The American Journal of Managed Care October 2005
How Well Do the HEDIS Asthma Inclusion Criteria Identify Persistent Asthma?
Objectives: (1) To determine if the Health Plan Employer Data and Information Set (HEDIS) asthma inclusion criteria consistently identify persistent asthma on a year-to-year basis and (2) to explore whether variation in the number of years of qualification is associated with medication and resource utilization outcomes.
Study Design: Retrospective observational study.
Methods: We identified 132 414 patients in a large healthcare program who were included in 1 or more HEDIS persistent asthma cohorts between 1999 and 2002 and who had continuous insurance and pharmacy benefit coverage for the entire 4-year observation period. Medication, emergency department, and hospital use in 2002 was identified using electronic claims and pharmacy information.
Results: Overall, 47.9% of the patients were identified as having persistent asthma in only 1 of 4 years, 40.8% had at least 2 consecutive years, and 28.2% had at least 3 consecutive years. In bivariate and multivariate analyses, more consecutive years of HEDIS persistent asthma qualification significantly increased the likelihood of frequent short-acting β-agonist use, inhaled anti-inflammatory corticosteroid use, at least 1 emergency department visit, and at least 1 hospitalization. The strongest relationship was for 3 or more consecutive years of HEDIS qualification.
Conclusions: A significant portion of the HEDIS persistent asthma cohort does not qualify on a year-to-year basis, suggesting that the current 1-year qualification period or the underlying administrative case definition for persistent asthma may be suboptimal. Further clinical validation studies are needed to determine the optimal criteria for a more useful HEDIS persistent asthma case definition.
(Am J Manag Care. 2005;11:650-654)
Asthma is a chronic inflammatory lung disease.1
There is no gold standard test for the diagnosis of
asthma. It is typically based on clinical symptoms
and is ideally confirmed by the demonstration of
reversible airway obstruction or bronchial hyperreactivity.2 Clinical audits of asthma diagnoses have consistently
demonstrated significant underdiagnosis and
overdiagnosis.3-6 The ability of administrative data systems
of most health plans to identify the diagnosis of
asthma is still unknown.
The current Health Plan Employer Data and
Information Set (HEDIS) measure for asthma uses administrative
data collected during 1 year to identify
patients with presumed persistent asthma and evaluates
controller therapy during the next year. It has been
reported that this asthma case identification using
administrative data in children cannot distinguish persistent
asthma from transient wheezing syndromes.7 It
is also difficult to determine asthma severity using
One of the historical limitations of administrative
data from a single treatment center or healthcare network
is migration of patients into and out of the healthcare
plan.9 Kaiser Permanente Health Care Program
cares for a large group of patients year after year and
can provide multiyear data to evaluate asthma prevalence
and persistence. Vollmer and coworkers,10 in the
Kaiser Permanente Northwest Region, recently published
an article on asthma prevalence using multiple
clinical information systems. They found that asthma
case identification based on 1 year of pharmacy data
would capture only 61% of the prevalent asthma cases
and that the electronic health record alone would identify
only 66% of the total asthma cases.
Despite the clinical limitations of administrative data
to define persistent asthma, such data are available to
most health plans and are potentially useful from a quality
of care perspective. Identifying poor performance on
the HEDIS measure for asthma can be used to target
quality improvement and outreach efforts.
Because few reliable and valid assessment tools exist
to diagnose persistent asthma, further efforts are needed
to improve administrative methods to define persistent
asthma. A limitation of the current HEDIS asthma
inclusion criteria is the inclusion of a significant portion
of patients with intermittent asthma, based on a 2-year
analysis.11 As a result, it will be important to develop
more robust administrative measures so that chronic
treatment can be directed to those who will benefit from
it and so that health plans that provide the best care are
With this background in mind, the present study has
the following 2 general objectives: (1) to evaluate the
occurrence of persistent asthma on a year-to-year basis
as defined by the current HEDIS measure for asthma
and (2) to explore whether alteration of the administrative
definition of persistent asthma results in the identification
of a population that uses more asthma-related
healthcare, including medication use and resource utilization,
which are likely markers of persistent asthma.
We identified 132 414 patients with persistent asthma
aged 5 to 56 years who qualified in at least 1 of 4
HEDIS persistent asthma cohorts identified from 1999
through 2002. The sample was drawn from patients
receiving care from Kaiser Permanente Health Care
Program, a large vertically integrated staff-model
healthcare system. Computerized data from patients
with persistent asthma were drawn from the following
4 geographic regions: northern California, southern
California, Colorado, and the Pacific Northwest (northwest
Oregon and southwest Washington).
Patients were selected based on 3 inclusion criteria.
