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Monday, August 1, 2011

Using large population metrics to improve asthma outcomes

In this month’s issue, Schatz and Zeiger (J Allergy Clin Immunol 2011;128: 273-277) bring us validation results comparing administrative and clinical tools for assessing asthma outcomes from a Kaiser Permanente patient population. They describe their assessment experience in two primary areas: population management and quality of care.

The authors look at three elements of population management, beginning with the definition of persistent asthma. They use the modified, 2-year (current year and previous year) Health Effectiveness and Data Information Set (HEDIS) and compare it to a 2007 patient survey based on the EPR3 clinical definition. Schatz and Zeiger find that the majority of patients with HEDIS-defined persistent asthma in 2006 reported clinically defined persistent asthma in 2007, demonstrating that 2-year HEDIS definition correlates well with the EPR3 definition. Next they assessed impairment based on comparison of the administrative data on SABA use in the past 12 months and telephone-implemented Asthma Control Test (ACT), again finding useful convergent and predictive correlation between the two. Lastly, they assessed administratively defined risk with clinical risk, correlating healthcare utilization in the past 12 months and pharmacy data, then evaluated the predictive power of several different asthma control questionnaires. Of note, Schatz and Zeiger find that any one asthma questionnaire was a sensitive as the others for predicting exacerbation and suggest that using only one questionnaire is sufficient to detect risk.

Finally, the authors address quality of care metrics and evaluate an administrative data outcome called the medication ratio measure, which is defined from pharmacy data as ratio of controller medications to total asthma medications (controllers + relievers) dispensed in a 12-month period. Their results show that patients with a ratio of 0.5 or higher were significantly less likely to require emergent hospital care and were more likely to report higher quality of life than patients with a ratio of less than 0.5.

In conclusion, Schatz and Zeiger comment that administrative outcome data and survey data appropriately reflect asthma severity, impairment, risk and quality of care in a large patient population. They note that generalizability of their findings may require additional research in order to capture disparities among specific populations. Further, they suggest that individual or group practitioners would benefit from the application of any single outcome measure validated in their large population study.

Dr. Schatz will be talking about this article as part of our next podcast, “Reducing Asthma Burden.” Look for it on starting August 15.

Validated strategies for decreasing the frequency of asthma exacerbations

Asthma exacerbations are extremely high risk for asthma patients and impose a great cost burden on healthcare providers. Perhaps equally important is the evidence that full symptomatic recovery from exacerbation can result, nevertheless, in persistent decreased lung function after recovery. To this issue, Paul O’Byrne inventories current therapies directed specifically at preventing or mitigating asthma exacerbations in this month’s issue (J Allergy Clin Immunol 2011;128: 257-263).

O’Byrne notes that exacerbations are thought to be precipitous, emergent events. In fact, they have a gradual development over approximately a week as symptoms increase and lung function decreases until the point of urgent intervention. Additionally they are frequently associated with upper respiratory infections (URI) caused typically by human rhinovirus (HRV) or allergen exposure in atopic patients. The author notes that URI or allergen exposure alone is not sufficient to elicit exacerbation and other conditions are required, therefore, prevention is targeted at risk mitigation.

The author discusses inhaled corticosteroids (ICS) as the primary intervention aimed at reducing airway inflammation, and subsequently, risk of infection or reactivity. ICS have a positive effect on airway eosinophilia, a primary cause of inflammation, but O’Byrne notes that slightly less than half of asthma patients have airway neutrophilia that doesn’t respond to ICS therapy. Symptom rescue is managed through use of short- and long-acting bronchodilators, used separately or in steroid + long-acting bronchodilator combination products. O’Byrne comments on recent research supporting the use of the combination product budesonide + formoterol for maintenance as well as exacerbation, noting that budesonide + formoterol was as effective as oral steroids for common outcomes, such as nighttime awakenings and albuterol rescue use.

O’Byrne discusses the beneficial effects of anti-leukotriene therapy, especially in pediatric asthma patients. Anti-IgE antibody therapy is helpful in allergic asthma and inner city children with asthma, though anti-IL-5 antibody therapy for reducing airway eosinophilia in refractory asthma has not yet proven unequivocally beneficial. Finally, the author discusses bronchial thermoplasty for refractory asthma, which has approval in only a few countries.

Editor's note: Readers interested in learning more about asthma exacerbations may want to consult the August 2009 supplement, Supplemental Recommendations for the Management and Follow-up of Asthma Exacerbations, written by representatives of the American Academy of Allergy, Asthma & Immunology, the American Academy of Emergency Medicine, and the American Thoracic Society. The supplement is available for free download at: