The American Journal of Managed Care July 2008
Identifying High-risk Asthma With Utilization Data: A Revised HEDIS Definition
Objective: To develop a definition of high-risk asthma that more precisely identifies patients needing case management than the 2006 Healthcare Effectiveness Data and Information Set (HEDIS) definition.
Study Design: Two-year claims-based study, with cross-sectional phone survey data, for a sample of 769 youths (age 11-17 years) with asthma.
Methods: The 2006 HEDIS measure defines high-risk asthma as meeting any of the following criteria: =1 emergency department (ED) visits, =1 hospitalizations for asthma, =4 asthma medication prescriptions, or =4 ambulatory visits for asthma with =2 prescriptions for asthma medication in 1 year. We created a revised definition =1 ED visits or =1 hospitalizations for asthma or =1 oral steroid prescriptions for asthma) and identified patients with high-risk asthma in year 1 according to each definition. We compared the 2 groups on demographic and clinical characteristics, and healthcare utilization and costs in years 1 and 2.
Results: The revised definition identified 29% of the sample as having high-risk asthma, whereas the 2006 definition identified 67%. Compared with the 2006 definition, the revised definition identified patients with significantly greater asthma-related physical health problems and higher medical costs in year 1. In year 2, youths classified as high risk by the revised definition made more ED visits and were more likely to use oral steroids than those classified as high risk by the 2006 definition. Conclusion: The revised high-risk asthma definition identifies half as many individuals and is better able to identify patients with poorly controlled asthma in the subsequent year.
(Am J Manag Care. 2008;14(7):450-456)
This study developed and tested a definition of high-risk asthma based on a single year of patient utilization data that, compared with the 2006 HEDIS definition, more precisely identified patients needing case management.
The 2006 HEDIS definition categorized 67% of youths with asthma as high risk, whereas the revised definition categorized just 29% of youths as high risk.
Compared with the 2006 HEDIS definition, the revised definition identified youths with significantly greater asthma-related physical health problems and higher medical costs in the first year, and youths who made more emergency department visits and were more likely to use oral steroids in the second year.
The HEDIS definition of high-risk asthma was amended in 2007 to reduce the amount of misclassification. The 2007 definition requires patients to meet at least 1 of the utilization criteria in a 12-month period for 2 consecutive 12-month periods and the criteria met in each period do not need to be the same ones. Although the extended time period increases the fidelity of the HEDIS definition, the 24-month period limits the definition’s utility as a case-finding tool. A definition of high-risk asthma that requires only 12 months of utilization data, instead of 24 months, would enable health plans to identify patients needing disease management in a time frame that would be amenable to preventive interventions.
In this article we describe development of a revised definition that identifies patients with asthma who are at risk for adverse outcomes, using 12 months of utilization data. The revised definition we proposed is similar to the 2006 definition in that only 12 months of utilization data are required, but the criteria are different. We removed 2 above-mentioned criteria (“4 or more prescriptions for asthma medication” and “4 or more ambulatory visits for asthma plus 2 or more prescriptions for asthma medication”), hypothesizing that youths who met only these criteria were not as a group at high risk for adverse outcomes. The criterion of 1 or more oral steroid prescriptions for asthma was added to capture youths requiring treatment for significant exacerbations. In this study we tested the revised definition against the 2006 HEDIS definition to determine whether one is more suitable than the other for identifying high-risk patients. Compared with the 2006 HEDIS definition, we hypothesized the revised definition would capture fewer of the youths with well-controlled persistent asthma and fewer of the youths with intermittent asthma.
The data for this study were collected as part of the Stress and Asthma Research (STAR) study, a cross-sectional survey study of depression and anxiety among youths with asthma.13 Potential subjects for the STAR study were youths (age 11-17 years) with asthma who were enrolled in a Group Health Cooperative (GHC) insurance plan for at least 6 months. GHC is a nonprofit HMO with 25 primary care clinics in Washington State owned by GHC as well as 75 contracted clinics. Youths with asthma were identified through the GHC automated cost and utilization database system by at least 1 of the following types of utilization:
• At least 1 hospitalization in the past year with an asthma diagnosis and at least 1 asthma prescription during that year.
• At least 1 emergency department (ED) or urgent care visit in the past year with an asthma diagnosis and at least 1 asthma prescription during that year.
• At least 2 office visits in the past year with an asthma diagnosis and at least 1 asthma prescription during that year.
• At least 1 visit in the past year with an asthma diagnosis and another in the past 18 months, and at least 1 asthma prescription.
• Only 1 asthma visit in the past year but at least 2 asthma prescriptions filled on different days in that year.
• At least 4 prescriptions for asthma medication in the past year.
