Attaining Asthma Control
Attaining Asthma Control
Purpose of Review: Despite our knowledge of asthma pathophysiology and several guidelines, studies have indicated growing morbidity. This review highlights the rationale for the trend in asthma care of separating asthma control from asthma severity.
Recent Findings: Recent research has highlighted why asthma morbidity continues to be such a conundrum. This includes the variability of asthma control over time, inability to achieve total asthma control in some patients, disagreement between various measures of asthma control and the lack of an agreed tool for determining asthma control.
Summary: By dissociating asthma control and severity, the clinician may focus on the level of control during each encounter, independent of asthma medication. One can still build upon the step-up and step-down algorithm, while reinforcing control of asthma as the ultimate goal. Asthma control connotes the status of the disease, highlighting the dynamic nature of this illness both as the response to a trigger as well as therapy. Although more aggressive intervention may be required to achieve adequate control in severe persistent asthma versus mild persistent disease, the goal of appropriate asthma control remains constant in the spectrum of asthma severity.
Despite vast growth in our knowledge regarding the pathophysiology of asthma, and a second instalment of the NHLBI guidelines as well as international guidelines, recent studies have demonstrated a lack of control of asthmatic patients both in the USA and in Europe. These guidelines stress the importance of gaining control in asthma, highlighting the fact that there should be minimal need for β2-agonist use, a minimum of nocturnal awakenings and ideally no exacerbations requiring emergency-room or hospital admission. Unfortunately, Fuhlbrigge and colleagues demonstrated, via a random telephone survey of US households, that these goals of asthma control were not met in the majority of patients. Similar results have been demonstrated by Rabe and colleagues in Europe. Not surprisingly, although there was a reduction in asthma-related hospitalizations in the USA in 1995-1999 compared to previously, there was a rise in emergency-department and out-patient visits during this period. It should be noted that these guidelines were a major step forward in the care of asthmatics as they introduced the concept of classification of asthma by asthma severity (mild, moderate, severe), and linked asthma severity to a step-wise guide in the pharmacotherapy of asthma. The 1991 NHLBI asthma guidelines base the classification of asthma severity on assessment before treatment. This was not difficult, as the majority of asthmatics were not using anti-inflammatory/controller therapy. Over the past decade however, there has been a tremendous growth in use of controller therapy in the care of asthmatics. Thus, classification of asthma severity while the patient is on therapy is problematic. Subsequent revisions of these guidelines introduced the idea of 'medication requirement' to address this concern.
There are many impediments to a perfect asthma-care diagnostic/severity algorithm. Recent guideline schemes have emphasized classifying asthma severity, intimating this to be a static issue. However, recent research has shown asthma severity to be a very dynamic process. This is well demonstrated in the study by Calhoun et al., who found that asthma severity could not be determined in many patients using discrete, point-in-time assessments of lung function or symptom control. By compiling data from two placebo-controlled trials, they examined a group of 85 moderate-to-severe persistent asthmatics who were randomized to receive no controller therapy for 12 weeks. They found asthma severity to vary significantly over time. The mean percentage of treatment weeks that patients would have been classified as mild intermittent were 9%, mild persistent were 14%, moderate persistent were 71% and severe persistent were 6% during the study period. Likewise, in a retrospective analysis of asthma-related death in patients of 20 years of age or younger living in the state of Victoria, Australia, via an interviewer-administered questionnaire, Robertson and colleagues demonstrated that of the 51 deaths, 33% were felt to have had a history of trivial or mild asthma. The authors point out that the majority of deaths were in patients not classified as 'high-risk' asthmatics. Both studies underscore the potential lability in asthma control.
Another potential impediment in defining asthma severity is the fact that asthma symptoms do not always correlate well with classification of asthma severity. This issue appears most significant in a subgroup of asthmatics who are poor perceivers of dyspnea. In this group, clinicians should be wary of a lack of subjective complaints and should rely upon objective measures of lung function (see below).
Lastly, Bateman and colleagues have demonstrated that total asthma control may not be achievable in all asthmatic patients. In their 1-year, randomized, stratified, double-blind, parallel-group study of 3421 patients with uncontrolled asthma (with baseline asthma controller therapy ranging from nothing to up to 1000 µg of inhaled corticosteroid per day) they compared fluticasone to combination salmeterol and fluticasone's ability to achieve one of two rigorous, composite, guideline-based measures of asthma control. The first was defined as 'totally controlled' asthma, in which subjects had no daytime or nighttime symptoms, no need for rescue β2-agonist, no emergency-room visits, no exacerbations (defined as no emergency-room visit or use of oral corticosteroid) and peak flows of ≥ 80% predicted every day for the previous week. The second measure of control was defined as 'well-controlled asthma'. In this case each week a subject was allowed to have up to 2 days of mild daytime symptoms, require up to 2 days of β2-agonist rescue (as long as it was four or fewer occasions per week), with similar morning peak flow, nocturnal awakening and emergency-room/exacerbation criteria as the totally controlled criteria. In the group who were in poor control at randomization (baseline) despite high-dose inhaled corticosteroid therapy, even with intervention, using high-dose salmeterol/fluticasone therapy, the majority were not able to achieve total asthma control.
