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The American Journal of Managed Care December 2010
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Step-Up Care Improves Impairment in Uncontrolled Asthma: An Administrative Data Study
Robert S. Zeiger, MD, PhD; Michael Schatz, MD, MS; Qiaowu Li, MS; Feng Zhang, MS; Anna S. Purdum, PharmD, MS; and Wansu Chen, MS
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Step-Up Care Improves Impairment in Uncontrolled Asthma: An Administrative Data Study

Robert S. Zeiger, MD, PhD; Michael Schatz, MD, MS; Qiaowu Li, MS; Feng Zhang, MS; Anna S. Purdum, PharmD, MS; and Wansu Chen, MS

Significant clinically meaningful improvements in asthma impairment are documented by administrative data for 1 year after initiation of step-up care in patients with uncontrolled asthma.

Objective: To determine whether step-up care recommended by national asthma guidelines improves asthma control in a large managed care organization.

 

Study Design: Cohort analysis.

 

Methods: A cohort with uncontrolled asthma, defined as impairment or risk in a 1-year consecutive period, was identified using electronic medical records among continuously enrolled patients with asthma aged 12 to 56 years. Guideline-based step level of care was determined 3 months before and 3 months after the index event of uncontrolled asthma according to an algorithm of asthma medication dispensing using electronic pharmacy data. Impairment based on short-acting b-agonist canisters dispensed and risk based on asthma emergency or hospital care were compared during the following year in patients with vs without step-up care, adjusting for demographics, prior utilizations, asthma risk, and comorbidities.

 

Results: Uncontrolled asthma was identified in 7694 eligible patients (mean [SD] age, 35.7 [14.4] years; 54.0% female). Step-up care during the 3-month period after the uncontrolled asthma event was seen in 2160 of 7177 patients (30.1%) with classifiable step care. Step-up care was associated with significant reductions in impairment, with adjusted relative risks of 0.78 (95% confidence interval [CI], 0.73-0.85) during the first 6 months and 0.84 (95% CI, 0.78-0.90) during the full 12-month follow-up period. Emergency or hospital care was unaffected by step-up care. Subgroups with uncontrolled asthma defined by impairment only and risk only showed outcomes generally similar to those of the entire cohort.

 

Conclusion: Guideline-based step-up care in uncontrolled asthma was determined by administrative data and was shown to be associated with significant and clinically meaningful improvements in asthma impairment but not risk.

(Am J Manag Care 2010;16(12):897-906)

Determination of national asthma guideline-based step-up care in uncontrolled asthma by administrative data may be useful for improving quality of care in managed care organizations.

 

  • Step-up care after determination of uncontrolled asthma is documented in a minority of patients.

 

  • Greater improvement in the impairment domain (short-acting b-agonist canisters dispensed) of asthma control is seen in patients with uncontrolled asthma receiving step-up asthma care compared with those not receiving step-up asthma care.

 

  • Real-time determination of uncontrolled asthma by administrative data is recommended to identify patients in whom step-up asthma care is needed to improve asthma control.
Poor asthma control impairs health-related quality of life, increases resource utilization and cost, and persists as a major public health issue affecting more than 23 million individuals in the United States.1 In 2007, direct and indirect costs for asthma totaled $19.7 billion, with the cost of prescription drugs accounting for most of the direct medical expenses.1

The National Asthma Education and Prevention Program2 and the Global Initiative for Asthma3 (http://www.ginasthma.com) developed guidelines to improve asthma control and to reduce burden. These guidelines emphasize 2 major domains of asthma control: impairment and risk. Impairment refers to rescue medication use, symptoms, nocturnal awakenings, school and work absences, exercise problems, and pulmonary function. Risk addresses frequency and severity of exacerbations, loss of lung function, and adverse effects of medication. In addition, the guidelines established 6 step levels of treatment to implement based on a patient’s asthma severity determined before treatment or level of control determined after therapy is instituted. Additional evidence is needed to determine whether appropriate step-up care in patients with uncontrolled asthma improves asthma  control in large managed care organizations.