First, patients had to meet 1 or more of the following
current HEDIS criteria for persistent asthma case
identification during at least 1 of the years observed:
(1) at least 4 asthma medication-dispensing events,
(2) at least 2 asthma medication-dispensing events
and 4 asthma-related outpatient visits, (3) at least 1
asthma-related hospitalization, or (4) at least 1 asthma-related emergency department (ED) visit. Second,
patients were required to maintain continuous insurance
and pharmacy benefit coverage during the entire
study period (January 1, 1999, through December 31,
2002). Third, patients had to stay within the HEDIS-eligible
age range of 5 to 56 years for the entire duration
of the study. If patients aged out during the 4-year
observation period, they were excluded from the study
Primary Independent Variable of the Number of
Years of HEDIS Qualification
The number of years of HEDIS qualification was the
primary independent variable. This variable was categorized
into the following 6 mutually exclusive groups: 1
year only, 2 nonconsecutive years, 2 consecutive years,
3 nonconsecutive years, 3 consecutive years, and 4
Outcome Measures of Medication Use
and Resource Utilization
Medication and resource utilization data were evaluated
during 2002. Data on the use of weighted canister
equivalents of inhaled anti-inflammatory corticosteroids
and short-acting β-agonists were collected from
electronic pharmacy databases. The calculation of
weighted canister equivalents was based on drug potency
and doses per canister (available from the author).
Resource utilization included 1 or more asthma-related
ED visits and hospitalizations during 2002. Both measures
were collected from electronic databases.
All analyses were conducted using the Statistical
Package for the Social Sciences (SPSS version 11.1;
SPSS Inc, Chicago, Ill). Descriptive statistics were calculated
overall and stratified by pediatric and adult populations
for demographic variables, number of years of
HEDIS qualification, medication use, and resource utilization.
We then examined the method of entry into
the HEDIS persistent asthma cohort by the number of
years of HEDIS qualification. Next, we examined the
bivariate association of consecutive years of HEDIS
qualification with medication and resource utilization,
using the c2 test. Finally, logistic regression models were
constructed to examine the independent association of
the number of consecutive years of HEDIS qualification
with medication and resource utilization, adjusting for
age, sex, and geographic region.
A total of 216 025 patients had membership in at
least 1 HEDIS persistent asthma cohort between 1999
and 2002. Of those, 146 531 (67.8%) maintained continuous
insurance and pharmacy benefit coverage for
the entire 4-year observation period (data not shown).
There were 132 414 patients (90.4%) with continuous
insurance and pharmacy benefit coverage who
remained within the HEDIS-eligible age range for the
entire observation period. The total health plan population
within the age cutoffs with continuous insurance
and pharmacy benefit coverage was 2 224 804 patients.
The HEDIS-defined patients with persistent asthma
thus accounted for 6.0% of the health plan population.
Overall, the study population included slightly more
females (55.0%), with less female representation in the
pediatric population and greater female representation
in the adult population (Table 1). About half of the
study population qualified during only 1 of the 4 years
observed, slightly more for the pediatric population
and 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 more
years of HEDIS qualification compared with children.
Within the pediatric population, most patients
entered the HEDIS persistent asthma cohort each year
through medication use alone (range, 71.3%-79.9%) or
through medication use in combination with 1 or more
of the other entry criteria (range, 91.9%-94.3%). A
slightly higher proportion of the adult population qualified
through medication use alone (range, 78.7%-85.5%), while a similar proportion qualified by
medication use in combination with other entry criteria
The number of consecutive years of HEDIS qualification
was strongly associated with medication use in
bivariate analysis (Table 2) and in multivariate analysis
(Table 3) for the pediatric and adult populations. In
both populations, those with 2 or more consecutive
years of HEDIS qualification were more likely to use 1
or more canister equivalents of inhaled anti-inflammatory
corticosteroids and to overuse short-acting
β-agonists (≥ 14 canister equivalents). As might be expected,
in the multivariate comparison, those with 4
consecutive years of HEDIS qualification were the
most likely to use inhaled anti-inflammatory corticosteroids
and to overuse short-acting β-agonists, with
those with only 1 year of HEDIS qualification as the referent
group (Table 3).
The number of years of HEDIS qualification was significantly
associated with resource utilization, although
this association was not as strong as that found for medication
use (Tables 2 and 3). For the pediatric and adult
populations, those with 3 or more consecutive years of
HEDIS qualification were significantly more likely to
have asthma-related ED visits and hospitalizations compared
with those with 1 year of HEDIS qualification
(Table 3). Utilization of asthma-related ED visits and
hospitalizations did not differ for those with 2 consecutive
years of qualification compared with those with
only 1 year of qualification.
This study found that the current 1-year HEDIS qualification
period does not consistently capture the persistent
asthma cohort on a year-to-year basis. About
half of children and adults qualified for the persistent
asthma cohort for only 1 of the 4 years observed.
However, our results suggest that the manner in which
patients entered the HEDIS persistent asthma cohort
does not vary over time, with most children and adults
entering through the use of asthma medications.