Assessment of Asthma Control Using Asthma Control Test ( ACT ) and it Relationship with Lung Function Parameters

Background: Bronchial Asthma is a disease with increasing global significance. Its prevalence is projected to increase to 400 million by the year 2025 as compared to the present estimate of 300 million. Previously asthma was assessed mainly in terms of symptoms and measures of lung functions but more recently these indices have not been able to reflect the true state of the asthmatics. The focus is now shifting to an assessment and treatment approach based on control. Asthma Control Test (ACT) is a validated, simple and inexpensive instrument to assess control among patients with bronchial asthma. However, its relationship with lung function parameters is yet to be demonstrated among Nigerian asthmatic patients. Aim: The study aimed at assessing asthma control using ACT scores and to determine its relationship with lung function parameters among persons with asthma in a university respiratory clinic. Methodology: It was a cross-sectional study. The study included 65 patients with bronchial asthma who underwent routine check-ups in respiratory clinics at the Obafemi Awolowo University Teaching Hospital Complex (OAUTHC) Ile-Ife, Nigeria between October 2009 and January 2011. The ACT was administered to assess for asthma control. Lung function test was done using the guidelines of American Thoracic Society (ATS). Results: The mean pre-bronchodilator FEV1 was 1.97 ± 0.87L, mean ACT score was 18.2+4.28, 24 (37%) of the study subjects had well-controlled asthma. The ACT scores were weakly correlated with percentage of predicted Forced Expiratory Volume in 1 second, FEV1(r=0.220, p=<0.078) and Peak Expiratory Flow, PEF(r=0.168, p= 0.18). Conclusion: In this study, most of the patients had poor asthma control and lung function parameters correlated poorly with Asthma Control Test (ACT) scores. It is important that the ACT complements other physiological measures of assessing asthma control in our environment.


INTRODUCTION
Bronchial Asthma is a worldwide disease which affects all ages, sexes and racial groups.It affects 300 million people globally with an expected increase of prevalence to 400 million by the year 2025 (John Rees, 2006).It poses a substantial and unacceptable health and economic burden (Smith et al., 1997).
International guidelines indicate that the primary goal of asthma management is to obtain control and reduce the risk of exacerbations (Woolcock et al., 1989).
Asthma control refers to the control of disease manifestations both in terms of symptoms and laboratory investigations (International Consensus Report on Diagnosis and Treatment of Asthma, 1992).
Poor assessment of asthma control is a major cause of suboptimal asthma management worldwide so the focus is now shifting to an assessment and treatment approach based on control.
While there is no comprehensive tool to identify and define asthma control, several instruments have been developed, tested and validated over the last several years for their reliability and reproducibility to measure control (Vollmer et al.,2002;Juniper et al., 1999;Boulet et al.,2002;Nathan et al. 2004).
The ACT was developed by Nathan and colleagues in 2004 and is a trademark of Quality Metric (Lincoln RI).It is a validated, reproducible and reliable tool in assessing asthma control.
Studies conducted in Canada (Joyce et al., 1999;FitzGerald et al., 2006), Europe (Rabe et al., 2000), Asian-Pacific area (Lai et al. Asthma. 2003) and South Africa (Greeblatt et al.,2010) suggest that a substantial cases of asthma are not well controlled.A study carried out by Adeyeye et al., 2008 in Lagos, Nigeria has also corroborated findings in other parts of the world that asthma is not well controlled.
Spirometry as a measure of lung function provides complementary information that is not provided by other outcome variables However, is unclear how spirometry relates with ACT as a complimentary measure in the assessment of persons with asthma.
There is paucity of research work assessing control using ACT and its relationship with lung function parameters among asthmatics in Nigeria.The present study was aimed at assessing asthma control using a validated ACT among Nigerian asthmatics and to assess how it relates and complements lung function parameters.

METHODOLOGY
This study was carried out in the Medical clinics/wards of Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC).
It was a cross sectional analytical study.Persons with asthma were recruited consecutively into the study.A total of 65 patients age between 16-55 years who had spirometric evidence of asthma as defined by a bronchodilator reversibility test with change in FEV 1 >15% and/or 200ml, 20 minutes after inhalation of 400 microgram of β-agonist (salbutamol) were included .In addition, only those without an acute exacerbations of asthma in the prior 4 weeks were included in the sample.
All asthmatics that had co-morbid conditions like hypertensive heart failure and COPD, patients with acute severe asthma and unconfirmed diagnosis of asthma were excluded.
A pro-forma, Medical Research Council (MRC) questionnaire was used to record information on sociodemographic data and symptom profile from each patient and data obtained were summarized.
Asthma control was assessed by self-reported Asthma Control Questionnaires, Asthma Control Test (ACT).The ACT is a 5-item questionnaire that assesses interference with activity, shortness of breath, nocturnal symptoms, rescue medication use and self-rating of asthma control.Each item is scored using 1-5 scale and then summed (total score 5-25).A score of 20 or higher was found to be the most discriminating cut off to define well controlled asthma and a score lower than 15 was identified as the most discriminating cut-off to define asthma that was poorly controlled.ACT scores of 15-19 denotes not well-controlled asthma Lung function tests were performed according to the American Thoracic Society guidelines (American Thoracic Society.Standardization of Spirometry, 1994 update).
Data obtained were analyzed with Statistical Package for Social Sciences (SPSS) version 16.0.Continuous variables were expressed as means ± standard deviation and categorical variables as percentages.
The chi-square test was used to determine the statistical significance of association between categorical variables while student t-test was used for the continuous variables.Correlation between levels of asthma control by ACT scores and lung function parameters were assessed using Pearson's linear correlation co-efficient, P-value of <0.05 was considered significant.

