Subacute lack of asthma control as a predictor of subsequent acute asthma exacerbation in a managed care population.

Objective: To evaluate whether an assessment of subacute lack of asthma control (SALAC) predicts subsequent acute asthma exacerbation (AAE).

Methods: This retrospective administrative claims study used medical and pharmacy claims from the HealthCore Integrated Research Database to identify patients aged 6 to 64 years with asthma and having 3 years' continuous enrollment from January 1, 2003, through December 31, 2005. Methods: Study inclusion criteria were at least 2 outpatient visits or at least 1 hospitalization or emergency department (ED) visit with an asthma diagnosis (International Classification of Diseases, Ninth Revision, Clinical Modification code 493.xx) in at least 1 of 3 years (2003-2005). SALAC was defined as more than 4 asthma outpatient visits or more than 5 short-acting beta2-agonist (SABA) prescriptions per year, and AAE was defined as at least 1 hospitalization or ED visit with a primary asthma diagnosis or an oral corticosteroid burst prescription. Generalized estimating equations modeled the risk of subsequent-year AAE as a function of 2 sets of variables to determine the independent effect of prior-year SALAC and its components on subsequent-year AAE. The first set included age, sex, geographic region, prior year AAE, and prior-year SALAC. The second set included age, sex, geographic region, prior-year AAE, high prior-year SABA use, and frequent prior-year asthma outpatient visits.

Results: Of 35,806 patients with asthma, 46.6% were male, and 35.8% were younger than 18 years. The mean annual prevalence of SALAC was 12.1%. Controlling for all other variables, the generalized estimating equation results indicate that prior-year SALAC is associated with a 60% increased risk of subsequent-year AAE (P <.001). Increased prior-year asthma outpatient visits and SABA use are associated with 34% and 85%, respectively, greater risks of subsequent-year AAE (P <.001 for both).

Conclusions: SALAC and its components can aid in predicting patients at risk for AAE.