Risk Factors for Under-Immunization in Urban Areas and Rest of the United States, NIS 1999

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Risk Factors for Under-Immunization in Urban
Areas and Rest of the United States, NIS 1999

• Ram B. Jain, Ph. D.
• Ali H. Mokdad, Ph. D.
• Lawrence E. Barker, Ph. D.
• Susan Chu, Ph. D.
• National Immunization Program
• Centers for Disease Control and Prevention

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To determine how risk factors associated with
under-immunization (for 43133 series) differ
in urban areas and rest of the United States.
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• A child is considered to be under-immunized for
  43133 series if the child, by the age of 35
  months, has NOT received at least
• 4 doses of DTP/DTaP, and
• 3 doses of polio, and
• 1 dose of a measles containing vaccine, and
• 3 doses of Hib, and
• 3 doses of hepatitis B

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Urban Areas 28 urban Action Plan Areas as
defined in NIS were combined together Rest of
the United States Remaining 50 Immunization
Action Plan Areas in NIS
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• In published studies conducted primarily in local
  urban populations, several factors have been
  found to affect under-immunization rates such as
• race (e.g., non-Hispanic blacks and Hispanics)
• (Wood et al, 1995 Kenyon et al, 1998
  Orenstein et al 1990)
• socioeconomic status (e.g., low family income)
• (Bates et al, 1994)
• higher birth order
• (Wood et al, 1995)
• others

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• The study conducted by us differs from other
  studies in the following respects
• Uses a logistic model to analyze data so effect
  of correlations between possible risk factors is
  taken into consideration
• A more complete set of risk factors is used in
  the logistic model
• Uses national data so the results are
  generalizable
• Evaluates risk factors in both urban areas and
  rest of the United States

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National Immunization Survey

• Implemented in 1994
• To develop coverage estimates for children
• aged 19-35 months of age
• Quarterly survey (annual estimates possible)
• About 34,000 children sampled every year
• In 78 Immunization Action Plan (IAP) areas
• (DC, 27 urban areas, 50 states)

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Under-Immunization Rates for 1999
Urban Areas 30.5 (95 CI 28.7-32.3) Rest of
U.S.A 25.8 (95CI 24.6-27.0) p lt.01
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Logistic Regression
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Dependent Variable Under-Immunized for
43133 (0,1)
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• National data
• Urban data
• Rest of the United States data

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Adj. OR 95 CI
Rest of the United States Ref.
Urban Areas 1.2 (1.0, 1.3)
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Urban Areas Rest of the United States
Order of Birth OR 95 CI OR 95 CI
First Born Ref. Ref.
Not First Born 1.3 (1.1, 1.7) 1.4 (1.2, 1.6)
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Urban Areas Rest of the United States
Race/Ethnicity OR 95 CI OR 95 CI
Non-Hispanic White Ref. Ref.
Non-Hispanic Black 1.1 (0.9, 1.4) 1.0 (0.9, 1.3)
Hispanics 1.0 (0.8, 1.3) 1.1 (0.9, 1.3)
Non-Hispanic Other 1.0 (0.5, 1.5) 1.2 (0.9, 1.5)
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Urban Areas Rest of the United States
Family Income OR 95 CI OR 95 CI
gt75,000 Ref. Ref.
50,001-75,000 0.8 (0.6, 1.1) 0.9 (0.8, 1.1)
30,001-50,000 1.0 (0.7, 1.4) 1.0 (0.8, 1.2)
lt30,000 1.1 (0.8, 1.5) 0.9 (0.8, 1.2)
Unknown 0.7 (0.7, 1.4) 1.1 (0.8, 1.4)
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Urban Areas Rest of the United States
Inter-State Mobility OR 95 CI OR 95 CI
Not Moved Ref. Ref.
Moved 1.5 (1.1, 2.1) 1.1 (0.9, 1.4)
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Urban Areas Rest of the United States
Mothers Age OR 95 CI OR 95 CI
gt30 Years Ref. Ref.
20-29 Years 1.3 (1.1, 1.5) 1.4 (1.2, 1.6)
lt19 Years 1.6 (1.0, 2.4) 1.1 (0.8, 1.6)
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Urban Areas Rest of the United States
Mothers Education OR 95 CI OR 95 CI
College Degree Ref. Ref.
Some College 1.2 (0.9, 1.6) 1.1 (0.9, 1.3)
High School 1.3 (1.0, 1.6) 1.3 (1.1, 1.5)
lt High School 1.0 (0.9, 1.7) 1.4 (1.1, 1.8)
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Urban Areas Rest of the United States
Mothers Marital Status OR 95 CI OR 95 CI
Married Ref. Ref.
Never Married 1.2 (1.0, 1.5) 1.1 (0.9, 1.4)
Widow/Divorced/Sep. 1.3 (0.9, 1.7) 1.4 (1.1, 1.7)
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Urban Areas Rest of the United States
Number of Providers OR 95 CI OR 95 CI
1 Ref. Ref.
gt1 1.0 (0.8, 1.2) 1.2 (1.1, 1.4)
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Urban Areas Rest of the United States
Provider Type OR 95 CI OR 95 CI
All Public Ref. Ref.
All Hospitals 0.9 (0.6, 1.2) 1.3 (0.9, 1.7)
All Private 0.9 (0.7, 1.1) 1.2 (1.0, 1.4)
All Military/Others 1.1 (0.6, 1.9) 1.5 (1.0, 2.2)
Mixed 0.6 (0.4, 1.0) 0.6 (0.5, 0.8)
Unknown Type 1.3 (1.0, 1.7) 1.5 (1.2, 1.8)
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Urban Areas Rest of the United States
Shot Card Availability OR 95 CI OR 95 CI
Yes Ref. Ref.
No 1.5 (1.2, 1.7) 1.4 (1.2, 1.5)
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Risk Factors Urban vs. Non-Urban Areas
Urban Areas Both Urban areas and Rest of U.S. Rest of United States
Inter-State Relocation Mothers lt19 Years
Later Born Mothers 20-29 Years No Shot Card
Mothers Education - High School or
less Widowed/Separated Mothers Multiple
Providers Hospitals, Military, Private, and
Unknown Providers Mixed Providers (low risk)
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Conclusion Risk factors for under-immunization
are not necessarily same in urban areas and Rest
of the United States
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Recommendation Intervention programs targeted
towards urban areas and rest of the United States
should consider the risk factors that
specifically affect risk of under-immunization in
these areas
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• Future Activities
• Better interpretation of data
• Formulate recommendations to reduce
  under-immunization rates