How Well Do the HEDIS Asthma Inclusion Criteria Identify Persistent Asthma?

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The American Journal of Managed Care, October 2005, Volume 11, Issue 10

Objectives: (1) To determine if the Health Plan Employer Dataand Information Set (HEDIS) asthma inclusion criteria consistentlyidentify persistent asthma on a year-to-year basis and (2) to explorewhether variation in the number of years of qualification is associatedwith medication and resource utilization outcomes.

Study Design: Retrospective observational study.

Methods: We identified 132 414 patients in a large healthcareprogram who were included in 1 or more HEDIS persistent asthmacohorts between 1999 and 2002 and who had continuous insuranceand pharmacy benefit coverage for the entire 4-year observationperiod. Medication, emergency department, and hospital usein 2002 was identified using electronic claims and pharmacy information.

Results: Overall, 47.9% of the patients were identified as havingpersistent asthma in only 1 of 4 years, 40.8% had at least 2 consecutiveyears, and 28.2% had at least 3 consecutive years. Inbivariate and multivariate analyses, more consecutive years ofHEDIS persistent asthma qualification significantly increased thelikelihood of frequent short-acting β-agonist use, inhaled anti-inflammatorycorticosteroid use, at least 1 emergency departmentvisit, and at least 1 hospitalization. The strongest relationship wasfor 3 or more consecutive years of HEDIS qualification.

Conclusions: A significant portion of the HEDIS persistent asthmacohort does not qualify on a year-to-year basis, suggesting thatthe current 1-year qualification period or the underlying administrativecase definition for persistent asthma may be suboptimal.Further clinical validation studies are needed to determine theoptimal criteria for a more useful HEDIS persistent asthma casedefinition.

(Am J Manag Care. 2005;11:650-654)

Asthma is a chronic inflammatory lung disease.1There is no gold standard test for the diagnosis ofasthma. It is typically based on clinical symptomsand is ideally confirmed by the demonstration ofreversible airway obstruction or bronchial hyperreactivity.2 Clinical audits of asthma diagnoses have consistentlydemonstrated significant underdiagnosis andoverdiagnosis.3-6 The ability of administrative data systemsof most health plans to identify the diagnosis ofasthma is still unknown.

The current Health Plan Employer Data andInformation Set (HEDIS) measure for asthma uses administrativedata collected during 1 year to identifypatients with presumed persistent asthma and evaluatescontroller therapy during the next year. It has beenreported that this asthma case identification usingadministrative data in children cannot distinguish persistentasthma from transient wheezing syndromes.7 Itis also difficult to determine asthma severity usingadministrative data.8

One of the historical limitations of administrativedata from a single treatment center or healthcare networkis migration of patients into and out of the healthcareplan.9 Kaiser Permanente Health Care Programcares for a large group of patients year after year andcan provide multiyear data to evaluate asthma prevalenceand persistence. Vollmer and coworkers,10 in theKaiser Permanente Northwest Region, recently publishedan article on asthma prevalence using multipleclinical information systems. They found that asthmacase identification based on 1 year of pharmacy datawould capture only 61% of the prevalent asthma casesand that the electronic health record alone would identifyonly 66% of the total asthma cases.

Despite the clinical limitations of administrative datato define persistent asthma, such data are available tomost health plans and are potentially useful from a qualityof care perspective. Identifying poor performance onthe HEDIS measure for asthma can be used to targetquality improvement and outreach efforts.

Because few reliable and valid assessment tools existto diagnose persistent asthma, further efforts are neededto improve administrative methods to define persistentasthma. A limitation of the current HEDIS asthmainclusion criteria is the inclusion of a significant portionof patients with intermittent asthma, based on a 2-yearanalysis.11 As a result, it will be important to developmore robust administrative measures so that chronictreatment can be directed to those who will benefit fromit and so that health plans that provide the best care arerewarded.12

With this background in mind, the present study hasthe following 2 general objectives: (1) to evaluate theoccurrence of persistent asthma on a year-to-year basisas defined by the current HEDIS measure for asthmaand (2) to explore whether alteration of the administrativedefinition of persistent asthma results in the identificationof a population that uses more asthma-relatedhealthcare, including medication use and resource utilization,which are likely markers of persistent asthma.


Case Identification

We identified 132 414 patients with persistent asthmaaged 5 to 56 years who qualified in at least 1 of 4HEDIS persistent asthma cohorts identified from 1999through 2002. The sample was drawn from patientsreceiving care from Kaiser Permanente Health CareProgram, a large vertically integrated staff-modelhealthcare system. Computerized data from patientswith persistent asthma were drawn from the following4 geographic regions: northern California, southernCalifornia, Colorado, and the Pacific Northwest (northwestOregon and southwest Washington).