Purpose of Review: Despite our knowledge of asthma pathophysiology and several guidelines, studies have indicated growing morbidity. This review highlights the rationale for the trend in asthma care of separating asthma control from asthma severity.
Recent Findings: Recent research has highlighted why asthma morbidity continues to be such a conundrum. This includes the variability of asthma control over time, inability to achieve total asthma control in some patients, disagreement between various measures of asthma control and the lack of an agreed tool for determining asthma control.
Summary: By dissociating asthma control and severity, the clinician may focus on the level of control during each encounter, independent of asthma medication. One can still build upon the step-up and step-down algorithm, while reinforcing control of asthma as the ultimate goal. Asthma control connotes the status of the disease, highlighting the dynamic nature of this illness both as the response to a trigger as well as therapy. Although more aggressive intervention may be required to achieve adequate control in severe persistent asthma versus mild persistent disease, the goal of appropriate asthma control remains constant in the spectrum of asthma severity.
Despite vast growth in our knowledge regarding the pathophysiology of asthma, and a second instalment of the NHLBI guidelines as well as international guidelines, recent studies have demonstrated a lack of control of asthmatic patients both in the USA and in Europe. These guidelines stress the importance of gaining control in asthma, highlighting the fact that there should be minimal need for β2-agonist use, a minimum of nocturnal awakenings and ideally no exacerbations requiring emergency-room or hospital admission. Unfortunately, Fuhlbrigge and colleagues demonstrated, via a random telephone survey of US households, that these goals of asthma control were not met in the majority of patients. Similar results have been demonstrated by Rabe and colleagues in Europe. Not surprisingly, although there was a reduction in asthma-related hospitalizations in the USA in 1995-1999 compared to previously, there was a rise in emergency-department and out-patient visits during this period. It should be noted that these guidelines were a major step forward in the care of asthmatics as they introduced the concept of classification of asthma by asthma severity (mild, moderate, severe), and linked asthma severity to a step-wise guide in the pharmacotherapy of asthma. The 1991 NHLBI asthma guidelines base the classification of asthma severity on assessment before treatment. This was not difficult, as the majority of asthmatics were not using anti-inflammatory/controller therapy. Over the past decade however, there has been a tremendous growth in use of controller therapy in the care of asthmatics. Thus, classification of asthma severity while the patient is on therapy is problematic. Subsequent revisions of these guidelines introduced the idea of 'medication requirement' to address this concern.
There are many impediments to a perfect asthma-care diagnostic/severity algorithm. Recent guideline schemes have emphasized classifying asthma severity, intimating this to be a static issue. However, recent research has shown asthma severity to be a very dynamic process. This is well demonstrated in the study by Calhoun et al., who found that asthma severity could not be determined in many patients using discrete, point-in-time assessments of lung function or symptom control. By compiling data from two placebo-controlled trials, they examined a group of 85 moderate-to-severe persistent asthmatics who were randomized to receive no controller therapy for 12 weeks. They found asthma severity to vary significantly over time. The mean percentage of treatment weeks that patients would have been classified as mild intermittent were 9%, mild persistent were 14%, moderate persistent were 71% and severe persistent were 6% during the study period. Likewise, in a retrospective analysis of asthma-related death in patients of 20 years of age or younger living in the state of Victoria, Australia, via an interviewer-administered questionnaire, Robertson and colleagues demonstrated that of the 51 deaths, 33% were felt to have had a history of trivial or mild asthma. The authors point out that the majority of deaths were in patients not classified as 'high-risk' asthmatics. Both studies underscore the potential lability in asthma control.
Another potential impediment in defining asthma severity is the fact that asthma symptoms do not always correlate well with classification of asthma severity. This issue appears most significant in a subgroup of asthmatics who are poor perceivers of dyspnea. In this group, clinicians should be wary of a lack of subjective complaints and should rely upon objective measures of lung function (see below).
Lastly, Bateman and colleagues have demonstrated that total asthma control may not be achievable in all asthmatic patients. In their 1-year, randomized, stratified, double-blind, parallel-group study of 3421 patients with uncontrolled asthma (with baseline asthma controller therapy ranging from nothing to up to 1000 µg of inhaled corticosteroid per day) they compared fluticasone to combination salmeterol and fluticasone's ability to achieve one of two rigorous, composite, guideline-based measures of asthma control. The first was defined as 'totally controlled' asthma, in which subjects had no daytime or nighttime symptoms, no need for rescue β2-agonist, no emergency-room visits, no exacerbations (defined as no emergency-room visit or use of oral corticosteroid) and peak flows of ≥ 80% predicted every day for the previous week. The second measure of control was defined as 'well-controlled asthma'. In this case each week a subject was allowed to have up to 2 days of mild daytime symptoms, require up to 2 days of β2-agonist rescue (as long as it was four or fewer occasions per week), with similar morning peak flow, nocturnal awakening and emergency-room/exacerbation criteria as the totally controlled criteria. In the group who were in poor control at randomization (baseline) despite high-dose inhaled corticosteroid therapy, even with intervention, using high-dose salmeterol/fluticasone therapy, the majority were not able to achieve total asthma control.
