Racial-Ethnic Differences in Childhood Asthma Treatment

Eric M. Sarpong and G. Edward Miller

AHRQ Conference September 20, 2011

Introduction

Asthma – chronic, complex and costly health condition – Estimated costs of asthma in the U.S. - $19.7 billion (NHLBI, 2007)

Why childhood asthma medication use?– Recent significant increases in:

Treated prevalence Health care and prescribed asthma drug expenditures (Miller &

Sarpong)– Recent changes in asthma care

Treatment guidelines (NAEPP-EPR3, 2007) - Inhaled corticosteroid (ICS); preferred first-line therapy for persistent asthma

– Changes in use and availability of new pharmacotherapies Increased use of controller medications Decreased use of mono-therapy with relievers

Differences in asthma treatment persists

Pharmaceutical Treatment of Asthma

Recommended treatment depends on asthma severity (NAEPP-EPR3, 2007)

– Controllers (e.g., inhaled corticosteroid) Used in managing asthma symptoms, by

minimizing inflammation and reducing the risk of serious exacerbations

Recommended for all children with persistent asthma

– Relievers (e.g., inhaled short acting beta agonists) Used in managing moderate or severe asthma

attacks by promptly relaxing airway muscles Recommended for all children with intermittent

asthma

Treated Prevalence of Childhood Asthma by Race-Ethnicity, 2005-2008

Source: MEPS, 2005-2008. Estimates for insured children with reported treatment for asthma. Differences from NH Whites significant at p < .05.

All Children NH White NH Black Hispanic0

1

2

3

4

5

6

7

8

9

10

6.47846.2377

8.692

5.834

Per

cent

Use of Controllers Among Children With Treatment for Asthma, 2005-2008

Source: MEPS, 2005-2008. Estimates for insured children with reported treatment for asthma. Differences from NH Whites significant at p < .05.

All Children NH White NH Black Hispanic0

10

20

30

40

50

60

70

80

59.4502

68.6287

44.1524

49.5186

Per

cent

Use of Relievers Only , Among Children with Treatment for Asthma, 2005-2008

Source: MEPS, 2005-2008. Estimates for insured children with reported treatment for asthma. Differences from NH Whites significant at p < .05.

All Children NH White NH Black Hispanic0

5

10

15

20

25

30

35

40

45

30.45

22.9275

42.7624000000001

38.6789

Per

cent

Differences in Treated Prevalence and Use of Asthma Medications

NH Black children - more likely than NH White and Hispanic children to be treated for asthma

NH Black and Hispanic children - less likely than NH White children to use controllers

NH Black and Hispanic children - more likely than NH White children to use relievers only

Previous Research

Large body of literature with mixed evidence on differences in children’s use of asthma medication

Some studies find no differences by race-ethnicity, others do find a difference

Studies differ on a number of dimensions– Time period– Population (e.g., Medicaid, private claims, nationally

representative)– Degree to which they control for differences in underlying

characteristics across groups

Research Objective and Contribution

Research Objective – Examine differential use of asthma medication by race-

ethnicity– Examine extent to which differences in mean predisposing,

enabling and need characteristics explain differences in use

New Contribution – Previous literature limited - Medicaid data, administrative

data or community samples, key variables unavailable– Comprehensive look at differences using nationally

representative data (MEPS)– Provide descriptive information on reasons for differences

and possible approaches to addressing these differences

Analytic Approach

Describe differences in controllers and relievers only use by race-ethnicity

Estimate pooled regression models with binary outcomes (i.e., controllers and relievers only)– Explanatory variables

Predisposing (e.g., socio-demographics, geographic) Enabling (e.g., health insurance, family income/structure

and parental education/employment status) Need (e.g., health status, co-occurring conditions)

Use Oaxaca-Blinder method - decompose differences into:– Explained - differences due to mean differences in

explanatory variables– Unexplained - differences due to differences in

estimated coefficients

Data

Data– 2005-2008 Medical Expenditure Panel Survey (MEPS)

Population studied– Insured children (ages 0-17) with reported treatment for

asthma Treatment = health service use associated with asthma

– Sample size N = 813 NH White children N = 608 NH Black children N = 644 Hispanic children

Drugs – Link MEPS drug data by NDC to the Multum Lexicon– Use generic names to categorize drugs as controllers or

relievers– Measures: any use of controllers and relievers only

Descriptive Results - Differences in Mean Characteristics

NH Black children more likely than NH White children to– Be covered by public insurance, live in an MSA and in the south

(predisposing)– Live in families with low levels of family income, low parental

education, unmarried parent and unemployed parent (enabling)– Be in fair/poor physical health (need)

