To Determine the Measurement Properties of the ACT in an African American Adolescent Population With Persistent Asthma Followed at a Subspecialty Clinic
To Determine the Measurement Properties of the ACT in an African American Adolescent Population With Persistent Asthma Followed at a Subspecialty Clinic
Purpose: To determine the measurement properties of the asthma control test (ACT) in a prospective clinical study in an African American adolescent population.
African Americans have a higher rate of asthma (11.2%) compared to whites (7.7%), according to the Centers for Disease Control and Prevention, and this asthma is disproportionally not well-controlled. African Americans have higher mortality from and healthcare utilization for their asthma. Their asthma severity is more likely to be underestimated by their "main asthma provider". African-American adolescents are at particularly high risk of asthma-related morbidity and mortality.
Because asthma control is now the focus of asthma care, assessment of control is the critical step in appropriate management. The two domains of asthma control, impairment and risk, evaluate the role asthma plays in a patient's quality of life and functional capacity on an ongoing basis and the risk their asthma presents for future adverse events. Although NAEPP guidelines contain a rubric for asthma control based on these domains, thus representing the "gold standard" for asthma care, their utilization may be time-consuming and cumbersome to implement in primary care offices, and primary care providers may be unfamiliar with their use. Minorities see subspecialists less often than Caucasians (28.3% vs 41%, p=0.001), and this difference could not be explained by age, gender, health insurance, education, employment, patient preference, or frequency of respiratory symptoms. For primary care practices following these patients, it remains imperative that the tools being used to gauge asthma control be evaluated and validated in this at-risk population.
At this time, there are approximately 17 questionnaires available for use in the assessment of asthma control, although most are not well validated. Of these, the most widely validated and most commonly used instrument is the Asthma Control Test (ACT). The ACT is a self-administered questionnaire intended to assess the impairment domain over the past four weeks and is completed by patients starting at age 12. The ACT has five questions with an overall best score of 25. For primarily adult Caucasian populations, the ACT has been found to be a valid, reliable, and responsive instrument of asthma control, and cut-offs for controlled and not well-controlled asthma (< 19) as well as minimal clinically important (MIC) differences (3 points) have been identified. However, measurement properties of the ACT are lacking in the African American adolescent asthma population. The landmark validation study for the ACT by Schatz et al was comprised of a large sample size of over 300 patients that showed that a cut-off score of 19 as distinguishing well-controlled versus not well-controlled asthmatics. However, the mean age was 35 for that study population, and concerns have been raised as to whether this cut-off is appropriate for adolescents in general. Moreover, concerns have been raised as to the application of these cut-offs for different ethnic populations. Recent studies examining the ACT in pediatric adolescent populations have found higher optimal cut points to distinguish control classifications; these groups included both European cohorts as well as children of Mexican descent in Southern California. The ACT has not been validated in a more ethnically diverse population such as in African American adolescents.
The measurement properties of validity, reliability, and responsiveness are critical to the usefulness of any questionnaire in both clinical and research settings. To date, we have been unable to identify a study that evaluated the measurement properties of the ACT in this at-risk minority population.
Lung function measures are included in the rubric of assessing asthma control by the NAEPP. Per these recommendations, spirometry should be available to physicians caring for asthma patients and used with initiation of treatment, change in asthma control, and every one to two years. While subspecialists often have access to spirometry, office-based spirometry is time-consuming, requires technical ability and staff training, equipment maintenance and calibration, and is not always available or feasible for use in primary care physician offices. Because spirometry may be of limited accessibility to primary care providers, questionnaires are quickly taking a leading role in asthma management. However, African Americans perceive asthma symptoms differently than Caucasians. They report less nighttime awakening and dyspnea, two symptoms that account for 20% of the ACT score, and children are less accurate describing their perceived asthma control. This type of under-reporting reflects a false level of asthma control when queried by the ACT and leads to inappropriate medical management when spirometry is not utilized.
Additionally, health literacy is often underestimated. In a review by Diette of approximately 500 mostly African American patients who were asked to read asthma information, only 27% were able to read at a high school level, the level at which most health information and instructions are written. Patients with limited health literacy and chronic illness know less about how to manage their disease and have a higher likelihood of poorly controlled disease and health status compared to their counterparts with higher health literacy. Due to this, the IOM identifies health literacy as being fundamental to quality care and also considers it a priority in health-care quality and disease prevention. Because currently used questionnaires are often provided to patients at the time of intake at a clinic visit for self-administration, a high level of health literacy in this minority adolescent population is a dangerous assumption that must be considered when addressing the utilization of tools in the assessment of asthma control by primary care providers and subspecialists alike.
As exploratory endpoints, we will obtain fractional exhaled nitric oxide (FeNO) measurements shortly after spirometry is performed. Elevated FeNO indicates eosinophilic airway inflammation and assists in assigning the correct asthma phenotype, which can have implications for asthma management. We will also obtain nasal epithelial lining fluid (ELF) for collection of nasal cytokines and chemokines. This information is useful for expanding our current understanding of the inflammatory mediators involved in asthma-associated airway inflammation.
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