Is overall asthma control being achieved? A hypothesis-generating study

Asthma economics: focusing on therapies that improve costly outcomes

PURPOSE OF REVIEW

In 1998, the economic burden of asthma was estimated to be 12.7 billion dollars. Subsequent research has focused on identifying important outcomes that reflect high resource utilization and finding therapies that improve these outcomes and decrease cost. Recent developments include an update to the National Heart, Lung, and Blood Institute (NHLBI) guidelines, new treatment strategies using combination therapy, and the development of a monoclonal antibody therapy for asthma.

RECENT FINDINGS

Two important costly outcomes are asthma-related hospitalizations and emergency department visits. Asthma-related hospitalizations started to decline in the 1990s, primarily in white Americans, but not in young African Americans. Many hospitalizations and emergency department visits are preventable, and costs were lowered by shifting management to the ambulatory care setting. Increased asthma severity and suboptimal compliance with NHLBI asthma care guidelines can contribute to the persistence of symptoms, which triggers behaviors that increase resource utilization.A recent economic analysis was one of the first well-controlled clinical trials to show that inhaled corticosteroids provide clinical benefit at modest costs. Combination therapy, particularly that containing an inhaled corticosteroid and long-acting bronchodilator in a single inhaler, potentially can reduce overall costs by improving compliance with inhaled corticosteroids. Nonpharmacologic therapies also have been shown to be cost-effective. However, a significant number of patients with asthma continue to have symptoms even while on recommended controller therapy. Omalizumab, a monoclonal antibody treatment that binds IgE, was released in the summer of 2003.

SUMMARY

Many costly asthma-related hospitalizations and emergency department visits are preventable, and chronic disease care can be shifted to the ambulatory setting. Increased asthma severity and noncompliance with NHLBI guidelines are associated with increased resource utilization. Combination therapies can assist in improving patient compliance, and omalizumab potentially offers a novel but expensive way to decrease symptoms and resource utilization.

Short-acting beta 2-agonist and oral corticosteroid use in asthma patients prescribed either concurrent beclomethasone and long-acting beta 2-agonist or salmeterol/fluticasone propionate combination

Prescriptions for short-acting beta(2)-agonists (SABAs) and oral corticosteroids recorded in a primary care database were used as markers of asthma control. Drug use in the 6 months before and after step-up in treatment from inhaled corticosteroids [ICs; total daily dosage of < or =1000 microg beclomethasone dipropionate (BDP) or equivalent] to either salmeterol/fluticasone propionate combination (SFC) or concurrent BDP and long-acting beta(2)-agonists (LABAs) given in separate inhalers was compared. After step-up, the calculated median number of doses of SABAs prescribed fell by 100 in the SFC group (n = 211) but was unchanged with BDP + LABA (n = 377, p < 0.0001), and fewer patients in the SFC group were prescribed oral corticosteroids (13.7 vs. 20.7%, p = 0.036). Other measures of SABA use after step-up indicated lower use in the SFC group. In clinical practice, adding LABA to IC therapy by using a combination inhaler produces significantly better asthma control than administering the drugs in separate inhalers.

Combination therapy of long-acting beta2-adrenoceptor agonists and corticosteroids for asthma

Twice-daily combination therapy of inhaled corticosteroids and long-acting beta2-adrenoceptor agonists (LABA) is now established as a most effective treatment for moderate to severe asthma and is available in a combined single inhaler. The benefits of combination therapy include better day-to-day control and a reduction in exacerbations compared with monotherapy with inhaled corticosteroids at a lower dose. Total control of asthma, defined as no daytime or night-time symptoms, no use of rescue beta2-adrenoceptor agonists (beta2-agonists), no exacerbations and a peak flow rate of >80% predicted, may be achieved with the use of combined salmeterol/fluticasone in up to 41% of patients with moderate to severe asthma, compared with only 28% of patients treated with fluticasone alone. Adjustable maintenance dosing with budesonide/formoterol may provide better control when compared with fixed-dosing combination regimens. Other therapies combining effectively with inhaled corticosteroids include slow-release theophylline and leukotriene inhibitors, montelukast and zafirlukast, but LABA are the most efficacious. Molecular interactions between corticosteroids and beta2-adrenoceptors may underlie the clinical added benefits of combination therapy. Corticosteroids may increase the number of beta2-adrenoceptors and their coupling with Gs proteins, while beta2-agonists may induce glucocorticoid receptor nuclear translocation, activate transcription factor/enhancer binding protein C/EBPalpha together with corticosteroids, or phosphorylate corticosteroid receptors. The combination of corticosteroids and LABA potentiates inhibition of interleukin-8 and eotaxin release from human airway smooth muscle cells and granulocyte-macrophage colony-stimulating factor release from epithelial cells, and also the inhibition of airway smooth muscle cell proliferation. It is important to determine whether there is a potentiating effect of combination therapy compared with corticosteroid treatment alone on airway inflammation and airway wall remodelling. Improvements in combination therapy include a once-daily preparation and possible combination of inhaled corticosteroids with newer drugs such as phosphodiesterase IV inhibitors.

