# Presentation: 457005

## Immunization Registry and Provider-Reported Vaccination Histories:Assessing Missing Vaccinations

- Linda Piccinino (Abt Associates, Inc.),
- Meena Khare (C.D.C.),
- Mike Battaglia (Abt Associates, Inc.),
- Diana Bartlett (C.D.C.),
- Lawrence Barker (C.D.C.)
- Centers for Disease Control and Prevention
- 38th National Immunization Conference
- Abt Associates, Inc.

## N.I.S. Registry Data Query Study

- Study integrated registry query consent question into standard National Immunization Survey (N.I.S.) interview
- Four mature registry sites participated in the study
- Each site had one quarter of data collection (one site in quarter 3 2002, three sites in quarter 4 2002)
- Vaccination history data obtained from N.I.S. provider reports and from state/local registries for children with parental consent

## Research Problem

- Need a way to assess the quality of vaccination data for N.I.S. children with data available from both N.I.S. provider reports and immunization registries

## Objectives of this Analysis

- To compare vaccination histories obtained from immunization providers and registries for a sample of N.I.S. children 19 to 35 months old
- To examine the pattern of missing vaccination data by vaccination type, dose and source of data
- To help identify subgroups of children where immunization data were more likely to be absent, by characteristics associated with the children and their provider types

## Analysis Groups

- Sample consisted of N.I.S. children with *both* registry and provider data
- Data were combined for four sites because of sample size and confidentiality concerns
- For each vaccine type, children were grouped into two subgroups of children with:
- provider-reported data but had some missing registry data
- registry-reported data but had some missing provider data

## Methodology for Identifying Missing Vaccinations

- 323 children with registry vaccination data (at least one shot) and adequate provider data in the N.I.S.
- Focus on D.T.a.P. vaccinations present in one source but missing from the other source
- Children U.T.D. with 4 doses of D.T.a.P. in the provider data (N equals 245) but fewer than 4 doses in the registry data (N equals 75)
- Children U.T.D. with 4 doses of D.T.a.P. in the registry data (N equals180) but fewer than 4 doses in the provider data (N equals 16)
- Determine dose number (order) of missing vaccination

## Determining the Dose Number of Missing Vaccinations

- Provider data:
- February 15, 2001
- August 12, 2001
- January 14, 2002
- September 3, 2002
- Registry data:
- February 15, 2001
- January 16, 2002
- August 30, 2002
- For each registry vaccination date, determined which provider vaccination date was closest in time
- Dose 1
**Missing**
- Dose 3
- Dose 4

## Children with Missing D.T.a.P. Doses

- Registry: 75 Children (30.6 percent)             Provider: 16 Children (8.9 percent)
- Chart follows: Columns 1-4 titled: Number of missing D.T.a.P. doses of vaccinations in child vaccination record
- Row 1: Missing, Missing, Missing, Missing, Registry: 10.7 percent and Provider: none.Row 2: Missing, Missing, Missing, Dose 4, Registry: 8.0 percent and Provider: 6.3 percent.Row 3: Missing, Missing, Dose 3, Dose 4, Registry: 9.3 percent and Provider 12.5 percent.Row 4: Missing, Dose 2, Missing, Missing, Registry 2.7 percent and Provider: none.Row 5: Missing, Dose 2, Dose 3, Missing, Registry: 1.3 percent and Provider: none.Row 6: Missing, Dose 2, Dose 3, Dose 4, Registry 6.7 percent and Provider: none.
- Row 7: Dose 1, Missing, Missing, Missing, Registry 6.7 percent and Provider: 6.3 percent.
- Row 8: Dose 1, Missing, Missing, Dose 4, Registry 6.7 percent and Provider: none.
- Row 9: Dose 1, Missing, Dose 3, Missing, Registry 5.3 percent and Provider: none.
- Row 10: Dose 1, Missing, Missing, Dose 4, Registry 6.7 percent and Provider: 18.7 percent.
- Row 11: Dose 1, Dose 2, Missing, Missing, Registry 6.7 percent and Provider: 6.3 percent.
- Row 12: Dose 1, Dose 2, Missing, Dose 4, Registry 8.0 percent and Provider: none.
- Row 13: Dose 1, Dose 2, Dose 3, Missing, Registry 21.3 percent and Provider: 50.0 percent.
- Total registry is 100 percent. Total Provider is 100 percent.

