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Asthma Quality-of-Care Markers Using Administrative Data^*

^* From the Department of Allergy (Drs. Schatz, Crawford, and Mendoza), Pharmacy Analytical Services (Dr. Nakahiro), and Care Management Institute (Drs. Mosen and Stibolt), Kaiser-Permanente Medical Center, San Diego, Los Angeles, and Oakland, CA.

Correspondence to: Michael Schatz, MD, MS, FCCP, Department of Allergy, Kaiser-Permanente Medical Center, 7060 Clairemont Mesa Blvd, San Diego, CA 92111; e-mail: michael.x.schatz{at}kp.org

	Abstract

TOP Abstract Introduction Materials and Methods Results Discussion References

 
Study objective: To evaluate the relationship of potential asthma quality-of-care markers to subsequent emergency hospital care.

Design: Retrospective administrative database analysis.

Setting: Managed care organization.

Patients: Asthmatic patients aged 5 to 56 years of age.

Interventions: None.

Measurements and results: Candidate quality measures included one or more or four or more controller medication canisters, a controller/total asthma medication ratio of 0.3 or 0.5, and the dispensing of fewer than six ß-agonist canisters in 2002. Outcome was a 2003 asthma emergency department visit or hospitalization. Multivariable analyses adjusted for age, sex, and year 2002 severity (based on utilization). In the total sample (n = 109,774), one or more controllers (odds ratio, 1.35) and four or more controllers (odds ratio, 1.98) were associated with an increased risk of emergency hospital care, whereas a controller/total asthma medication ratio of 0.5 (odds ratio, 0.73) and the dispensing of fewer than six ß-agonist canisters (odds ratio 0.30) were associated with a decreased risk. After adjustment for baseline severity in the total asthma sample, the controller/total asthma medication ratio (odds ratio, 0.62 to 0.78) and ß-agonist measure (odds ratio, 0.42) were associated with decreased risk, whereas the dispensing of four or more canisters of controller medication was associated with increased risk (odds ratio, 1.33). After stratification by year 2002 ß-agonist use, all of the measures were associated with decreased risk in those who received fewer than six ß-agonist canisters, whereas all of the measures except the medication ratio of 0.5 were associated with increased risk in the cohort who received six or more ß-agonist canisters.

Conclusion: Controller use and ß-agonist use may function as severity indicators in large populations rather than as asthma quality-of-care markers. A medication ratio of 0.5 appeared to function as the best quality-of-care marker in this study.

Key Words: asthma emergency department visits • asthma hospitalizations • asthma medication • asthma quality measures • population management

	Introduction

TOP Abstract Introduction Materials and Methods Results Discussion References

 
Asthma is an extremely common chronic illness that imposes a large human and economic cost on our society.¹² Since 1991, national asthma treatment guidelines have been promulgated in this country,³ setting the expectation that asthma can usually be controlled. However, despite these guidelines, the available data suggest that asthma remains inadequately controlled in most patients.⁴⁵⁶

Managed care organizations and others have attempted to improve asthma outcomes through the use of asthma quality-of-care or performance measures. The most widely used asthma quality-of-care measure is the one developed by the National Committee for Quality Assurance to evaluate the performance of health plans, the Health Employer Data and Information Set (HEDIS) measure.⁷ This measure identifies patients with "persistent asthma" based on administrative data criteria and then evaluates the proportion of these patients who receive at least one canister of a controller medication the following year. However, one recent study⁸ has shown that patients from the HEDIS persistent asthma population who received controller therapy that was defined in this way were actually more likely to experience subsequent emergency department (ED) visits or hospitalizations for asthma. This is presumably because any (vs no) controller therapy is more a marker of severity than effective therapy in the HEDIS population. Consistent with this hypothesis are the observations that the use of four or more controller medication canisters per year were necessary to be associated with significantly decreased asthma mortality⁹ or emergency hospital care.¹⁰

A second potential measure of adequate asthma therapy that has been evaluated is the ratio of controller medication to reliever or total inhaled asthma medication, but the data have been conflicting. Aveyard,¹¹ Griffiths et al,¹² and Gottlieb et al¹³ observed a correlation between prescribing practices, as measured by the ratio of therapy with controller medication to therapy with reliever medication, and emergency asthma admission rate, whereas Shelley et al¹⁴ observed no correlation between the hospital admission rate for asthma and the controller medication/reliever medication ratio. Studying this ratio in individual patients, Fuhlbrigge et al¹⁵ reported an inverse relationship between this ratio and the risk of subsequent asthma ED visits but only in children to whom fewer than four canisters of reliever medication were dispensed per person per year. Finally, one study¹⁶ has shown that patients who use fewer than six ß-agonist canisters per year are less likely than patients who are prescribed six or more ß-agonist canisters per year to experience subsequent emergency hospital care. This suggests that the number of ß-agonist canisters dispensed may be a useful performance measure that reflects quality asthma care.