Assessment of asthma control and severity

OBJECTIVE

To provide a conceptual framework for defining severity and control in asthma, to describe recent advances in measuring asthma control, and to discuss the role of severity and control in asthma disease management.

DATA SOURCES

MEDLINE was searched for relevant English-language articles published between 1998 and July 2003. Additional sources included key references cited in these articles, national and international guidelines for the diagnosis and management of asthma, and the author's personal bibliography.

STUDY SELECTION

All studies that reported on the development and validation of formal measures of asthma control, as well as the few editorials that focused on the distinction between asthma severity and control, were included. The author's professional judgment was used to select for illustrative purposes from among the many purported measures of asthma severity in the literature.

RESULTS

Although several standardized measures of asthma control exist, no direct comparisons of the performance and properties of these control measures have been published. The available instruments appear more similar than dissimilar. All share the common trait of assessing multiple aspects of asthma control, which is believed to provide better discrimination than a single measure.

CONCLUSIONS

Asthma control is different from asthma severity and may be useful as a clinical vital sign for patients with asthma. Ultimately, no one measure may be better than any of the others or the optimal measure may depend on the intended use of the scale.

Anti-IgE therapy in allergic disease

PURPOSE OF REVIEW

Recombinant monoclonal humanized anti-IgE has put forward a fundamentally new concept for the control of allergic disorders. This review will present recent data from clinical studies with anti-IgE in asthma, allergic rhinitis, and food allergy and will examine the place of anti-IgE among current therapeutic options for the treatment of asthma.

RECENT FINDINGS

Therapy with anti-IgE depresses circulating free IgE to the limits of detection, inhibits early- and late-phase responses to allergens, suppresses inflammation and improves the control of allergic diseases. In moderate to severe asthma it results in fewer exacerbations and a lower requirement for both corticosteroids and beta-agonists. IgE appears to be an important regulator of high-affinity Fc receptors (FcepsilonRI) and, in the mouse, to enhance mast cell survival and activation. IgE receptors have been found on diverse inflammatory cells. Anti-IgE reduces the expression of FcepsilonRI on inflammatory cells. Current work has documented a marked decrease in tissue eosinophils, lymphocytes, and interleukin-4-positive cells by anti-IgE treatment and has provided insight into the mechanisms underlying improved control of asthma.

SUMMARY

Clinical studies with anti-IgE have promoted and will continue to advance the understanding of IgE-mediated disease mechanisms. They have documented its efficacy in the treatment of allergic diseases, but much remains to be learned about the most effective clinical strategies and the selection of patients for therapy.

Evaluation of the Asthma Life Quality test for the screening and severity assessment of asthma

BACKGROUND

Asthma Life Quality (ALQ) test, a 20-question questionnaire developed by the American College of Allergy, Asthma and Immunology, has been shown to be useful for asthma diagnosis. We aimed to determine the relation between ALQ scores and (a) diagnosis of asthma; (b) physician's classification of asthma severity according to National Institutes of Health/Global Initiative for Asthma (GINA).

METHODS

Standard translation and cultural adaptation to Portuguese was performed. Patients self-administered the ALQ in the waiting room; the attending allergist classified them, blindly for the test. The scores of nonasthmatics were compared with those of asthma patients. Asthma patients were analyzed in two severity groups: intermittent and mild persistent asthma (IMPA), and moderate and severe persistent asthma (MSPA); sensitivity, specificity, positive and negative predictive values were calculated and receiver operating characteristic curve plotted. Logistic regression analysis models were computed.