Patients were selected based on 3 inclusion criteria.First, patients had to meet 1 or more of the followingcurrent HEDIS criteria for persistent asthma caseidentification during at least 1 of the years observed:(1) at least 4 asthma medication-dispensing events,(2) at least 2 asthma medication-dispensing eventsand 4 asthma-related outpatient visits, (3) at least 1asthma-related hospitalization, or (4) at least 1 asthma-related emergency department (ED) visit. Second,patients were required to maintain continuous insuranceand pharmacy benefit coverage during the entirestudy period (January 1, 1999, through December 31,2002). Third, patients had to stay within the HEDIS-eligibleage range of 5 to 56 years for the entire durationof the study. If patients aged out during the 4-yearobservation period, they were excluded from the studypopulation.

Primary Independent Variable of the Number ofYears of HEDIS Qualification

The number of years of HEDIS qualification was theprimary independent variable. This variable was categorizedinto the following 6 mutually exclusive groups: 1year only, 2 nonconsecutive years, 2 consecutive years,3 nonconsecutive years, 3 consecutive years, and 4consecutive years.

Outcome Measures of Medication Useand Resource Utilization

Medication and resource utilization data were evaluatedduring 2002. Data on the use of weighted canisterequivalents of inhaled anti-inflammatory corticosteroidsand short-acting β-agonists were collected fromelectronic pharmacy databases. The calculation ofweighted canister equivalents was based on drug potencyand doses per canister (available from the author).Resource utilization included 1 or more asthma-relatedED visits and hospitalizations during 2002. Both measureswere collected from electronic databases.

Statistical Analysis

All analyses were conducted using the StatisticalPackage for the Social Sciences (SPSS version 11.1;SPSS Inc, Chicago, Ill). Descriptive statistics were calculatedoverall and stratified by pediatric and adult populationsfor demographic variables, number of years ofHEDIS qualification, medication use, and resource utilization.We then examined the method of entry intothe HEDIS persistent asthma cohort by the number ofyears of HEDIS qualification. Next, we examined thebivariate association of consecutive years of HEDISqualification with medication and resource utilization,using the c2 test. Finally, logistic regression models wereconstructed to examine the independent association ofthe number of consecutive years of HEDIS qualificationwith medication and resource utilization, adjusting forage, sex, and geographic region.


A total of 216 025 patients had membership in atleast 1 HEDIS persistent asthma cohort between 1999and 2002. Of those, 146 531 (67.8%) maintained continuousinsurance and pharmacy benefit coverage forthe entire 4-year observation period (data not shown).There were 132 414 patients (90.4%) with continuousinsurance and pharmacy benefit coverage whoremained within the HEDIS-eligible age range for theentire observation period. The total health plan populationwithin the age cutoffs with continuous insuranceand pharmacy benefit coverage was 2 224 804 patients.The HEDIS-defined patients with persistent asthmathus accounted for 6.0% of the health plan population.

Overall, the study population included slightly morefemales (55.0%), with less female representation in thepediatric population and greater female representationin the adult population (Table 1). About half of thestudy population qualified during only 1 of the 4 yearsobserved, slightly more for the pediatric populationand slightly less for the adult population. Overall, 40.8%had at least 2 consecutive years of HEDIS qualification,and 28.2% qualified during 3 or more consecutive years.A higher proportion of adults maintained 2 or moreyears of HEDIS qualification compared with children.

Within the pediatric population, most patientsentered the HEDIS persistent asthma cohort each yearthrough medication use alone (range, 71.3%-79.9%) orthrough medication use in combination with 1 or moreof the other entry criteria (range, 91.9%-94.3%). Aslightly higher proportion of the adult population qualifiedthrough medication use alone (range, 78.7%-85.5%), while a similar proportion qualified bymedication use in combination with other entry criteria(range, 93.9%-96.6%).

The number of consecutive years of HEDIS qualificationwas strongly associated with medication use inbivariate analysis (Table 2) and in multivariate analysis(Table 3) for the pediatric and adult populations. Inboth populations, those with 2 or more consecutiveyears of HEDIS qualification were more likely to use 1or more canister equivalents of inhaled anti-inflammatorycorticosteroids and to overuse short-actingβ-agonists (≥ 14 canister equivalents). As might be expected,in the multivariate comparison, those with 4consecutive years of HEDIS qualification were themost likely to use inhaled anti-inflammatory corticosteroidsand to overuse short-acting β-agonists, withthose with only 1 year of HEDIS qualification as the referentgroup (Table 3).

The number of years of HEDIS qualification was significantlyassociated with resource utilization, althoughthis association was not as strong as that found for medicationuse (Tables 2 and 3). For the pediatric and adultpopulations, those with 3 or more consecutive years ofHEDIS qualification were significantly more likely tohave asthma-related ED visits and hospitalizations comparedwith those with 1 year of HEDIS qualification(Table 3). Utilization of asthma-related ED visits andhospitalizations did not differ for those with 2 consecutiveyears of qualification compared with those withonly 1 year of qualification.


