthma and those with exercise-induced asthma may be less likely to participate in physical activity, with proper treatment most asthmatic adults are able to engage in recommended levels of activity.26In addition, exercise can help to achieve a healthy weight, which is particularly important to those with asthma, as obesity may be causally related to asthma or may contribute to more severe disease.27

There are several limitations to our study. First, BRFSS is a telephone survey, so it excludes the homeless, residents in institutionalized settings, and persons of low socioeconomic status who have no telephones. Second, those with impaired physical or mental capacity might not be able to complete the survey. Third, all physical and mental health measures were self-reported and were not validated by clinical examination. Fourth, the BRFSS does not contain questions about the severity of asthma, visits to physicians or emergency departments, or hospitalizations. Fifth, because the HRQOL subanalysis was based on data from only 12 states and the District of Columbia, this portion of our analysis may not be representative of the entire country. Finally, the BRFSS self-reported asthma questions have not been tested for reliability and validity; however, other studies have suggested that the agreement between self-reported asthma and medical records is substantial.3536

Due to the high prevalence of depressive symptoms among persons with asthma, and the interactive effect of asthma and depression combined, physicians need to carefully assess the mental health status of persons with asthma and, when needed, involve mental health professionals in the treatment and care of those presenting substantial depressive symptomology. There are a number of depression screening instruments for the clinical setting, including the nine-item, self-administered patient health questionnaire.37 In addition to making criteria-based diagnoses of depressive disorders, the nine-item, self-administered patient health questionnaire is also a reliable and valid measure of depressive severity, which could aid the clinician in identifying patients with depression potentially meriting referral to a provider of mental health care.

Abbreviations: AOR = adjusted odds ratio; BRFSS = Behavioral Risk Factor Surveillance System; CI = confidence interval; FMD = frequent mental distress; HRQOL = health-related quality of life

Table Graphic Jump Location
Table 1. Prevalence and Odds of FMD Among Adults Aged ≥ 18 Years With Current Asthma, by Demographic Characteristics, 2001
* 

Unweighted.

 

Values in parentheses are 95% CIs.

 

Asian, non-Hispanic; Native Hawaiian/Pacific Islander, non-Hispanic; American Indian/Alaska Native, non-Hispanic; other race, non-Hispanic; and multirace, non-Hispanic.

§ 

Includes those divorced, widowed or separated.

 

Includes those never married or member of an unmarried couple.

Table Graphic Jump Location
Table 2. Crude and AORs for Adverse Health Behaviors in People With Current Asthma Reporting FMD vs Those Not Reporting FMD
* 

Values in parentheses are 95% CIs.

 

Adjusted by sex, age, race and ethnicity, education, marital status, and employment status.

Figure Jump LinkFigure 1. Unadjusted prevalence rates for HRQOL indicators among adults aged ≥ 18 year with asthma among those reporting FMD (black bars) or not reporting FMD (light gray bars). The data are from 3,226 respondents to the BRFSS telephone survey, 2001.Grahic Jump Location
Rhodes, L, Moorman, JE, Redd, SC, et al (2003) Self-reported asthma prevalence and control among adults: United States, 2001.MMWR Morb Mortal Wkly Rep52,381-384. [PubMed]
 
Mannino, DM, Homa, DM, Akinbami, LJ, et al Surveillance of asthma: United States, 1980–1999.MMWR Morb Mortal Wkly Rep2002;51,1-13
 
Centers for Disease Control and Prevention. National Center for Health Statistics: asthma prevalence, health care use and mortality, 2000–2001. Available at: http://www.cdc.gov/nchs/products/pubs/pubd/hestats/asthma/asthma.htm. Accessed May 26, 2004.
 
Weiss, KB, Sullivan, SD The health economics of asthma and rhinitis: 1. Assessing the economic impact.J Allergy Clin Immunol2001;107,3-8. [CrossRef] [PubMed]
 
Ford, ES, Mannino, DM, Homa, DM, et al Self-reported asthma and health-related quality of life.Chest2003;123,119-127. [CrossRef] [PubMed]
 
Thoonen, BP, Schermer, TR, van den Boom, G, et al Self-management of asthma in general practice, asthma control and quality of life: a randomized controlled trial.Thorax2003;58,30-36. [CrossRef] [PubMed]
 
Erickson, SR, Christian, RD, Jr, Kirking, DM, et al Relationship between patient and disease characteristics, and health-related quality of life in adults with asthma.Respir Med2002;96,450-460. [CrossRef] [PubMed]
 
Goldney, RD, Ruffin, R, Fisher, LJ, et al Asthma symptoms associated with depression and lower quality of life: a population survey.Med J Aust2003;178,437-441. [PubMed]
 
