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Assessment of Asthma Control in a General Population of Asthmatics*

Posted on: Thursday, 9 February 2006, 06:00 CST

By LeNoir, Michael; Williamson, Alyssa; Stanford, Richard H; Stempel, David A

Key words: Asthma - Asthma control - Asthma disease severity - Asthma therapy - Lung function - Spirometry

ABSTRACT

Background: Asthma control is typically assessed by review of symptoms and measurement of airflow obstruction by clinic spirometry or outpatient peak flow. Recently the role of questionnaires to assess asthma control has been discussed.

Study objective: To investigate the frequency of asthma control in the general population using the Asthma Control Test ([ACTJ, ACT is a trademark of QualityMetric, Lincoln RI) and force expiratory volume in one second (FEV^sub 1^).

Research design and methods: Subjects with self-reported physician diagnosed asthma or use of asthma prescription medications attending community or sporting events were asked to complete the five-question ACT and to perform spirometry. Subjects with an ACT score of ≤ 19 and/or an FEV^sub 1^ of < 80% predicted were classified as having not well controlled (NWC) asthma.

Results: 2702 subjects completed both the ACT and spirometry. ACT scores ≤ 19 were recorded in 27% and FEV^sub 1^ < 80% predicted was noted in 26% of subjects evaluated. ACT and/or lung function was in the NWC range for 43% of subjects; 10% of subjects had both an ACT score ≤ 19 and an FEV^sub 1^ < 80% and 16-17% had either an ACT score ≤ 19 or a FEV1 < 80%.

Conclusion: A considerable portion (43%) of subjects with self- reported asthma in the general population was identified with NWC. In addition, the use of ACT and spirometry were equally effective methods to identify NWC asthma.

Introduction

One of the primary challenges in the management of patients with persistent asthma is the identification of patients with not well- controlled asthma (NWC) who may benefit from initiation or modification of their asthma treatment plan. Several approaches have been proposed. The traditional strategy employs the disease severity definitions that are part of the National Asthma Education Prevention Program (NAEPP)1. Disease severity determination is based on the level of symptoms, day or night, exacerbations and lung function at the time of presentation. Therapy can then be altered in a stepwise approach depending on response to treatment and exposure to triggers. An alternative method proposed is to assess asthma control2-5 as the

primary criteria for therapeutic decision making. The paradigm shift to disease control was first articulated by Cockcroft and Swystun2 who defined asthma control as achieving the goals of asthma care established by NAEPP1 and Global Initiative for Asthma (GINA)6, and proposed that the majority of patients of all disease severities should have the expectation to achieve control of their asthma. Asthma control commonly varies over days and weeks. It reflects changes in pulmonary dynamics due to exposure to ubiquitous viral infections, allergens and air pollutants as well as adherence to the medical treatment plan. Asthma severity, alternatively, is a more constant feature of the disease that may be related to disease duration, genetics, prolonged environmental exposures and intrinsic features of the disease. Disease severity, as a guide to asthma therapy, is confounded by the paradox of the patient with mild disease in poor control because of episodic treatment and the patient with severe disease in good control with the use of consistent controller medications. Therefore, both asthma disease severity and disease control should be considered in determining pharmacotherapy in order to optimize long-term disease management.

Patients with asthma frequently underestimate their level of disease control. An international study that assessed the patients' perceptions of control demonstrated that there is a discrepancy between the patients' global awareness of asthma control and their reporting of specific symptoms of asthma7. The authors state that 32- 49% of subjects with self-reported symptoms of severe asthma and 39- 70% with symptoms consistent with moderate asthma perceived that their respiratory disease was well or completely controlled. Further, there was not a consistent association of appropriate medication use recommended by guidelines and the patients' reported disease severity. Patient under-reporting of symptoms increases the likelihood that physicians may not properly identify active disease that warrants treatment. Wolfenden and colleagues identified that if a physician diagnosed a lower level of disease severity, the result was the under-treatment of asthma8. Similar findings were observed in a pediatric assessment by Halterman and coworkers9. When disease control is accurately assessed patients are more likely to be prescribed appropriate medications8.