The purpose of this study was to evaluate these potential asthma quality-of-care measures in a single large managed care population. This study also explores the effect of varying the asthma population definition and adjusting for baseline asthma severity on the performance of these measures.

	Materials and Methods

TOP Abstract Introduction Materials and Methods Results Discussion References

 
This study was approved by the Southern California Kaiser Permanente Institutional Review Board. The data for this study were derived from the Southern California Kaiser-Permanente asthma database, which is based on the linkage of computer data from a hospital discharge database, an outpatient diagnosis and procedures database, a membership database, and a prescription database. Patients are identified as having asthma if they met one or more of the following criteria in the prior 12 months: (1) any hospital discharge diagnosis (principal or other diagnosis) of asthma in the hospitalization database (International Classification of Diseases, Ninth Revision, code, 493.xx); (2) the dispensing of two or more asthma-related dispensings (excluding oral steroids) in the prescription database, including ß-agonists (excluding oral terbutaline), inhaled steroids, other inhaled antiinflammatory drugs, and oral leukotriene modifiers; and (3) an asthma-related visit to the ED or regular clinic listed in the diagnosis and procedures database.

This algorithm is based on the evidence that identifying "physician-diagnosed asthma" is a valid way to identify asthmatic patents in epidemiologic studies.¹⁷ Physician-diagnosed asthma is captured explicitly by criteria 1 and 3 and implicitly with criterion 2.

The subjects in the present cohort were patients aged 5 to 56 years (to conform to the National Committee for Quality Assurance HEDIS population) who were included in the asthma database during both 2002 and 2003. A subset of these patients was defined as having active asthma, based on the following additional criteria in 2002: (1) one or more hospitalizations or ED visits due to asthma; and (2) the dispensing of four or more asthma medication canisters (ie, short-acting or long-acting ß-agonists and inhaled antiinflammatory agents) or oral medications (ie, leukotriene modifiers), excluding oral corticosteroids (which may have been used for illnesses other than asthma) and theophylline (for which specific information was not available in this database). The outcome of interest was emergency hospital utilization for asthma during the year 2003, defined as at least one hospitalization or ED visit for asthma (International Classification of Diseases, ninth revision, code 493.xx), which was expressed as a yes/no variable.

The following candidate surrogates for quality asthma care in 2002 were evaluated as predictors of emergency hospital care in 2003 in both the total and active asthma populations. First, the dispensing of any controller medication, which is the current HEDIS numerator measure. Oral or inhaled long-acting bronchodilators and oral prednisone were excluded for the following reasons: (1) we did not have specific information regarding oral bronchodilators in this database; (2) inhaled long-acting bronchodilators are not considered to be appropriate controller therapy by HEDIS criteria⁷; and (3) oral corticosteroids are most often used as rescue therapy, not controller therapy, and are also not considered to be appropriate controller therapy by HEDIS criteria.⁷

The second candidate surrogate was four or more weighted canisters of controller medications. The weights were based on the potency of the medication and the number of doses per container, and they excluded oral or inhaled long-acting bronchodilators and oral prednisone. The specific weighting algorithm for individual products is available from the authors by request.

The third candidate surrogate was the weighted controller medication/total inhaler medication ratio of 0.3. The ratio was calculated for each patient as the number of weighted controller medication canisters that were dispensed during 2002 divided by the sum of the weighted controller medication and rescue inhaler canisters dispensed during 2002.

The fourth candidate surrogate was a weighted controller medication/total inhaler medication ratio of 0.5. The last candidate surrogate was the dispensing of fewer than six weighted canisters of short-acting ß-agonists per year.