Rimington, LD, Davies, DH, Lowe, D, et al Relationship between anxiety, depression, and morbidity in adult asthma patients.Thorax2001;56,266-271. [CrossRef] [PubMed]
 
Janson, C, Bjornsson, E, Hetta, J, et al Anxiety and depression in relation to respiratory symptoms and asthma.Am J Respir Crit Care Med1994;149,930-934. [PubMed]
 
Mancuso, CA, Rincon, M, McCulloch, CE, et al Self-efficacy, depressive symptoms, and patient’s expectation predict outcomes in asthma.Med Care2001;39,1326-1338. [CrossRef] [PubMed]
 
Cluley, S, Cochrane, GM Psychological disorder in asthma is associated with poor control and poor adherence to inhaled steroids.Respir Med2001;95,37-39. [CrossRef] [PubMed]
 
Cochrane, GM Compliance and outcomes in patients with asthma.Drugs1996;52(suppl 6),12-19. [PubMed]
 
Centers for Disease Control and Prevention. Behavioral risk factor surveillance system user’s guide. Available at: http://www.cdc.gov/brfss/technical_infodata/usersguide.htm. Accessed May 26, 2004.
 
Mokdad, AH, Stroup, DF, Giles, WH Public health surveillance for behavioral risk factors in a changing environment: recommendations from the Behavioral Risk Factor Surveillance Team. MMWR Morb Mortal Wkly Rep. 2003;;52(RR-9)
 
Newschaffer, CJ. Validation of BRFSS HRQOL measures in a statewide sample. 1998; US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. Atlanta, GA:.
 
Albert, SM. Validation of BRFSS QOL items: Harlem Prostate Screening Project. 1997; Columbia University College of Physicians and Surgeons. New York, NY:.
 
Centers for Disease Control and Prevention. Self-reported frequent mental distress among adults: United States, 1993–1996.JAMA1998;279,1772-1773. [CrossRef] [PubMed]
 
Ford, ES, Moriarty, DG, Zack, MM, et al Self-reported body mass index and health-related quality of life: findings from the Behavioral Risk Factor Surveillance System.Obes Res2001;9,21-31. [CrossRef] [PubMed]
 
Ahluwalia, IB, Holtzman, D, Mack, KA, et al Health-related quality of life among women of reproductive age: Behavioral Risk Factor Surveillance System (BRFSS), 1998–2001.J Womens Health2003;12,5-9. [CrossRef]
 
American Psychiatric Association. Diagnostic and statistical manual of mental disorders, text revision 4th ed.2000 American Psychiatric Association. Washington, DC:
 
Simon, P, Lightstone, A, Zeng, Z, et al Health-related quality of life—Los Angeles County, California, 1999.MMWR Morb Mortal Wkly Rep2001;50,556-559. [PubMed]
 
Dominick, KL, Ahern, FM, Gold, CH, et al Health-related quality of life among older adults with activity-limiting health conditions.J Ment Health Aging2003;9,43-53
 
Foundation for Accountability, Robert Wood Johnson Foundation. A portrait of the chronically ill in America, 2001 (April 2002). Available at: http://www.rwjf.org/publications/publicationsPdfs/report_chronic_illness.pdf. Accessed February 17, 2004.
 
Althuis, MD, Sexton, M, Prybylski, D Cigarette smoking and asthma symptom severity among adult asthmatics.J Asthma1999;36,257-264. [CrossRef] [PubMed]
 
Ford, ES, Heath, GW, Mannino, DM, et al Leisure-time physical activity patterns among US adults with asthma.Chest2003;124,432-437. [CrossRef] [PubMed]
 
Ford, ES, Mannino, DM, Redd, SC, et al Weight-loss practices and asthma: findings from the Behavioral Risk Factor Surveillance System.Obesity Res2003;11,81-86. [CrossRef]
 
Moriarty, DG, Zack, MM, Kobau, R The Centers for Disease Control and Prevention’s healthy days measures: population tracking of perceived physical and mental health over time.Health Qual Life Outcomes2003;1,37-45. [CrossRef] [PubMed]
 
Rietveld, S, Creer, TL Psychiatric factors in asthma: implications for diagnosis and therapy.Am J Respir Med2003;2,1-10. [CrossRef] [PubMed]
 
Brown, ES, Khan, DA, Mahadi, S Psychiatric diagnosis in inner city outpatients with moderate to severe asthma.Int J Psychiatry Med2000;30,319-327. [PubMed]
 
Mancuso, CA, Peterson, MGE, Charlson, ME Effects of depressive symptoms on health-related quality of life in asthma patients.J Gen Intern Med2000;15,301-310. [CrossRef] [PubMed]
 
Ford, DE Managing patients with depression: is primary care up to the challenge [editorial]?J Gen Intern Med2000;15,344-345. [CrossRef] [PubMed]
 