RESULTS

From 283 patients, 237 tests were analyzed. Non-asthmatic patients ALQ scores (mean +/- SD) were 6 +/- 4 and, for asthmatics, 10 +/- 5 [mean difference 4.6 (95%CI 3.3-5.9)]. The odds of positive diagnosis increased 1.27 times (95%CI 1.17-1.38) for each one-unit increase in the test. For asthma severity ALQ scores were 9 +/- 4 for IMPA, 15 +/- 3 for MSPA [difference 6.0 (95%CI 4.8-7.1)]; with a sensitivity of 88% and specificity of 74% for a score of 12. The odds of MSPA increased 1.49 times (95%CI 1.28-1.74) per unit increase in ALQ.

CONCLUSIONS

ALQ can help both to identify patients with asthma and to differentiate those more likely to have moderate/severe asthma. These are relevant characteristics for the possible use of this simple, self-administered questionnaire in the assessment of asthma patients needing additional medical management.

Can Guideline-defined Asthma Control Be Achieved?

For most patients, asthma is not controlled as defined by guidelines; whether this is achievable has not been prospectively studied. A 1-year, randomized, stratified, double-blind, parallel-group study of 3,421 patients with uncontrolled asthma compared fluticasone propionate and salmeterol/fluticasone in achieving two rigorous, composite, guideline-based measures of control: totally and well-controlled asthma. Treatment was stepped-up until total control was achieved (or maximum 500 microg corticosteroid twice a day). Significantly more patients in each stratum (previously corticosteroid-free, low- and moderate-dose corticosteroid users) achieved control with salmeterol/fluticasone than fluticasone. Total control was achieved across all strata: 520 (31%) versus 326 (19%) patients after dose escalation (p < 0.001) and 690 (41%) versus 468 (28%) at 1 year for salmeterol/fluticasone and fluticasone, respectively. Asthma became well controlled in 1,071 (63%) versus 846 (50%) after dose escalation (p < 0.001) and 1,204 (71%) versus 988 (59%) at 1 year. Control was achieved more rapidly and at a lower corticosteroid dose with salmeterol/fluticasone versus fluticasone. Across all strata, 68% and 76% of the patients receiving salmeterol/fluticasone and fluticasone, respectively, were on the highest dose at the end of treatment. Exacerbation rates (0.07-0.27 per patient per year) and improvement in health status were significantly better with salmeterol/fluticasone. This study confirms that the goal of guideline-derived asthma control was achieved in a majority of the patients.

Categorizing asthma severity: an overview of national guidelines

Asthma is an inflammatory disease of the airways associated with intermittent episodes of bronchospasm. Corticosteroids are the most effective anti-inflammatory class of medication currently available for the treatment of asthma. However, as higher doses of inhaled corticosteroids are used the risks of systemic exposure and side effects will correspondingly increase. Justification of the benefits from higher doses of inhaled corticosteroids can only be made if patients with more severe asthma can be identified. Methods to categorize asthma severity have been introduced in various national asthma management guidelines. Unfortunately, there are substantial conceptual and practical differences among these recommended approaches to asthma severity categorization. Furthermore, these recommended approaches suffer from a focus on features of asthma control, such as symptoms, short-acting beta-agonist use, and lung function rather than actual measures of asthma severity that would encompass markers of airway inflammation. Without the endpoints necessary to assess airway inflammation, current recommendations for asthma severity categorization may lead to systematic under dosing of appropriate anti-inflammatory therapy with subsequent perpetuation of the asthma exacerbation cycle.

Managing asthma in the real world

Asthma treatment is suboptimal in many patients, with impacts on morbidity and mortality, healthcare resource utilisation and patients' quality of life. The reasons for this include the inherent variability of asthma and the unpredictability of exacerbations, which can range from mild to fatal. In addition, asthma can be difficult to diagnose, particularly in the very young and old. Although treatment guidelines are widely available and well publicised, surveys have identified a significant gap between treatment aims and current levels of asthma control. Patient adherence to inhaled corticosteroids is poor, and many patients rely on short-acting beta2-agonists. The reasons for this are complex but are believed to include poor perception by patients of their asthma severity, concerns about the safety and efficacy of medication and low treatment expectations. Patients appear to be unaware of the extent to which airway inflammation can be controlled and are therefore satisfied with poor asthma control, accepting a high level of symptoms. Increasing patient understanding of asthma and its treatment, allowing patients greater involvement in treatment decisions, increasing the role of asthma nurses and improved communication between physicians and patients may improve outcomes in patients with asthma.