This study used administrative data to identify patients with uncontrolled asthma and their step level of care to determine whether step-up care is associated with improvements in subsequent asthma control. We hypothesized that step-up care instituted after a defined uncontrolled asthma event is associated with improvements in asthma control.

METHODS

Study Design

This institutional review board–approved retrospective cohort study was conducted using administrative pharmacy and utilization databases of health plan members of the Kaiser Permanente Southern California Region. The study design is shown in Figure 1.

Determination of the Cohort With Asthma. Patients were identified as having asthma if they met at least 1 of the following criteria4 in both 2005 and 2006: (1) any discharge diagnosis of asthma in the health plan and contracting hospital databases (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code 493.xx);(2) emergency department or outpatient asthma-related diagnosis; or (3) at least 2 asthmarelated drug dispensings (excluding oral corticosteroids) in the pharmacy database, including β-agonists (excluding oral terbutaline sulfate) and all asthma controller drugs.

Determination of the Cohort With Uncontrolled Asthma. Uncontrolled asthma was defined as impairment or risk in a 1-year consecutive period within the first 18 months (January 1, 2005, to June 30, 2006) of the entire 36-month study period (Figure 1).

Impairment was defined as at least 7 short-acting β-agonist (SABA) canisters dispensed in 1 year. In a clinical setting, asthma impairment is defined based on rescue therapy, symptoms, functional limitations, and pulmonary function2; however, only rescue therapy use can be obtained in administrative data. We validated the number of SABA canisters dispensed in 1 year as a long-term measure of asthma control because it correlates with patient-reported measures of asthma impairment.5 The SABA cut point of at least 7 canisters dispensed per year defined impairment because at least 70% more asthma control problems6 occurred in patients receiving at least 7 vs 6 or fewer canisters dispensed per year.5

Risk was captured by at least 2 unique exacerbations within a year. These included asthma-related emergency department visits or hospitalizations (emergency or hospital care was defined as a primary diagnosis of asthma [ICD-9-CM code 493.xx] or as a secondary diagnosis of asthma when the primary diagnosis was related to a respiratory disease) or oral corticosteroid courses with a provider visit for asthma within 2 days of dispensing.

The “index date” of uncontrolled asthma for impairment was the date of the seventh SABA canister dispensing, and the index date for risk was the date of the second exacerbation event during a consecutive 1-year interval within the first 18 months of the study. For patients with both impairment and risk events within the 1-year interval, the date of the last event was used as the index date to determine asthma step care (Figure 1).

Eligible study patients were health plan members aged 12 to 56 years who met the study definition of having uncontrolled asthma and from 2005 to 2007 were continuously enrolled and had health plan drug benefit. The eligible cohort is shown in Figure 2.

Step Care. Asthma drug dispensing was determined using the health plan pharmacy information management system,4 in which the prescription directions for use, specific drug class and name, and quantities dispensed are available. Daily dosage of inhaled corticosteroid was calculated as the following: ([No. of Canisters] × [No. of Puffs per Canister] × [Strength in Micrograms per Puff]) / No. of Days’ Supply).

Inhaled corticosteroids were categorized as low dose, medium dose, or high dose based on the calculated daily dosage and on their individual potency using the estimated comparative daily dosages recommended by National Heart, Lung, and Blood Institute guidelines2 for persons 12 years or older. Fluticasone propionate plus salmeterol (Advair) was the only combination inhaled corticosteroid and long-acting β-agonist therapy dispensed during step care determination. Strengths of Advair Diskus 100/50, 250/50, and 500/50 were categorized as low-dose, medium-dose, and high-dose inhaled corticosteroid, respectively.