NAEPP1 and GINA6 have established goals of asthma therapy that include the reduction or elimination of symptoms, night-time sleep disruption, activity level without restrictions due to asthma and no exacerbations while achieving normal or near normal lung functions. The goals should be achieved with minimal therapeutic adverse effects and gain the satisfaction of both the patient and family. Appropriate patient assessment is needed to achieve these goals. Spirometry remains an important screening tool for asthma as well as a parameter for assessing disease severity. However, studies have demonstrated that spirometry, especially forced expiratory volume in one second (FEV^sub 1^), does not always correlate with the level of symptom control10-14.

Recently, attention has focused on the assessment of asthma control with the use of one of three validated questionnaires, Asthma Control Test ([ACT], ACT is a trademark of QualityMetric, Lincoln RI)3, Asthma Control Questionnaire (ACQ)4 and Asthma Therapy Evaluation Questionnaire (ATAQ)5. These three control questionnaires all evaluate activity level, sleep disturbance, and the need for rescue albuterol. Shortness of breath3,4 and global assessment of asthma control3,5 status is appraised in two of these instruments. The ACT has been validated as an instrument that can effectively track asthma control status over time15. These questionnaires are designed as easy to use screening tools to assess and track the multifaceted spectrum of asthma disease control. The present study was designed as a descriptive study of ACT and spirometry independently and together as screening tools for determining asthma control.

Methods

The assessment of lung health was part of general health screening conducted at community based (i.e., a Spring festival, ethnic neighborhood gatherings, general health screening fairs and American Lung Association sponsored walks) and at large regional sporting events (auto races). Subjects volunteered for a general healthcare screening, signed an informed consent form detailing the use and distribution of the de-identified information prior to the health assessment and completed a brief health history questionnaire. If they answered the following question affirmatively: 'Have you ever been told by a physician that you had asthma or have you taken medication for asthma?', they were asked to answer an additional survey that included demographic information, ethnicity, current use of asthma medication, history of other lung disease and a global assessment of general health status. Subjects were additionally requested to complete the ACT (see the Appendix). This validated, five-question tool utilizes a 1-5 scale with higher scores reflecting better asthma control. Only questionnaires with responses to all five queries were tabulated. Scores ≤ 19 have been associated with asthma NWC3.

Spirometry was also performed at all sites using a Welsh Alien/ Schiller SP-2 spirometer. At each screening site there was a trained technician who administered the spirometry. The technicians were predominantly respiratory therapists and nurses. Only spirometry measurements that met American Thoracic Society criteria16 were included for assessment. Knudson normal values were utilized for the analysis17. Patients' asthma was considered controlled if their FEV^sub 1^ was greater than or equal to 80% predicted and their ACT score was 20 or more.

At community screening sites subjects completed paper surveys and data were entered into the database by hand, and participants received a copy of their informed consent, completed questionnaire and spirometry results. Informed consent forms were separate from the questionnaire; therefore, no personally identifiable health information was relayed. Data were collected in an appropriate fashion and compliant with Health Insurance Portability and Accountability Act (HIPAA) procedures pertaining to safe transfer, storage and protection of all information collected at screening events.

Data were captured electronically at the sporting events. Participants initially answered a questionnaire and the ACT at computer terminals. These data were stored on a 'swipe card'. Subjects were then directed to a screening station for spirometry. The swipe card was used again at the screening station to collect testing outcome results. Data were then uploaded to a secure/ private database from both types of screening sites. Participants received a printout of their results upon leaving the health screening area that advised them to speak to their physicians if their asthma was considered NWC by either ACT o\r spirometry.

Statistical analysis

Categorical variables were summarized using frequency distributions (counts and proportions) and continuous variables were summarized with descriptive statistics (means and standard deviations). Differences in proportions between the well-controlled asthma group and not well-controlled asthma group were tested using chi-square tests. Mean differences between the wellcontrolled group and not well-controlled group were tested using unpaired t-tests. All tests were two-sided and were not adjusted for multiple comparisons.

Table 1. Control versus not well-controlled asthma based on FEV^sub 1^ and ACT

Results

Over 29 000 subjects from 223 locations participated in the screenings. A total of 4464 (15.8%) of these subjects answered that they had a physician diagnosis of asthma or had used asthma medications; 12.9% from the regional sporting events and 20.3% from the community events. Of the 15.8% with a diagnosis of asthma or use of asthma medications, 2702 subjects completed all five ACT questions and performed a spirogram that met American Thoracic Society criteria.