Effects of inhaled corticosteroids, leukotriene receptor antagonists, or both, plus long-acting beta2-agonists on asthma pathophysiology: a review of the evidence

Chronic inflammation and smooth muscle dysfunction are consistent features of asthma, and are responsible for disease progression and airway remodelling. The development of chronic airway inflammation depends upon the recruitment and activation of inflammatory cells and the subsequent release of inflammatory mediators, including cytokines. Cellular and histological evaluation of drugs with anti-inflammatory activity, such as inhaled corticosteroids (ICSs), is achieved by analysing samples of lung tissue or biological fluids, obtained by techniques such as bronchial biopsy, bronchoalveolar lavage and sputum induction. These provide valuable information on the inflammatory processes occurring in the lung, although not all are equal in value. The beneficial effects of ICSs in asthma treatment are a consequence of their potent and broad anti-inflammatory properties. Furthermore, there have been promising results indicating that ICSs can reverse some of the structural changes that contribute to airway remodelling. Long-acting beta2-agonists (LABAs) added to ICSs provide greater clinical efficacy than ICSs alone, suggesting the possibility of complementary activity on the pathophysiological mechanisms of asthma: inflammation and smooth muscle dysfunction. Leukotrienes play a part in the pathogenesis of asthma. Leukotriene receptor antagonists (LTRAs) directly inhibit bronchoconstriction and may have some anti-inflammatory effects, although the extent to which inhibiting one set of inflammatory mediators attenuates the inflammatory response is questionable. In concert with their effect on a broad variety of inflammatory mediators and cells, treatment with ICSs (including ICSs and LABAs) results in superior control of the pathophysiology of asthma and superior clinical efficacy as assessed by the greater improvements in pulmonary function and overall control of asthma compared with LTRAs.

Adjustable maintenance dosing with budesonide/formoterol compared with fixed-dose salmeterol/fluticasone in moderate to severe asthma

BACKGROUND

Current asthma guidelines recommend that patients are educated to adjust their medication according to their asthma severity using physician-guided self-management plans. However, many patients take a fixed dose of their controller medication and adjust their reliever medication according to asthma symptoms.

OBJECTIVES

This study examined whether asthma control improved if patients adjusted the maintenance dose of budesonide/formoterol (Symbicort Turbuhaler* 160/4.5 microg) according to asthma severity compared with traditional fixed dosing (FD) regimens.

METHODS

Symptomatic patients with asthma (n = 658, mean symptom score 1.5, mean inhaled corticosteroids 735 microg/day, mean forced expiratory volume in 1 second [FEV(1)] 84% predicted) were randomised after 2 weeks' run-in to either: budesonide/formoterol adjustable maintenance dosing (AMD), budesonide/formoterol FD or salmeterol/fluticasone (Seretide Diskus dagger 50/250 microg) FD. In a 4-week double-blind period, both budesonide/formoterol AMD and FD groups received two inhalations twice daily (bid) and salmeterol/fluticasone FD patients received one inhalation bid. In the following 6-month open extension, both FD groups continued with the same treatment. Patients in the AMD group with well-controlled asthma stepped down to one inhalation bid; others continued with two inhalations bid. All AMD patients could increase to four inhalations bid for 7-14 days if symptoms worsened. All patients used terbutaline or salbutamol for symptom relief throughout. The primary variable was the odds of achieving a well-controlled asthma week (WCAW).

RESULTS

The odds ratio for achieving a WCAW did not differ between the FD regimens; however, during the open period, budesonide/formoterol AMD increased the odds of achieving a WCAW vs. budesonide/formoterol FD (odds ratio 1.335; 95% CI: 1.001, 1.783; p = 0.049) despite a 15% reduction in average study drug use. Budesonide/formoterol AMD patients had a lower exacerbation rate over the study: 40% lower vs. salmeterol/fluticasone FD (p = 0.018); 32% lower vs. budesonide/formoterol FD (NS). During the double-blind period, there were no clinically relevant differences between the budesonide/formoterol FD and salmeterol/fluticasone FD groups. Budesonide/formoterol AMD patients used less reliever medication in the open extension: 0.58 vs. 0.92 occasions/day for budesonide/formoterol FD (p = 0.001) and 0.80 occasions/day for salmeterol/fluticasone FD (p = 0.011).

CONCLUSIONS

Adjustable maintenance dosing with budesonide/formoterol provides more effective asthma control by reducing exacerbations and reliever medication usage compared with fixed-dose salmeterol/fluticasone.