These criteria were developed to identify youths with active asthma and screen out patients with very mild asthma (such as mild exercise-induced asthma) and youths with spurious asthma diagnoses (ie, wheezing secondary to acute respiratory infection). All youths meeting inclusion criteria were invited to participate in the STAR study. Participants in the STAR study with cost and utilization data were included in this analysis. All participants gave informed consent. The study protocols were reviewed and approved by the institutional review board of GHC.
Following receipt of a letter inviting participation in the STAR study, subjects were screened by telephone interview, which included a 10- to 15-minute parent interview and a 45- to 75-minute youth interview. The parent interview included confirmation that their child had been diagnosed with asthma, the number of years since diagnosis with asthma, and demographic questions.
Demographic Information. Child age and sex were determined from administrative data and confirmed during parent interview. The family’s address and zip code were linked to census data to determine the median household income of their census block group. Enrollment in Medicaid or the Washington State Basic Health Plan was identified through administrative data.
Asthma Experience and Health Status Indicators. Asthma symptom days, or the number of days with asthma symptoms in the prior 2 weeks, was used as a proxy for asthma severity.14 Based on the National Asthma Education and Prevention Program guidelines, 0 to 4 symptom days is considered to be equivalent to intermittent to mild persistent asthma and 5 to 14 symptom days is considered persistent asthma.15 The youth’s experience with asthma was identified in the phone interview using the Child Health Survey–Asthma (CHS-A). The CHS-A is a functional status measure with high reliability and validity in capturing a broad range of asthma experiences. Three of the instrument subscales are included in this analysis (physical health, activity limitations, and emotional health), which are scored from 0 to 100, with higher scores indicating better outcomes.16 The Pediatric Chronic Disease Score (PCDS) is an algorithm drawing on claims data for prescription fills that classifies children into chronic disease categories.17 The modified version of the PCDS used in the STAR study did not include medications used primarily for asthma, anxiety, or depression. Higher scores on the modified PCDS indicate greater non–asthma-related medical morbidity.
Cost and Utilization. Cost and utilization data were taken from the GHC computerized cost and utilization database system for the 12-month period preceding baseline (year 1) and the 12-month period following baseline (year 2). This system uses general ledger costs to calculate actual budget-based cost (not charges) for all services provided or purchased by GHC. Total health services costs include costs for all conditions including asthma.
High-risk status according to the 2006 HEDIS and revised definitions was determined based on individual utilization in year 1 according to the criteria shown in the Figure. We examined the number of youths identified by individual criteria in order to compare the relative contributions of each criterion. Descriptive statistics were used to evaluate the revised definition of high-risk asthma, first by comparing the characteristics of high-risk youths with those of low-risk youths identified by each definition, and second by comparing the characteristics of the high-risk youths identified by each definition.
Differences between the high-risk and low-risk groups within each definition were evaluated by t tests for groups with unequal variance and Pearson χ2 tests. Differences between the high-risk groups identified by each definition also were compared by t tests for groups with unequal variance and Pearson χ2 tests. For all tests a P value of less than .05 was considered significant. The characteristics examined were youth and parent demographics, health characteristics including asthma symptom days, and health service costs and utilization in year 1 and year 2. The analysis was conducted using Stata version 8.0.18
Of the 1458 youths and parents in the initial sample, 170 were ineligible, leaving a sample of 1288. Reasons for ineligibility included the following: child did not have asthma (n = 63), disenrollment from GHC (n = 84), language ineligibility (n = 11), parent too ill (n = 6), and other (n = 6). Of the eligible sample, 833 parents gave consent and permission for the study to contact their child with asthma. From these 833, the study obtained child consent and completed 781 interviews for a final recruitment rate of 60.6%. This analysis was based on a final sample of 769 youths (12 youths or their parents did not give permission for the use of cost and utilization data). Full details about the sample are published elsewhere.19
The demographic and health characteristics of the total sample are described in Table 1. The 2006 HEDIS definition classified 518 youths (67%) as high risk, whereas the revised definition classified only 223 youths (29%) as high risk. All youths classified as high risk by the revised definition also were classified as high risk by the 2006 HEDIS definition.
Criterion and Stepwise Comparison of High-risk Definitions
Table 2 reports the number of youths identified by each individual criterion. The definitions also were examined in a stepwise manner, and the cumulative number of youths identified with each additional criterion are reported for each definition. Nine youths (1.2%) had inpatient hospitalizations, and 65 youths (8.5%) had inpatient hospitalizations or ED visits. The addition of the revised definition criterion “1 or more prescriptions for oral steroids” identified a total of 223 youths (29.0%). In contrast, the addition of the HEDIS criterion “4 or more prescriptions for asthma” identified 514 youths (66.8%), and the fourth HEDIS criterion “4 or more ambulatory visits and 2 or more prescriptions for asthma” captured an additional 4 youths, for a total of 518 (67.4%). The 2006 HEDIS definition identified 295 youths as high risk that the revised definition did not identify; these 295 youths had no asthma-related hospitalizations, ED visits, or prescriptions for oral steroids.