Table 1 presents the demographics of the study subjects reported on the basis of their control status based on both FEV^sub 1^ and ACT. There were significant differences observed in age, ethnicity and current smoking status as a function of the control status. Subjects with NWC asthma were older (p < 0.001) and more likely to be current smokers (p = 0.001) than subjects with asthma that was considered controlled. Figure 1 demonstrates that abnormal spirometry is more common with increasing age; however, age was not an important variable in predicting asthma control based on ACT.

Figure 1. Correlation of asthma control status and age. Note: there was no difference in age between the two FEV^sub 1^ ≥ 80% groups (columns 1 and 3) or between the two FEV^sub 1^ < 80% groups (columns 2 and 4). All other comparisons of mean age were statistically different (p < 0.001)

Twenty-seven per cent of the population surveyed met the criteria for NWC asthma based on an ACT score ≤ 19 while 26% had an FEV^sub 1^ measurement below 80% predicted. However, 43% of the total surveyed population had either or both an ACT score ≤ 19 and a FEV^sub 1^ < 80% predicted. NWC asthma was reported in 41% of Caucasians and 48% of African-Americans. Table 1 reports the observed differences in NWC asthma by race. Attendees at the community events were more likely to have one or both of the measures of NWC asthma than subjects attending the regional sporting events, 50% compared with 38%. In addition, approximately 15-16% of subjects with either of these measures of NWC asthma, did not meet the other criteria, while 10% of subjects had both the FEV^sub 1^ < 80% and ACT ≤ 19. Figure 2 demonstrates the percentage of patients who met the NWC asthma criteria with either or both the ACT or FEV^sub 1^ criteria. Although all of these patients self- reported a physician diagnosis of asthma or history of asthma medications use, only 44% of the controlled and 55% of the NWC asthmatics had ever reported a previous spirometry.

Figure 3 displays the overall perception of health status of the subjects. Those with controlled asthma were more likely to perceive excellent or good overall health, 86% versus 67% for the controlled and NWC asthmatics, respectively (p < 0.001). In addition, asthma medication use in the past 3 months was reported more frequently in the NWC compared to the controlled subjects 69% and 39%, respectively. This result corresponded to the ACT question on albuterol utilization, demonstrating that 66% of the NWC patients reported using albuterol in the past month while only 26% of the controlled cohort did.

All five ACT parameters were consistent in their pattern that differentiated control status. Limitations at work, shortness of breath, night-time awakening, albuterol use and overall control were negative responses or completely controlled in 84%, 59%, 87%, 72%, and 61 % of the controlled patients and compared to only 16%, 3%, 22%, 14%, and 3% of the patients who scored < 19 on ACT. The composite of all five questions increases the identification of NWC asthma. Although only 3% of the patients scoring ≤ 19 on ACT reported that their asthma was completely controlled, 31% reported that their disease was well controlled despite the positive report of other disease specific symptoms or limitations.

Discussion

In this large community-based disease screening initiative, 43% of subjects with self-reported asthma demonstrated NWC asthma based on either an abnormal ACT, FEV^sub 1^, or both. Patients with NWC asthma tended to be older and FEV^sub 1^ < 80% was more frequently correlated with increasing age. In addition, the prevalence of NWC asthma was higher in African-Americans compared with Caucasians. In addition, current smoking was associated with more NWC disease.

Figure 2. Percentage of subjects with evidence of NWC asthma based on ACT and/or FEV^sub 1^

Figure 3. Global health as a function of asthma control. p < 0.001 for controlled vs. uncontrolled

Twenty-seven and twenty-six per cent of subjects had NWC asthma determined by ACT and spirometry, respectively. The use of both ACT and spirometry increased the number of patients identified with NWC asthma, increasing the identification to 43% of subjects. The majority of the NWC subjects were identified by only one of the two screening tools, 40% with ACT and 37% with spirometry. These patterns of response are consistent with the pediatric and adult literature that demonstrates the limitation of lung function measurements correlating with respiratory symptoms. Colice and coworkers13 noted that a single parameter frequently determined the disease severity category proposed by the 1997 NAEPP report. Teeter and Bleecker12 have demonstrated a poor correlation between asthma symptoms and measures of airway obstruction including FEV^sub 1^. Further, as asthma symptoms occur and resolve, measures of airway function and symptom recognition do not always change at the same rate18.

