Registry Data and the National Immunization Survey

Lawrence BarkerNational Immunization Program

Centers for Disease Control and Prevention

Linda Piccinino, Mike BattagliaAbt Associates

Overview

• Description of National Immunization Survey (NIS)

• Comparison of NIS and Registry Data• Findings

– NIS data can be used to track progress toward the HP2010 registry goals (NIS shows that registry data are good but can stand improvement)

– Registry data can be used to benefit NIS (registries contain some vaccines not reported to NIS)

National Immunization Survey

• The NIS is the nation’s primary tool for assessing immunization coverage among 19-35 month old children

• The NIS yields estimates of national, state, and selected urban area coverage for vaccines and vaccine series (e.g., 4:3:1:3:3, 4+ doses of DTaP,3+ doses of polio vaccine, 1+ dose of MCV, 3+ doses of hib, 3+ doses of hep B)

NIS is More Than One Survey...

AtlantaAtlanta

SeattleSeattle

San DiegoSan Diego

PhoenixPhoenix

El PasoEl Paso

SanSanAntonioAntonio

DallasDallas

MemphisMemphis

NashvilleNashville

IndianapolisIndianapolis

DetroitDetroit

ClevelandCleveland

ColumbusColumbus

MiamiMiami

JacksonvilleJacksonville

LosLosAngelesAngeles

SanSanJoseJose

NewNewOrleansOrleans

BirminghamBirmingham

HoustonHouston

MilwaukeeMilwaukee

PhiladelphiaPhiladelphia

NewarkNewark

NYCNYC

BostonBoston

BaltimoreBaltimore

DCDC

ChicagoChicago

NIS Methods

• Random-digit dialing• Collect information from household

– probe to identify all immunization providers – ask for permission to contact providers– registries are not routinely contacted (might change in

the future)

• NIS estimates are based on those households for which providers give us adequate data

• Responses are weighted to represent US children aged 19-35 months

NIS/Registry Comparison

• In Q3/2002 (one site) and Q4/2002 (three sites), four mature registries participated in a comparison of NIS and registry data

• Sites are not identified for reasons of confidentiality, but are three states and one city

NIS/Registry Comparison, continued

• Immunization records of children in the registry and with provider-validated NIS immunizations were compared, with care-givers’ consent to contact registry (almost 90% consented, in all sites)

• Each site had between 65 and 140 children with provider-verified immunizations during quarter of interest

NIS/Registry Comparison: goals of study

• To show feasibility of using NIS data to track progress toward the HP2010 goal of 95% participation in registries

• To determine if consulting registries (with caregivers’ consent) can benefit NIS

Limitations

• Can’t necessarily extrapolate to the population– Children with both registry data and data in NIS are

not a true random sample– results presented here are not weighted

• Can:– reach qualitative conclusions– state that the issues discussed are real– get a (very) rough sense of the seriousness of the

issues

Children with Provider-Verified Data Who Had Data in the Registry

• Percent of children with provider-verified data who had two or more vaccines in the registry (unweighted)– Site A: 88%– Site B: 73%– Site C: 80%– Site D: 60%

• These sites (and probably others) are doing a good job in capturing at least some immunizations

Children with Both Provider-Verified Data and Registry Data with

Vaccinations in NIS but Not in Registry

• Percent of children with both provider-verified and registry data with vaccinations in NIS but not in registry (unweighted)– Site A: 64%– Site B: 43%– Site C: 34%– Site D: 31%

• Registry data are of variable completeness

Children with Both Provider-Verified Data and Registry Data with

Vaccinations in Registry But Not in NIS

• Percent of children with both provider-verified and registry data with vaccinations in registry but not in NIS (unweighted)– Site A: 15%– Site B: 28%– Site C: 24%– Site D: 12%

• Registries indicate some vaccinations that NIS does not

Children with Both Provider-Verified and Registry Data that Registry Said Were

4:3:1:3:3 Complete but NIS Did Not • Percent of children with both provider-

verified and registry data that registry said were 4:3:1:3:3 complete but NIS did not (unweighted)– Site A: 3%– Site B: 10%– Site C: 6%– Site D: 2%

• Series completion differences are of concern

Children from Last Slide that had 4th dose of DTaP in Registry but Not in

NIS • ‘4th dose’ means ‘>4 doses’ as opposed to ‘<4 doses’;

not necessarily the chronologically last dose• Percent of children from last slide that had 4th dose of

DTaP in registry but not in NIS (unweighted) – Site A: 100%– Site B: 60%– Site C: 86%– Site D: 100%

• Detected series completion differences are mostly in the 4th dose of DTaP

Conclusions

• NIS data can be used to track progress toward HP 2010 goals (registry data are good, but need to improve)

• Registry data can benefit NIS– Some vaccinations (primarily 4th DTaP dose) in registry but not

in NIS• Hypothetical explanations:

– Duplicative (or otherwise erroneous) entries in registries– Some providers report some immunizations to registries but not to NIS– NIS does not identify all immunization providers for some children

• More research needed to learn reasons for discrepancies

Closing Comment

• More on NIS/registry studies in Session A5, 1:30 today, Maplewood– I encourage you to attend