Original article
Asthma, lower airway disease
Short-acting β-agonist use and its ability to predict future asthma-related outcomes

https://doi.org/10.1016/j.anai.2012.08.014Get rights and content

Abstract

Background

Short-acting β-agonist (SABA) use is well established in predicting asthma events in adults. However, this predictive ability has yet to be established in a pediatric population together with an assessment of amount of use.

Objective

To identify the number of SABA canisters that best predicts future asthma-related exacerbations and the optimal length of time for measurement of SABA use in pediatric and adult asthma patients.

Methods

Asthma patients were identified from a Medicaid and a commercially insured database (January 1, 2004, through December 31, 2005, and January 1, 2004, through June 30, 2006, respectively). Following the date of first asthma medication, an assessment period (3, 6, or 12 months) was used to measure SABA use. Asthma-related exacerbations were identified in the subsequent 12-month period. Receiver operating characteristic curve analyses and logistic regression were used to select the critical values of SABA use and optimal assessment periods and to conduct incremental analysis, respectively.

Results

A total of 33,793 Medicaid and 101,437 commercial patients met the study criteria. Use of 3 or more SABA canisters during 12 months was identified in both pediatric Medicaid and commercial populations to best predict an increased risk of an asthma-related exacerbation. For adults, use of 2 or more SABA canisters was found as the critical value with shorter optimal assessment periods of 3 and 6 months. Each additional SABA canister resulted in an 8% to 14% and 14% to 18% increase in risk of an asthma-related exacerbation in children and adults, respectively.

Conclusion

The study identified critical values of SABA use that predict future asthma events. Each additional SABA canister predicted increases in exacerbation risk in children and adults.

Introduction

Asthma is a common, chronic disease in the United States, with more than 22 million people diagnosed as having the condition in 2009.[1], [2] Sudden increases in severity of its symptoms may require emergency care or a hospitalization.1 Asthma symptoms are often managed using long-term controller medications and quick-relief medications.3 Short-acting β-agonists (SABAs) are used to provide prompt symptomatic relief.[4], [5], [6]

Asthma management techniques often use quality-of-care measures, developed using administrative claims data, which are helpful in predicting subsequent asthma-related outcomes.[7], [8], [9], [10] One such measure is SABA dispensing to identify high-risk patients. The SABA measure is ideal for risk stratification because SABAs are used as rescue medications and elevated SABA use is considered a sign of uncontrolled asthma.3 Long-term (controller) asthma medications may prevent future asthma-related adverse outcomes.

SABA use, as a predictor of future asthma-related outcomes, usually has been measured during assessment periods of 3 or 12 months.[8], [9], [11], [12] The length of assessment periods affects the SABA threshold as a risk marker.

The predictive ability of SABAs has been assessed to a limited extent in pediatric and Medicaid populations.[9], [11], [13], [14], [15] The need for additional investigation is justified because of a high prevalence of asthma in children. More than 25% of Americans with asthma are children.2 Further, Medicaid patients—who tend to be of lower socioeconomic status, younger age, and female sex—have increased likelihood of experiencing asthma-related adverse events.[16], [17], [18], [19], [20] In addition, Medicaid patients are reported to have poorer asthma control compared with those with private insurance or those who are uninsured.20

The study objective was to assess whether SABA dispensing can be used to predict future asthma outcomes in children and adults in Medicaid and commercial populations. This study explored the critical number of SABA canisters and the optimal time during which SABA use should be measured in relation to asthma exacerbation risk. In addition, it evaluated the incremental effect on the risk of asthma outcomes with each additional SABA canister.

Section snippets

Study design and population

This study had a retrospective cohort design and used two claims databases: the Ingenix Impact National Managed Care Database (commercial) and the MarketScan Medicaid Database (Medicaid). January 1, 2003, through June 30, 2008, data were used from the commercial database, and January 1, 2003, through December 31, 2007, data were used from the Medicaid database. The commercial database used the integrated medical and pharmacy administrative claims of more than 98 million lives from more than 46

Results

The sample that met study criteria consisted of 33,793 Medicaid patients (25,048 children and 8,745 adults) and 101,437 commercial patients (41,753 children and 59,684 adults). A demographic description of the study sample is provided in Table 1. Approximately two-thirds of the pediatric and three-fourths of the adult sample were using 1 or more SABA canister in all assessment periods in both the Medicaid and commercial populations (Table 2), respectively.

Discussion

The current study assessed the role of SABA use to predict subsequent asthma-related outcomes. Approximately a 2-fold increase in the risk of an asthma-related hospitalizations or an ED visit in the subsequent year for both the Medicaid and commercial populations was noted for patients using 3 or more SABA canisters per year (children) and 2 or more SABA canisters (adults) per quarter when compared with patients using fewer than 3 and fewer than 2 SABA canisters, respectively.

Our findings are

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    Disclosures: Dr Stanford is an employee of GlaxoSmithKline (GSK) and owns company stock. Dr Schatz has received research grant support from GSK and has also served as a research consultant for GSK. Dr Shah, Dr D’Souza, and Mr Dhamane are employees of Xcenda LLC, a company that received funding from GSK to conduct this research.

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