These reports support the findings of the present study that suggests the importance of utilizing several different measures of asthma control. Clinical trial data demonstrate that the treatment regimen that produces the greatest mean improvement in FEV^sub 1^ is associated with the greatest mean improvement in symptom scores but there is significant within patient variability19,20. For the individual patient with asthma there may be a poor correlation between FEV^sub 1^ and symptoms reported in an assessment of asthma control. This supports the conclusion of both this paper and the work of Shingo and colleagues14 that parameters that assess different features should be included in the determination of disease activity or response to therapy.

The value of performing both an asthma control assessment with and without spirometry was assessed in a study with the ACQ. This assessment tool was initially reported with the use of spirometry4. Jumper and colleagues have subsequently proposed that the ACQ could be completed without the use of FEV^sub 1^ measurement21. In their analysis the mean ACQ score was 1.52 (0.82), the mean score from symptoms alone was 1.48 (0.93) and the symptoms plus FEV^sub 1^ score was 1.52 (0.87). The FEV^sub 1^ in the ACQ is assessed as seven categories with three of those seven categories (O, 1, and 2) being > 80% predicted. In our analysis, FEV^sub 1^ is a dichotomous variable, normal or abnormal. This difference in methodological approach may explain why the combination of both ACT and FEV^sub 1^ appear to be important determinants of NWC asthma in the present study.

ACT and spirometry both have strengths and limitations. ACT is inexpensive to perform, does not require significant investment in equipment, nor does it necessitate trained personnel to administer the test. It can be utilized as a screening tool for asthma control both within and outside of the medical environment. ACT requires only that the patients properly report their symptoms and rescue medication use.

Spirometry is also an effective tool to identify asthma control status1,6,21. When administered by trained technicians, spirometry is highly reproducible16. Spirometry identifies many patients who do not perceive airflow limitation caused by their asthma. It is responsive to changes in disease activity. Further, spirometry correlates with other markers of disease activity including exhaled nitric oxide16. Pulmonary function testing is limited by availability, the lack of trained personnel and the fact that it is a single point in time measurement. Use of albuterol prior to an office visit will alter the results of spirometry. Patients with predominantly nocturnal asthma23 may not be identified because spirometry is routinely performed during daytime hours. Finally, it is well described that some asthmatics may have normal lung function despite significant disease morbidity11,12. The finding that only 50% of the subjects with self-reported asthma in this study reported having previous spirometry illustrates how this valuable test is infrequently performed.

This study is limited by its reliance on patient recall for responses to the survey questionnaire. There was no determination of the level of disease severity. Furthermore, there was no attempt to assess whether subjects were having acute symptoms. However, this study records the frequency of NWC asthma in diverse community settings.

It is important to point out that although the correlation of FEV^sub 1^ and ACT is incomplete; the association of other biologic markers and clinical parameters is also limited. Green and colleagues24 demonstrated that asthma care that followed a strategy utilizing sputum eosinophils produced a decrease in exacerbations but there was no difference in symptom scores, total asthma quality of lifescores, measures of lung function or the use of rescue albuterol. Similarly, Sont and coworkers25 were unable to demonstrate consistent findings between bronchial hyperreactivity and a number of inflammatory markers found in airway biopsy. These reports do not invalidate any of these measures but rather confirm that there is not a single predictive marker of asthma control. These data and the present study suggest that multiple measures will improve the determination of asthma control.

The use of ACT and spirometry identified that 43% of subjects with asthma had the disease that was NWC. When performed together these two instruments may increase the recognition of individuals with NWC asthma. When spirometry is not available, ACT by itself is a good screening tool to assess asthma control.

Acknowledgment

This study was funded by GlaxoSmithKline. The authors would like to thank Amy Emmett for assisting with the statistical analysis.

* This study was presented as an abstract at the American Academy of Allergy and Clinical Immunology annual meeting, San Antonio, TX, USA, March, 2005

References

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2. Cockcroft DW, Swystun VA. Asthma control versus asthma severity. J Allergy Clin Immunol 1996;98:1016-8

3. Nathan R, Sorkness C, Kosinski M, et al. Development of the Asthma Control Test: a survey for assessing asthma control. J Allergy Clin Immunol 2004;113:59-65

4. Juniper EF, O'Byrne PM, Guyatt GH, et al. Development and validation of a questionnaire to measure asthma control. Eur Respir J. 1999;14:902-7

5. Vollmer W, Markson L, O'Connor E, et al. Association of asthma control with health care utilization and quality of life. Am J Respir Crit Care Med 1999; 160:1647-52