This study found that the current 1-year HEDIS qualificationperiod does not consistently capture the persistentasthma cohort on a year-to-year basis. Abouthalf of children and adults qualified for the persistentasthma cohort for only 1 of the 4 years observed.However, our results suggest that the manner in whichpatients entered the HEDIS persistent asthma cohortdoes not vary over time, with most children and adultsentering through the use of asthma medications.

Our findings suggest that at least 2 consecutive yearsof HEDIS qualification comprise a better qualificationperiod to identify persistent asthma. For the pediatricand adult populations,patients with2 or more consecutiveyears ofHEDIS qualificationwere significantlymore likelyto use any inhaledanti-inflammatorycorticosteroids andto overuse short-actingβ-agonists,which are likelymarkers of persistentasthma. Theoverall relationshipwith the numberof years ofHEDIS qualificationand the occurrenceof adverseevents was consistentwith medication use, but the critical point was 3 ormore consecutive years of qualification, rather than 2consecutive years. In addition, the multivariate resultssuggest that medication use is a more sensitive indicatorto detect differences in the number of consecutive yearsof HEDIS qualification compared with asthma-related EDvisits or hospitalizations.

These findings have implications for the manner inwhich the quality of asthma care is measured in theUnited States. Results indicate that a change from a 1-year qualification period in the HEDIS measure forasthma to a 2-year qualification period may be warranted.Such a change would likely reduce the numberof false-positive results in the current HEDIS denominator,which in turn would affect performance on theHEDIS numerator. With a more accurate denominatorthat reflects true persistent asthma, it is likely that therate of long-term controller use will increase and thatthere will be less variation in the HEDIS measure forasthma overall. The change to a 2-year qualificationperiod would not require additional resources from ahealth plan perspective, because the current windowexamines medication and resource utilization during a2-year period. Further analysis (data not shown) foundthat the HEDIS persistent asthma cohort would bereduced by about 30% when changing from the 1-yearqualification period to a 2-year qualification period.Therefore, it is likely that most health plans would beable to continue participating in the HEDIS measure forasthma and would not be affected by the reduction inthe persistent asthma cohort size.

Furthermore, if healthcare programs are encouragedto provide inhaled anti-inflammatory corticosteroids topatients with chronic asthma symptoms, there needs tobe a corresponding effort to ensure that these patientsactually have a condition that would be helped by regularuse of this therapy. Further random audits of actuallung function and bronchial hyperreactivity of patientsselected by the various current and future proposedadministrative measures for asthma are essential.6

This study had several limitations. First, the qualityand reliability of administrative pharmacy and resourceutilization data can vary across geographic regions andfacilities. Furthermore, the use of asthma qualificationmedications may also vary widely, affecting selection ofasthma patients in the HEDIS persistent asthma cohort.However, adjusting for geographic region in the multivariateanalysis in this study did not alter the results(Table 3). Second, no clinical assessments of asthmawere measured (eg, symptoms and forced expiratoryvolume in 1 second). Therefore, it is not entirely clearwhether the number of years of HEDIS qualification isassociated with clinically defined persistent asthma.Third, results can only be definitely applied to insuredpopulations receiving care in a large staff-model healthcareprogram, rather than to other delivery systems.

Future research is needed to validate the findings ofthis study. Specifically, further studies are needed toexamine the association of the number of years ofHEDIS qualification with clinical assessments of persistentasthma. Such work will further clarify the appropriatenumber of years of the qualification period thatassesses persistent asthma. Finally, further work isneeded to examine the effect of modifications to theduration of the HEDIS qualification period on overallperformance on the HEDIS measure for asthma andwhether findings are consistent across delivery systems.


We would like to acknowledge the following Kaiser Permanente HealthCare Program analysts whose dedication and effort made this study possible:Mary-Jean Clements, BSc, Doug Felton, MA, Corey Flohr, MHS, AiliGong, MS, Michael Nash, BS, and Nelli Tadevosyan, MPH.

From the Care Management Institute, Portland, Ore (DM, TS), and Oakland, Calif (JG,JB); Departments of Allergy, San Diego (EM, MS) and Vacaville (GM), Calif; KaiserPermanente Clinical Research Unit, Denver, Colo (JM); and Kaiser Permanente Centerfor Health Research, Portland (DM); Kaiser Permanente Health Care Program.

This work was supported by Kaiser Permanente Health Care Program.

Address correspondence to: David Mosen, PhD, MPH, Kaiser Permanente Centerfor Health Research, 3800 N Interstate Avenue, Portland, OR 97232.


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