Bosley, CM, Corden, ZN, Cochrane, GM Psychological factors and asthma.Respir Med1996;90,453-457. [CrossRef] [PubMed]
 
Lehrer, P, Feldman, J, Giardino, N, et al Psychosocial aspects of asthma.J Consult Clin Psychol2002;70,691-711. [CrossRef] [PubMed]
 
Harlow, SD, Linet, MS Agreement between questionnaire data and medical records: the evidence for accuracy of recall.Am J Epidemiol1989;129,233-248. [PubMed]
 
Linet, MS, Harlow, SD, McLaughlin, JK, et al A comparison of interview data and medical records for previous medical conditions and surgery.J Clin Epidemiol1989;42,1207-1213. [CrossRef] [PubMed]
 
Kroenke, K, Spitzer, R, Williams, JBW The PHQ-9: validity of a brief depression severity measure.J Gen Intern Med2001;16,606-613. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1. Unadjusted prevalence rates for HRQOL indicators among adults aged ≥ 18 year with asthma among those reporting FMD (black bars) or not reporting FMD (light gray bars). The data are from 3,226 respondents to the BRFSS telephone survey, 2001.Grahic Jump Location

Tables

Table Graphic Jump Location
Table 1. Prevalence and Odds of FMD Among Adults Aged ≥ 18 Years With Current Asthma, by Demographic Characteristics, 2001
* 

Unweighted.

 

Values in parentheses are 95% CIs.

 

Asian, non-Hispanic; Native Hawaiian/Pacific Islander, non-Hispanic; American Indian/Alaska Native, non-Hispanic; other race, non-Hispanic; and multirace, non-Hispanic.

§ 

Includes those divorced, widowed or separated.

 

Includes those never married or member of an unmarried couple.

Table Graphic Jump Location
Table 2. Crude and AORs for Adverse Health Behaviors in People With Current Asthma Reporting FMD vs Those Not Reporting FMD
* 

Values in parentheses are 95% CIs.

 

Adjusted by sex, age, race and ethnicity, education, marital status, and employment status.

References

Rhodes, L, Moorman, JE, Redd, SC, et al (2003) Self-reported asthma prevalence and control among adults: United States, 2001.MMWR Morb Mortal Wkly Rep52,381-384. [PubMed]
 
Mannino, DM, Homa, DM, Akinbami, LJ, et al Surveillance of asthma: United States, 1980–1999.MMWR Morb Mortal Wkly Rep2002;51,1-13
 
Centers for Disease Control and Prevention. National Center for Health Statistics: asthma prevalence, health care use and mortality, 2000–2001. Available at: http://www.cdc.gov/nchs/products/pubs/pubd/hestats/asthma/asthma.htm. Accessed May 26, 2004.
 
Weiss, KB, Sullivan, SD The health economics of asthma and rhinitis: 1. Assessing the economic impact.J Allergy Clin Immunol2001;107,3-8. [CrossRef] [PubMed]
 
Ford, ES, Mannino, DM, Homa, DM, et al Self-reported asthma and health-related quality of life.Chest2003;123,119-127. [CrossRef] [PubMed]
 
Thoonen, BP, Schermer, TR, van den Boom, G, et al Self-management of asthma in general practice, asthma control and quality of life: a randomized controlled trial.Thorax2003;58,30-36. [CrossRef] [PubMed]
 
Erickson, SR, Christian, RD, Jr, Kirking, DM, et al Relationship between patient and disease characteristics, and health-related quality of life in adults with asthma.Respir Med2002;96,450-460. [CrossRef] [PubMed]
 
Goldney, RD, Ruffin, R, Fisher, LJ, et al Asthma symptoms associated with depression and lower quality of life: a population survey.Med J Aust2003;178,437-441. [PubMed]
 
Rimington, LD, Davies, DH, Lowe, D, et al Relationship between anxiety, depression, and morbidity in adult asthma patients.Thorax2001;56,266-271. [CrossRef] [PubMed]
 
Janson, C, Bjornsson, E, Hetta, J, et al Anxiety and depression in relation to respiratory symptoms and asthma.Am J Respir Crit Care Med1994;149,930-934. [PubMed]
 
Mancuso, CA, Rincon, M, McCulloch, CE, et al Self-efficacy, depressive symptoms, and patient’s expectation predict outcomes in asthma.Med Care2001;39,1326-1338. [CrossRef] [PubMed]
 
Cluley, S, Cochrane, GM Psychological disorder in asthma is associated with poor control and poor adherence to inhaled steroids.Respir Med2001;95,37-39. [CrossRef] [PubMed]
 
Cochrane, GM Compliance and outcomes in patients with asthma.Drugs1996;52(suppl 6),12-19. [PubMed]
 
Centers for Disease Control and Prevention. Behavioral risk factor surveillance system user’s guide. Available at: http://www.cdc.gov/brfss/technical_infodata/usersguide.htm. Accessed May 26, 2004.
 