Hispanic children more likely than NH White children to– Be covered by public insurance, live in an MSA, in the west, have

non-native parents and parents with risky attitudes towards health (predisposing)

– Live in families with low levels of family income, low parental education, unmarried parent, unemployed parent and live in a larger family (enabling)

– Be in fair/poor physical health (need)

Multivariate Results - Predictors of Controller and Reliever Only Use

Positive effects on controller use– Age 5-11, native parents, married parent, fair/poor physical

health, and having treatment for allergies

Negative effects on controller use– Female, MSA, western region, low family income, parental

education, and large family

Positive effects on reliever only use– Female, MSA, western region, native parents, low family

income, and large family

Negative effects on reliever only use– Age 5-11, married parent, fair/poor physical health, and

having treatment for allergies

Results are based on coefficient estimates from pooled linear probability models.

Oaxaca-Blinder Decomposition - NH Whites vs. NH Blacks, Controllers

Important variablesEnabling Low income ≤ High school Family of > 4 Unmarried

Source: MEPS, 2005-2008. Estimates for insured children with reported treatment for asthma. Differences from NH Whites, significant at p < .10.

Total Difference in Controller Use = 24.5%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Unexplained; 12.8

Need; 2.2

Enabling; 8.6

Per

cent

con

trib

utio

n to

gap

in u

se Explained

Oaxaca-Blinder Decomposition Results - NH Whites vs. NH Blacks, Relievers Only

Important variablesEnabling Low income Family of > 4 Unmarried

Source: MEPS, 2005-2008. Estimates for insured children with reported treatment for asthma. Differences from NH Whites, significant at p < .10.

Total Difference in Reliever Only Use = 19.8%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Unexplained; 12.2

Need; 1.6

Enabling; 5.7

Per

cent

con

trib

utio

n to

gap

in u

se Explained

Oaxaca-Blinder Decomposition Results - NH Whites vs. Hispanics, Controllers

Important variablesPredisposing MSA West Non-native parentsEnabling Low income ≤ High school Family of > 4 Unmarried

Source: MEPS, 2005-2008. Estimates for insured children with reported treatment for asthma. Differences from NH Whites, significant at p < .10.

Total Difference in Controller Use = 19.1%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Unexplained; 4.4

Need; 1.7

Enabling ; 6.3

Predisposing; 6.6

Per

cent

con

trib

utio

n to

gap

in u

se Explained

Oaxaca-Blinder Decomposition Results - NH Whites vs. Hispanics, Relievers only

Important variablesEnabling Low income ≤ High school Family of > 4 Unmarried

Source: MEPS, 2005-2008. Estimates for insured children with reported treatment for asthma. Differences from NH Whites, significant at p < .10.

Total Difference in Reliever Only Use = 15.8%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Unexplained; 7.8

Need; 1.2

Enabling ; 4.4

Per

cent

con

trib

utio

n to

gap

in u

se Explained

Interpretation of Oaxaca-Blinder Decomposition Results

Several characteristics in the domains of the behavioral model were associated with – Controller use – Reliever only use

Our model– Explained most differences in:

Controller use for NH Blacks and Hispanics Reliever only use for Hispanics

– Differences in reliever only use for NH Blacks, largely unexplained

Unobservable factors - differences in responses to characteristics, may be important

Limitations and Future Research

Limitations– No measure of asthma severity

Results may change if severity differs across groups

– Non-causal descriptive model Future research

– Depart from linear probability models– Use non-parametric approach

Raking (Pylypchuk and Selden, 2008, JHE)– Follow previous approaches

Kirby et al, 2010 MCRR and Hudson et al, 2007

Conclusions

Non-Hispanic whites: low asthma treated prevalence and reliever only use and, higher controller use

Enabling factors explained some, not all, of the differences in controller and reliever only use for NH Blacks and Hispanics

Predisposing factors explained some of the differences in controller use for Hispanics

Some unobservable characteristics may have also played a role

Results are consistent with studies in other therapeutic classes of drugs and disease areas

References

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Shields A, Comstock C, Weiss KB. (2004). Variations in asthma care by race/ethnicity among children enrolled in a state Medicaid program. Pediatrics,113:496 –504.

Finkelstein JA, Lozano P, Farber HJ, et al. (2002). Underuse of controller medications among Medicaid-insured children with asthma. Arch Pediatr Adolesc Med,56(6):562-7.

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Blinder, A. (1973). Wage discrimination: Reduced form and structural estimates. Journal of Human Resources, 8, 436-455.

Oaxaca, R. L. (1973). Male-female wage differentials in urban labor markets. International Economic Review, 14, 693-709.