Step level of care was determined using drug dispensing 3 months before and 3 months after the uncontrolled asthma index date based on guidelines for patients 12 years or older as follows2: (step 1) no drugs or only SABA dispensed; (step 2) monotherapy low-dose inhaled corticosteroid, leukotriene modifier, mast cell stabilizer, or theophylline; (step 3) (a) combination low-dose inhaled corticosteroid with longacting β-agonist, leukotriene modifier, mast cell stabilizer, or theophylline or (b) monotherapy medium-dose inhaled  corticosteroid; (step 4) (a) combination medium-dose inhaled corticosteroid with long-acting β-agonist, leukotriene modifier, mast cell stabilizer, or theophylline or (b) monotherapy high-dose inhaled corticosteroid; (step 5) high-dose inhaled corticosteroid plus long-acting β-agonist with or without omalizumab; and (step 6) high-dose inhaled corticosteroid plus long-acting β-agonist plus oral corticosteroid with or without omalizumab. Electronic medical records of patients in step 6 were reviewed to determine that the oral corticosteroid  dispensed was for maintenance therapy and not for acute use only. Patients were then divided into categories of step-up care or no step-up care based on whether the post–step care was at least 1 step level higher than the pre–step care level. Patients were considered unclassifiable and were excluded from the final analyses when pharmacy data did not allow step classification because of incomplete or missing information. Immunotherapy could not be captured accurately by our electronic databases during the time of the study. Only 4 patients were taking omalizumab during the study and therefore were of inadequate sample size to allow separate analysis.

Data Analysis

Patient Demographics. Patient characteristics were captured by administrative data (Table 1). Census block group levels of family household income and educational attainment estimates in 2006 were supplied by Nielsen Claritas (http://www.claritas.com) and were obtained for more than 95% of members through geocoding, a technique that links members’ addresses to census geographic areas.4 Databases did not capture smoking history or race/ethnicity during the study period.

Outcomes (Comparisons Between Step-Up Care vs No Step-Up Care). Impairment was defined as at least 7 SABA canisters dispensed in the full year5 or as at least 4 SABA canisters dispensed in months 0 through 6 after the 3-month post–step care period. Risk was defined as a severe asthma exacerbation requiring asthma emergency or hospital care during the first 6 months and entire year after the 3-month post–step care period. Asthma emergency or hospital care was selected as the risk outcome because it is more specific for asthma risk and represents more severe exacerbations than oral corticosteroid dispensing; furthermore, the latter is affected by its frequent prophylactic dispensing during routine visits to be used for future worsening asthma.

Statistical Analysis

Descriptive analyses for individual resource use items entered as a dichotomous variable (eg, ≥7 SABA canisters dispensed [yes or no]) or as a count variable (eg, the number of SABA canisters dispensed) were conducted to illustrate their association with step care. Counts and proportions were obtained for categorical variables, and the mean (SD) and median (range) were used for continuous variables. Bivariate associations were assessed as appropriate by t test, analysis of variance, χ2 test, or nonparametric methods (eg, Wilcoxon rank sum test and Kruskal-Wallis analysis of variance). Significance was set at 2-tailed P <.05.

Univariate and multivariate Poisson regression analyses with a robust error variance (SAS/GENMOD) were constructed to calculate the unadjusted and adjusted relative risk (RR) and the 95% confidence interval [CI] for the outcome variables, as this type of regression model provides better estimates in health investigations involving common binary outcomes (prevalence rate >10%) than logistic regression.7,8 All point estimates and 95% CIs were generated using SAS software (version 9.1 for Windows; SAS Institute, Cary, North Carolina).

The following covariates were available for selection for the multivariate models: (1) baseline variables, including age at the time of the uncontrolled asthma index event, sex, and geocoded educational and income attainment; (2) prior-year variables, including number of SABA canisters dispensed, asthma exacerbations (any asthma emergency or hospital care or any asthma oral corticosteroid dispensing determined9-11), total nonasthma emergency department visits and outpatient visits,4 allergy or pulmonary specialist visits,10,11 and comorbidities (gastroesophageal reflux disease, sinusitis, and nasal polyposis); and (3) the pre–index date step level of care. Covariates were selected according to Akaike  information criterion by means of stepAIC function in R statistical software version 2.9.0 (http://www.r-project.org).

RESULTS

Cohort With Uncontrolled Asthma

A total of 7694 patients aged 12 to 56 years with uncontrolled asthma were eligible for the study based on asthma impairment or risk definitions (Figure 2). Of these patients with uncontrolled asthma, 5529 (71.9%) were identified as having asthma impairment only, 1355 (17.6%) as having asthma risk only, and 810 (10.5%) as having both asthma impairment and risk.

 
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