## Summary of Missing Doses:  Dose Order

- Chart:
- Row 1: Order of Missing Doses: first dose missing, Registry: 38.7 percent and Provider: 18.8 percent
- Row 2: Order of Missing Doses: second dose missing, Registry: 53.4 percent and Provider: 43.8 percent
- Row 3: Order of Missing Doses: third dose missing, Registry: 49.5 percent and Provider: 18.9 percent
- Row 4: Order of Missing Doses: fourth dose missing, Registry: 54.7 percent and Provider: 62.6 percent

## Summary of Missing Doses:  Dose Frequency

- Chart:
- Row 1: Number of Missing Doses: One dose missing, Registry: 42.7 percent and Provider: 68.7 percent
- Row 2: Order of Missing Doses: Two doses missing, Registry: 29.3 percent and Provider: 18.8 percent
- Row 3: Order of Missing Doses: Three doses missing, Registry: 17.4 percent and Provider: 12.6 percent
- Row 4: Order of Missing Doses: Four doses missing, Registry: 10.7 percent and Provider: 0.0 percent

## Reasons for Missing Provider Doses

- 23 children had more registry doses than provider doses when all vaccines were examined – We reviewed the Immunization History Questionnaires (I.H.Q.) and recontacted the providers when necessary. Extra registry vaccination dose was:
- very close to another registry vaccination dose date
- the 4th dose omitted from the I.H.Q.; or that dose was administered by a provider who did not respond to the N.I.S.
- not** **the last dose and was inadvertently omitted when the I.H.Q. was filled out
- for a child with multiple providers but household respondent only identified one provider
- for a child for whom not all identified providers responded or returned the I.H.Q. with vaccination data

## Characteristics of Children with Missing D.T.a.P. Doses

- Row 1: Shot card used during N.I.S. interview
- Children with Missing Registry Doses (n equals 75): 68.0 percent
- Children with Missing Provider Doses (n equals 16): 31.2 percent
- Row 2: Child only has private provider or providers
- Children with Missing Registry Doses (n equals 75): 68.0 percent
- Children with Missing Provider Doses (n equals 16): 62.5 percent
- Row 3: Child has 2 or more providers
- Children with Missing Registry Doses (n equals 75): 38.7 percent
- Children with Missing Provider Doses (n equals 16): 43.7 percent
- Row 4: Child’s provider reported vaccinations to registry
- Children with Missing Registry Doses (n equals 75): 65.3 percent
- Children with Missing Provider Doses (n equals 16): 68.8 percent

## Implications for Data Quality

- Incomplete Vaccination Histories
- The vaccination histories were not always complete.
- For children with 4 *provider* doses of D.T.a.P., about 31 percent of children had one or more doses missing in the registry data.
- For children with 4 *registry* doses of D.T.a.P., only about 9 percent of children had one or more doses missing from the provider reports.
- 	*These suggest that registry histories tended to be more incomplete than provider histories.*

## Implications for Data Quality

- Mixed Pattern of Missing Data
- The frequency and order of the missing doses for D.T.a.P. varied by source of data.
- 	*Therefore, source of data should be considered when interpreting results and making estimates.*
- The fourth D.T.a.P. dose was the most likely to be missing in both the provider and registry data, although the reasons this 4th dose was missing might differ by data source.

## Implications for Data Quality

- Special Subgroup Issues
- Children with multiple providers were more likely to have missing provider doses
- Children with only private providers were more likely to have missing registry doses
- Providers that were not identified by respondents might also be responsible for some of the missing data
- A higher percentage of children with missing registry data had shot card data than for children with missing provider data

## Conclusion

- Results may not be conclusive due to the small sample size.
- Results showed a mixed pattern of missing doses.
- Data quality concerns suggest that building combined “best value” estimates may be difficult since the quality and completeness of registry data are lacking.
- Although there are data quality problems, some registries were more complete than others.
- Results strongly support further research on supplementing provider-reported immunization histories with registry data in order to improve vaccination coverage estimates.

## Next Step

- Future research plans include looking at the quality of registry data compared to household-reported vaccination data from shot cards