Mokdad, AH, Stroup, DF, Giles, WH Public health surveillance for behavioral risk factors in a changing environment: recommendations from the Behavioral Risk Factor Surveillance Team. MMWR Morb Mortal Wkly Rep. 2003;;52(RR-9)
 
Newschaffer, CJ. Validation of BRFSS HRQOL measures in a statewide sample. 1998; US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. Atlanta, GA:.
 
Albert, SM. Validation of BRFSS QOL items: Harlem Prostate Screening Project. 1997; Columbia University College of Physicians and Surgeons. New York, NY:.
 
Centers for Disease Control and Prevention. Self-reported frequent mental distress among adults: United States, 1993–1996.JAMA1998;279,1772-1773. [CrossRef] [PubMed]
 
Ford, ES, Moriarty, DG, Zack, MM, et al Self-reported body mass index and health-related quality of life: findings from the Behavioral Risk Factor Surveillance System.Obes Res2001;9,21-31. [CrossRef] [PubMed]
 
Ahluwalia, IB, Holtzman, D, Mack, KA, et al Health-related quality of life among women of reproductive age: Behavioral Risk Factor Surveillance System (BRFSS), 1998–2001.J Womens Health2003;12,5-9. [CrossRef]
 
American Psychiatric Association. Diagnostic and statistical manual of mental disorders, text revision 4th ed.2000 American Psychiatric Association. Washington, DC:
 
Simon, P, Lightstone, A, Zeng, Z, et al Health-related quality of life—Los Angeles County, California, 1999.MMWR Morb Mortal Wkly Rep2001;50,556-559. [PubMed]
 
Dominick, KL, Ahern, FM, Gold, CH, et al Health-related quality of life among older adults with activity-limiting health conditions.J Ment Health Aging2003;9,43-53
 
Foundation for Accountability, Robert Wood Johnson Foundation. A portrait of the chronically ill in America, 2001 (April 2002). Available at: http://www.rwjf.org/publications/publicationsPdfs/report_chronic_illness.pdf. Accessed February 17, 2004.
 
Althuis, MD, Sexton, M, Prybylski, D Cigarette smoking and asthma symptom severity among adult asthmatics.J Asthma1999;36,257-264. [CrossRef] [PubMed]
 
Ford, ES, Heath, GW, Mannino, DM, et al Leisure-time physical activity patterns among US adults with asthma.Chest2003;124,432-437. [CrossRef] [PubMed]
 
Ford, ES, Mannino, DM, Redd, SC, et al Weight-loss practices and asthma: findings from the Behavioral Risk Factor Surveillance System.Obesity Res2003;11,81-86. [CrossRef]
 
Moriarty, DG, Zack, MM, Kobau, R The Centers for Disease Control and Prevention’s healthy days measures: population tracking of perceived physical and mental health over time.Health Qual Life Outcomes2003;1,37-45. [CrossRef] [PubMed]
 
Rietveld, S, Creer, TL Psychiatric factors in asthma: implications for diagnosis and therapy.Am J Respir Med2003;2,1-10. [CrossRef] [PubMed]
 
Brown, ES, Khan, DA, Mahadi, S Psychiatric diagnosis in inner city outpatients with moderate to severe asthma.Int J Psychiatry Med2000;30,319-327. [PubMed]
 
Mancuso, CA, Peterson, MGE, Charlson, ME Effects of depressive symptoms on health-related quality of life in asthma patients.J Gen Intern Med2000;15,301-310. [CrossRef] [PubMed]
 
Ford, DE Managing patients with depression: is primary care up to the challenge [editorial]?J Gen Intern Med2000;15,344-345. [CrossRef] [PubMed]
 
Bosley, CM, Corden, ZN, Cochrane, GM Psychological factors and asthma.Respir Med1996;90,453-457. [CrossRef] [PubMed]
 
Lehrer, P, Feldman, J, Giardino, N, et al Psychosocial aspects of asthma.J Consult Clin Psychol2002;70,691-711. [CrossRef] [PubMed]
 
Harlow, SD, Linet, MS Agreement between questionnaire data and medical records: the evidence for accuracy of recall.Am J Epidemiol1989;129,233-248. [PubMed]
 
Linet, MS, Harlow, SD, McLaughlin, JK, et al A comparison of interview data and medical records for previous medical conditions and surgery.J Clin Epidemiol1989;42,1207-1213. [CrossRef] [PubMed]
 
Kroenke, K, Spitzer, R, Williams, JBW The PHQ-9: validity of a brief depression severity measure.J Gen Intern Med2001;16,606-613. [CrossRef] [PubMed]
 
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