6. National Institutes of Health and National Heart, Lung and Blood Institute. Global strategy for asthma management and prevention [revised 2002]. Available at www.ginasthma.com [accessed 19 April 2005]

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8. Wolfenden LL, Diette GB, Krishman JA, et al. Lower physician estimate of underlying asthma severity leads to undertreatment. Arch Intern Med 2003;163:231-6

9. Halterman JS, Yoos L, Kaczororoski JM, et al. Providers underestimate symptom severity among urban children with asthma. Arch Pediatr Adolesc Med 2002; 156:141-6

10. Spahn JD, Cherniacj R, Paull K, et al. Is forced expiratory volume in one second the best measure of severity in childhood asthma? Am J Respir Crit Care Med 2004; 169:784-6

11. Bacharier LB, Strunk RC, Mauger D, et al. Classifying asthma severity in children: mismatch between symptoms, medication use, and lung function. Am J Respir Crit Care Med 2004; 170: 426-32

12. Teeter JG, Bleecker ER. Relationship between airway obstruction and respiratory symptoms in adult asthmatics. Chest 1998;113:272-77

13. Colice GL, Burrgt JV, Song J, et al. Categorizing asthma severity. Am J Respir Crit Care Med 1999; 160:1962-7

14. Shingo S, Zhang J, Reiss TF. Correlation of airway obstruction and patient-reported endpoints in clinical studies. Eur Resp J 2001;17:220-4

15. Marcus P, Shatz M, Kosinski M, et al. Effectiveness of ACT(TM) and Rules of Two(TM) in screening and monitoring for asthma control. Proc Am Thor Society 2005;2:a255

16. American Thoracic Society. Standardization of spirometry, 1994 update. Am J Respir Crit Care Med 1995;152:1107-13

17. Knudson RJ, Lebowitz DM, Holdberg CJ, et al. Changes in the normal expiratory flow-volume curve with growth and aging. Am Rev Respir Dis 1983;127:725-34

18. Bates CA, Silkoff PE. Exhaled nitric oxide in asthma: from bench to bedside. J Allergy Clin Immunol 2003;111:256-62

19. Zhang J, Yu C, Holgate ST, Reiss TF. Variability and lack of predictive ability of asthma endpoints in clinical trials. Eur Respir J 2002;20:1102-9

20. Bateman ED, Boushey HA, Bousquet J, et al. Can guidelinedefined asthma control be achieved? Am J Respir Crit Care Med 2004; 170:836-44

21. Juniper EF, Svensson K, Mork AC, et al. Measurement properties and interpretation of three shortened versions of the asthma control questionnaire. Resp Med 2005;99:553-8

22. Jones SL, Kittleson J, Cowan JO, et al. The predictive value of exhaled nitric oxide measurements in assessing changes in asthma control Am J Respir Crit Care Med 2001;164:738-43

23. Silkoff PE, Martin RJ. Pathophysiology of nocturnal asthma. Ann Allergy Asthma Immunol 1998;81:378-83

24. Green RH, Brightling CE, McKenna S, et al. Asthma exacerbations and sputum eosinophil counts: a randomized controlled trial. Lancet 2002;360:1715-21

25. Sont JK, Willems LNA, Bel EH, et al. Clinical control and histopathologic outcomes of asthma when using airway hyperresponsiveness as an additional guide to long-term treatment. Am Rev Respir Dis 1999; 159:1043-51

CrossRef links are available in the online published version of this paper: http://www.cmrojournal.com

Paper CMRO-3184_3, Accepted for publication: 14 October 2005

Published Online: 10 November 2005

doi: 10.1185/030079905X74925

Michael LeNoir(a), Alyssa Williamson(b), Richard H. Stanford(c) and David A. Stempel(d)

a Associate Clinical Professor, Pediatrics - University of California, San Francisco, Oakland, CA, USA

b US Wellness Inc., Gaithersburg, MD, USA

c GlaxoSmithKline, Research Triangle Park, NC, USA

d Infomed Northwest, Bellevue, WA and Associate Clinical Professor, Pediatrics, University of Washington, Seattle, WA, USA

Address for correspondence: David A. Stempel, MD, Infomed Northwest, Bellevue, WA, USA. email: econmed@msn.com

Appendix

Copyright Librapharm Jan 2006

Source: Current Medical Research and Opinion

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