Multivariable analyses were adjusted for age, gender, and 2002 asthma severity, based on the following criteria: (1) the occurrence of at least one ED visit or hospitalization due to asthma; (2) the dispensing of > 14 short-acting ß-agonist canisters; and (3) the dispensing of any oral corticosteroids. These three severity measures have been shown to be independent predictors of subsequent asthma emergency hospital care in this population.¹⁸

All of the analyses were conducted using a statistical software package (SAS, version 8.2 for Windows; SAS Institute; Cary, NC). Hypothesis testing for binary variables in unadjusted analyses was performed by means of ² analysis. Multivariable analyses were conducted using multiple logistic regression analyses. Hypothesis testing in logistic regression models was performed by means of the Wald ² test. A two-sided p value of < 0.05 was considered to be statistically significant in univariate and multivariable analyses.

	Results

TOP Abstract Introduction Materials and Methods Results Discussion References

 
The total study asthma population included 109,774 subjects, whose mean (± SD) age was 25.5 ± 17.0 years and 54.4% of whom were women. The active asthma population included 38,433 subjects, whose mean age was 30.1 ± 16.9 years and 53.1% of whom were women. Patients in the active asthma populations were more likely to have received any controller medication or more than four canisters of controller medication and to have a controller/total asthma medication ratio of 0.3 or 0.5, but were less likely to have received fewer than six canisters of a short-acting ß-agonist in 2002 (Table 1 ). Patients in the active asthma cohort also had greater baseline asthma severity, as measured by emergency hospital care, ß-agonist overuse, and the requirement for therapy with an oral steroid in 2002 (Table 1). Patients with active asthma were significantly more likely than patients who did not meet the criteria for active asthma to have utilized emergency hospital care in 2003 (6.6% vs 2.1%; p < 0.0001).

Because of the difference in prognosis between patients dispensing six or more canisters of short-acting inhaled ß-agonists compared with those dispensing fewer than six canisters, we stratified the results using the other therapy markers by this level of ß-agonist use in the active asthma population (Table 4 ). In patients receiving fewer than six ß-agonist canisters per year, all of the therapy markers were associated with reduced emergency hospital care in year 2003. However, in patients receiving six or more canisters of a short-acting ß-agonist, therapy markers (ie, use of any controller medication, use of four or more canisters of controller medication, or a controller/total asthma medication ratio of 0.3) either increased or did not significantly affect (controller/total asthma medication ratio, 0.5) the rate of emergency hospital care in 2003. This suggests that only a controller/total asthma medication ratio of 0.5 reflects enough of a therapeutic effect to cancel out the disease severity reflected by higher medication use.

	Discussion

TOP Abstract Introduction Materials and Methods Results Discussion References

The current study suggests that the dispensing of fewer than six ß-agonist canisters per year is a better measure of prognosis than are measures of controller medication use or controller medication/total medication ratios, because it is associated with a greater reduction in emergency hospital care than the other measures. At first glance, then, it would seem that it would be a good quality measure, because, in addition to the above, it was not as dependent on the population definition or adjustment for baseline severity as the other measures. However, the fact that none of the therapy markers seemed to reduce the risk of emergency hospital care in patients receiving six or more ß-agonist canisters per year suggests that it may be more of a severity marker than a marker of effective therapy. As such, it would not be a good quality measure, because it would penalize health plans caring for populations of patients with more severe disease. The strengths of the current study include the large number of patients who were managed by a single integrated health-care system, the inclusion of both children and adults with adjustment for age and sex, the evaluation of several measures concurrently in the same population, the assessment of the effect of varying the denominator and adjusting for baseline severity, and the use of weighted canisters to adjust for medication potency.

The active asthma denominator used in this study differs from the HEDIS denominator in that it does not include outpatient visits as an entry criterion, it used the number of weighted canisters of inhaled medication that was received rather than the number of dispensing events, and it did not include the use of oral bronchodilators. The current active asthma denominator appeared to function better than the HEDIS denominator, because controller therapy was associated with reduced emergency hospital care among the active asthma patients in this study (although not among the total patient population), whereas it was associated with increased emergency hospital care in a specific study of the HEDIS cohort⁸ (and in our total cohort). Unfortunately, we did not have outpatient visits due to asthma in our data set or data on therapy with oral long-acting bronchodilators to be able to create an exact HEDIS denominator. However, < 1% of our patients enter the HEDIS denominator because of outpatient visit alone, and only approximately 1.5% of asthmatic patients in our system received oral bronchodilators as their only controller therapy (R. Nakahiro, PharmD; unpublished data, November 2004). Thus, the difference between our results and those using the HEDIS denominator⁸ may have to do more with using weighted canisters than with not including outpatient asthma visits or oral bronchodilators. We prefer not to use the term persistent asthma to describe our active asthma population, because the term persistent asthma has a specific clinical definition³ for which validated administrative criteria do not exist.

