1. Measuring Asthma Prevalence and Severity in Children Lara Akinbami, MD Infant and Child Health Studies Branch National Center for Health Statistics

2. Overview  National trends in childhood asthma prevalence, hospitalization and mortality, 1980 to 2000  Racial disparities in asthma prevalence, hospitalization and mortality

3. NCHS systems with asthma data  Prevalence  National Health Interview Survey (NHIS): household survey  Hospitalizations  National Hospital Discharge Survey (NHDS): record abstraction  Mortality  National Vital Statistics System (NVSS): death certificate data

4. Asthma prevalence

5. Asthma prevalence, 1980-96, lifetime diagnosis & asthma attack prevalence, 1997-2000, NHIS Asthma prevalence (4.3% per yr  ) Asthma lifetime diagnosis Asthma attack prevalence

6. National Health Interview Survey 1997 redesign  Purpose of the redesign  Improve data quality  Simplify the survey  Reduce the questionnaire length  The redesign involved  Survey restructuring  Changes in NHIS core questions

7. 1980-1996 NHIS core Redesigned (1997-2000) NHIS core Screener question: (None)Has a doctor or other health professional ever told you that your child had asthma? Past 12 months question: During the past 12 m, did anyone in the family have asthma? IF YES: During the past 12 m, has your child had an episode of asthma or an asthma attack?

8. Asthma prevalence, 1980-96, lifetime diagnosis & asthma attack prevalence, 1997-2000, NHIS Asthma prevalence (4.3% per yr  ) Asthma lifetime diagnosis Asthma attack prevalence

9. Measuring the 1997 redesign impact: NHIS Child Health Supplement  NHIS includes periodic supplements on selected health topics: 1981 and 1988 Child Health Supplement  In-depth survey of child health  Asthma questions included

10. 1980-1996 NHIS core Redesigned (1997-2000) NHIS core NHIS Child Health Supplement (1981, 1988) Screener question: (None)Has a doctor or other health professional ever told you that your child had asthma? Did your child ever have asthma? Past 12 months question: During the past 12 m, did anyone in the family have asthma? IF YES: During the past 12 m, has your child had an episode of asthma or an asthma attack? IF YES: Did your child have asthma in the past 12 m?

11. 1981 and 1988 Core and Child Health Supplement (CHS) asthma prevalence estimates 19811988 Core question 3.8%5.1% CHS questions 3.2%4.3% % difference18.218.6

12. Asthma prevalence (1980-96), and modified asthma attack prevalence (1997-2000), NHIS Asthma prevalence Asthma attack prevalence High and low modified estimates

13. Summary: NHIS redesign impact on prevalence estimates  Most of the apparent decrease in 1997 resulted from the redesign  If the survey was not changed, 1997- 2000 estimates would have been ~ 20% higher  This is likely an underestimate of the impact of the redesign

14. 2001 NHIS: additional asthma question  “Does your child STILL have asthma?”  Will provide an estimate of current asthma prevalence  Estimate still won’t be directly comparable to pre-1997 estimates

15. Asthma hospitalizations

16. Childhood asthma hospitalizations  Asthma hospitalization can be used as an indicator of severity  However, asthma is a condition sensitive to access to high quality ambulatory health care  Hospitalization data measures events rather than persons

17. Asthma hospitalizations for children 0-17 years, 1980-2000 NHDS 1.4% per year increase

18. Asthma mortality

19. Childhood asthma mortality  Rare event  But, avoidable  Also affected by factors in addition to prevalence and severity  Health care utilization  Patient education and “compliance”

20. Asthma deaths, children 0-17 years, 1980-2000, NVSS 3.4% per year increase ICD-9ICD-10

21. Asthma deaths, children 0-17 years, 1980-2000, NVSS 3.4% per year increase ICD-9ICD-10

22. Summary of trends in childhood asthma  Increasing burden of childhood asthma from 1980 to the mid 1990s  Recent plateau in asthma attack prevalence, hospitalizations and deaths  Complications: NHIS redesign, ICD code change

23. Racial disparities in asthma

24.  Widespread perception: minorities have much higher asthma prevalence  Minorities also at higher risk for poor outcomes  Impact of socioeconomic status on disparities

25. Racial disparities: asthma prevalence, hospitalization, and mortality Attack prevalence (1998) Per 100 Hospitalization (1998-99) Per 10,000 Mortality (1997-98) Per 1,000,000 Non-Hispanic White 5.215.52.2 Non-Hispanic Black 6.856.910.1 Rate Ratio (black/white) 1.33.74.6

26. Racial and income disparities in asthma: NHIS  Race and income data available  NHIS contains prevalence and morbidity data  Survey years 1993-1996 grouped for adequate sample size  Children  3 years excluded due to diagnostic uncertainty

27. Average annual asthma prevalence, 1993-1996, children 3-17 years

28. Activity limitation due to asthma, 1993- 1996, children 3-17 years with asthma

29. Racial disparities in health care use  NHIS has information about Health care use: asthma doctor visits Severity: asthma bed days  Use disability ratio  Adjust health care use for severity of illness  The higher the ratio, the more health care utilized per unit of severity

30. Doctor contacts & bed days due to asthma in the past 2 weeks, children 3-17 years Doctor contacts (mean) Bed days (mean) Ratio: Doctor contacts per bed days Black poor 0.080.610.13 Black nonpoor 0.060.240.26 White poor 0.110.480.22 White nonpoor 0.090.210.42

31. Summary of racial disparities in asthma  Disparities in asthma morbidity and mortality > prevalence disparities  Black poor children underuse ambulatory care given their greater morbidity  It is not likely that disparities in prevalence drive the very large disparities in asthma hospitalizations and mortality

32. Overall summary of childhood asthma  Dramatic increase in the asthma burden among children until mid-1990s  Recent plateau in asthma attack prevalence, hospitalizations, and mortality  Minority and poor children face:  Only slightly higher risk of having asthma  Much higher risk of morbidity  Inappropriately low use of ambulatory care  Much higher risk of mortality

33. Acknowledgements National Center for Health Statistics, CDC: Ken Schoendorf, MD, MPH Jennifer Parker, PhD Julia Rhodes, PhD Vanderbilt University: Bonnie LaFleur, PhD National Center for Environmental Health, CDC Jeanne Moorman, PhD