An update on asthma management

Asthma remains a major cause of morbidity in the Australian community, despite enhanced strategies and interventions for achieving optimal outcomes. Although there is some evidence of over use of high doses of inhaled corticosteroids (ICS), there is also evidence for under use of ICS, despite long-term data demonstrating clear benefits of low doses. The present paper briefly discusses some of the issues that are pertinent to the development of sensitization and atopic disease, but focuses mainly on the current understanding of best clinical practice for adults with asthma and the optimal approach to management. A clear definition of asthma control and a systematic approach to down-titration to minimize ICS doses is crucial to achieving better outcomes. Patient self-management education and optimal therapy are the keys to achieving better outcomes, although uncertainty remains about recommendations for mild asthma, despite new data.

Development of an economic model to assess the cost effectiveness of asthma management strategies

BACKGROUND AND OBJECTIVE

Asthma is a chronic-episodic disease characterised by acute, symptomatic episodes of varying severity. We developed a Markov model that can be used to estimate the cost effectiveness of alternative asthma treatments. Because of the costs they incur, asthma exacerbations ('attacks') requiring intervention by a healthcare professional were a central consideration in the development of the model.

METHODS

Treatment success was assessed as asthma control, a composite measure based on goals defined in world-wide asthma management guidelines and in terms of quality-adjusted life-years (QALYs). The data from which the transition probabilities were derived came from patients with asthma who received either salmeterol/fluticasone propionate combination (SFC) 50/100microg or fluticasone propionate (FP) 100microg, administered twice daily via an inhaler, in a 12-week, randomised, double-blind, clinical trial. Costs were estimated from resource profiles defined for each of the model states. A key aspect of the model was the use of probabilistic sensitivity analysis techniques to examine the uncertainty in the cost-effectiveness results. Distributions were fitted to transition probabilities and to cost input parameters and values were sampled at random from these distributions using a second order Monte Carlo simulation technique. This produced a distribution for incremental cost effectiveness that was employed to construct 95% uncertainty intervals and to construct cost effectiveness acceptability curves.

RESULTS

In this analysis, the model was run over a 12-week period using transition probabilities derived from the trial data. The results showed that treatment with SFC resulted in a higher proportion of successfully controlled weeks per patient than treatment with FP (66 vs 47%), and higher mean weekly direct asthma management costs (pound sterling 15.77 vs pound sterling 11.83; 2000 values). The average incremental cost per successfully controlled week with SFC was pound sterling 20.83. Probabilistic sensitivity analysis showed that the 95% uncertainty intervals for the incremental cost-effectiveness ratio was - pound sterling 64.94 to pound sterling 112.66. In approximately 25% of cases, SFC was dominant (more effective and less costly), but in the remaining cases, it was both more effective and more costly. It was shown that if decision makers are willing to pay approximately pound sterling 45 for an additional successfully controlled week, SFC will be the more cost-effective strategy in this patient population for 80% of the time.

CONCLUSIONS

This is one of the first decision-analytic models of asthma to incorporate probabilistic sensitivity analysis techniques to explore uncertainty. The model's flexible yet standardised framework permits the cost effectiveness of alternative asthma management strategies in different healthcare settings to be established.

Using clinical measures of disease control to reduce the burden of asthma

Clinical treatment guidelines encourage physicians to select asthma treatment in order to achieve established clinical treatment goals. Treatment selected on this basis may have profound effects upon other outcomes, some of which, such as improvements in well-being and lifestyle, are of direct benefit to the patient, and others, such as utilisation of healthcare resources and productivity, are of benefit to society. There is, however, evidence that a large proportion of patients do not achieve the goals of asthma management, such as those appearing in the international guide produced by the Global Initiative on Asthma (GINA). Furthermore, evaluation of the individual guideline goals provides little indication of the level of overall control achieved in individual patients, in spite of the fact that overall or comprehensive control is likely to be of greater value to the patient than control of only limited aspects of the disease. To give an indication of overall asthma control, and assess whether it is possible to reach this target, the GINA goals of asthma management have been amalgamated into a composite measure of overall asthma control. This approach has been used to assess recent clinical trials with the fluticasone propionate plus salmeterol combination given through a single inhaler compared with alternative treatment approaches. The studies showed that overall asthma control can be achieved, but at the fixed treatment doses used in clinical trials by only about half of the patients. Once such measures of control are included in management guidelines, healthcare professionals may need help to ensure implementation, using methods such as educational programmes and computerised disease management programmes. Improving asthma control in this way is likely to be associated with significant economic benefits.