In this study, any controller use was associated with reduced emergency hospital care only in the active asthma sample. One reason for this may be that the prescribing of any controller medication (as opposed to no prescribing of controller medication) reflects increased disease severity in an unselected sample of asthma patients and that one needs to account for adherence to therapy for controller medication use to function as a measure of adequate therapy in such a population. For example, Suissa et al ⁹ showed that asthma mortality was increased in patients using one canister of inhaled steroids per year and that the use of four or more canisters was required before asthma deaths were significantly reduced. Similarly, we have shown that the use of four or more canisters of inhaled steroids is required to reduce the occurrence of subsequent emergency hospital care in a general asthma population.¹⁰ However, in this study, the use of four or more canisters of controller medication did not appear to have any advantages as a quality marker over the use of any controller medication and actually appeared to function as an independent severity marker when adjusting for baseline severity. Thus, whereas any controller use was not associated with subsequent emergency hospital care in the total population and reduced it in the population of patients with active asthma, the use of four or more canisters of controller medication increased the risk in the total population and did not reduce it in the active asthma population (Table 3). These data also suggest that a subset of patients receiving four or mores canisters of controller medication need even more intense or different therapy in order to improve outcomes.

A controller/total asthma medication ratio of 0.5 was necessary to demonstrate a therapeutic effect in both the total population and the population of patients with active asthma. A ratio of 0.3 was related to decreased hospital use only after adjusting for baseline severity (ie, active asthma sample or multivariable adjustment). However, in the patients receiving six or more ß-agonist canisters, a ratio of 0.3 actually increased the risk of subsequent emergency hospital care, whereas a ratio of 0.5 neither increased or decreased the risk. This is consistent with the results of Fuhlbrigge et al¹⁵ who found that baseline disease severity influenced the value of the ratio measure such that it could only be demonstrated to reduce the risk in patients with milder disease (ie, baseline ß-agonist use fewer than four canisters per year).

What are the implications of these data regarding a quality of care for asthma performance measure? We believe that two possibilities are supported by the results of the current study. One would be to use a controller/total medication ratio of 0.5, because this measure was associated with a reduced risk of emergency hospital care in all of the analyses, except in patients receiving six or more canisters of a ß-agonist, in whom it was the only marker not associated with increased risk. We think that this would be reasonable, as long as the denominator accurately reflected patients with persistent asthma who required controller therapy. An alternative approach supported by the current data would be to stratify the population based on ß-agonist canister use. In patients to whom fewer than six canisters were dispensed, any of the therapy markers evaluated in this study appeared to work equally well. In those patients who received more than six ß-agonist canisters, only a controller/total medication ratio of 0.5 reflects enough of a therapeutic effect that it cancels out the severity indicated by increased medication use.

There are several potential limitations of the current study. The dispensing of medication does not necessarily equal the use of medication, although computerized pharmacy records are being increasingly utilized to assess patient adherence to medications.¹⁹²⁰ Some patients may not have prescription benefits, and, thus, the current data would misclassify them regarding both active asthma and performance measures. However, > 90% of asthmatic patients using Kaiser Permanente have prescription drug coverage (R. Nakahiro; unpublished data; November 2004), so the effect of such a misclassification should be small. Similarly, some patients may have had ED visits or hospitalizations in outside hospitals, although we have attempted to capture such outside utilization in our databases, and, thus, the amount of uncaptured data on such utilization should be small. Finally, although these data were collected in Southern California, we think the results should be generalizable, at least to demographically similar samples.

In summary, we have shown that ß-agonist measures appear to be better predictors of subsequent emergency hospital utilization than the current HEDIS measure (ie, any controller use), the use of more than four canisters of controller medication, or a controller/total asthma medication ratio measure. However, this measure may reflect severity more than adequate therapy and may, thus, not be a good quality-of-care measure. A controller/total medication ratio of 0.5 may be the best measure of adequate therapy in patients with persistent asthma. Additional studies will be necessary to confirm these results in additional populations and to show that this measure is also related to other measures of optimal clinical asthma care, especially correlates of the control of chronic asthma.

	Footnotes

 
Abbreviations: ED = emergency department; HEDIS = Health Employer Data and Information Set

Received for publication January 6, 2005. Accepted for publication February 25, 2005.

	References

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