RESULTS
Socio-demographic characteristics of the patients who participated in the study are shown below in Table1.Females constituted 38(58.5%) of the study subjects while 27 (41.5%)were males.Only 17 (26%) of the subjects were on controller medications for asthma.Twenty five (38.5%) of the respondents have had the diagnosis of asthma for 15 years and above.The mean pre-bronchodilator FEV 1 was 1.97 ± 0.87, while the post bronchodilator FEV 1 was 2.32 ± 0.95.The predicted pre-bronchodilator FEV 1 was 75 ± 25.7.As shown, the subjects fulfilled the entry criteria of reversibility of 15% in the FEV 1 and PEF. Figure 1 below shows the distribution of the study subjects according to the level of control based on the ACT questionnaire scores.As shown, 24 (37%) of subjects had well controlled asthma while 28 (43%) and 13 (20%) had not well controlled and poorly controlled asthma respectively.Table 3 shows the clinical and demographic characteristics of the subjects grouped based on their ACT scores.Ten (42%) of the well-controlled group used controller medications compared to 5 (12%) of the not well-controlled that did not use controller medications.The difference was statistically significant P<0.029.

DISCUSSION
This study assessed the level of asthma control using the Asthma Control Test (ACT) among patients with bronchial asthma in a developing country.The study also sought to determine the relation between ACT and lung function parameters in clinical evaluation of persons with asthma.
Several studies have been carried out around the world to assess asthma control using various instruments (Juniper et al., 2006;Skinner EA, et al. 2004;Peters D, et al.,2006;LeBlanc A et al., 2007;Mendoza et al.,2007).The ACT has been validated against specialist's rating of asthma control, spirometry and quality of life (Schatz M., et al., 2007).
The overall mean score as measured by ACT was 18.20±4.28,with only 37% of the subjects scoring 20 and above which denotes well-controlled asthma.These findings showed that asthma was poorly controlled among the respondents.This study corroborated the findings of Adeyele et al, 2008 working in LUTH who demonstrated that asthma control was poor among the study subjects.
Findings similar to this index study were reported by Mendoza et al  ., 2007 using the ACT in a hospital-based study in The Philippines.They found that only 28% of the respondents had well controlled asthma.
The Reality of Asthma Control (TRAC) (FitzGerald et al., 2006) study using the Canadian Asthma Consensus guidelines showed that only 47% of respondents had controlled asthma.
Similar observations were made in the Asthma Insight and Reality in Europe (AIRE) (Rabe et al., 2000) and International Asthma Patient Insight Research (INSPIRE) study (Partridge et al., 2006).
In this study, bronchial asthma was found to be commoner among the females, 38 (58.5%) of the respondents were found to be females.
The lung function values for the respondents showed a mean pre-bronchodilator FEV 1 of 2.29L ± 1.08 and 1.75L ± 0.59 for males and females respectively.
Females appear to have lower overall ACT scores compared to males.This is consistent with the findings of Tovt-Korshynka et al., 2000 that in asthma, as in several chronic disease settings, females may report symptoms differently from males, being more likely to seek medical care.
However, physiological explanations are also of potential importance.Nonspecific bronchial hyperresponsiveness has been reported to be more common among females than males in general population surveys (Manfreda et al. 2004).However, this phenomenon needs to be further evaluated in other socio-cultural setting and stimulate further work in ACT in diverse communities.
This study showed that only 26% of the respondents were using controller medications.This figure is lower compared to the work of Marks et al., 2007 who found out that 35.6% of adult asthmatics with daily symptoms and 41.4% with symptoms on most days were taking controller medications.
There was a significant correlation between ACT scores and use of controller medications.Subjects on controller medications appear to have a better ACT scores than respondents that are not on controller medications.This finding corroborated a work done by Green RJ et al., 2010 in South Africa who found out that asthmatic on controller medications achieved better control.
Also evaluated in this study was the relationship between ACT scores and lung function parameters.There was a poor correlation between ACT scores and lung function variables.
The poor correlation may be partly due to the lack of specificity of asthma symptoms and to differences in the magnitude and time course of the response to treatment (Reddel et al., 2000).
Symptoms and lung function parameters represent different domains of asthma and they correlate poorly over time in individual patients, so both need to be monitored by clinicians assessing asthma control in clinical practice ( Dorinsky et al., 2001;Sharek et al., 2002).
However, a study done by Mendoza et al., 2007 showed a significant correlation between FEV 1 and ACT scores.This significant correlation probably was a result of the fact that the sample size was higher and it was a cohort prospective study which followed up the subjects over time as contrasted to the index study which took crosssectional look at lung Function variables and ACT scores. .

CONCLUSION
In conclusion, the present study showed that asthma is poorly controlled among the study subjects.It also showed that lung function parameters correlate poorly with Asthma Control Test (ACT) scores.These findings highlight the importance of control-based approach to management and the importance of a multi-dimensional strategy in the evaluation of persons with asthma.

Limitations
This study is limited because it is a hospital-based study so may not be generally representative of all the asthmatics in the general population.A community-based study would have added value to the findings.There is therefore need for a large multicenter study to assess asthma control using ACT in our environment.

Figure 1 :
Figure 1: Distribution of the study subjects according to the levels of Asthma Control.

Table 3 : Characteristics of subjects grouped based on their ACT scores. Clinical and demographic characteristics ACT well-controlled (≥20) ACT not-well controlled (≤20) P-value
The relationship between the levels of Asthma Control (ACT) and the lung function parameters of the subjects is shown below in table 4.There was no significant relationship between lung function variables and ACT scores.