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Michigan Newborn Screening & Live Births Records Linkage and
Follow-Up of Potentially Un-Screened Infants
Steven J. Korzeniewski, MA, MSc,Maternal & Child Health Epidemiology Section
Manager
Violanda Grigorescu, MD, MSPH, Glenn E. Copeland, BS, William I. Young, Ph.D.,
Michigan Department of Community Health
Outline •Background/Intent of linkage •Methods (software, data management,
algorithm)•Results•Discussion•Public Health Implications
Background•Linkages re-initiated to identify live births
potentially unscreened. ▫Initial efforts were not sustainable
•Intended to be mutually beneficial to newborn screening follow-up program and vital records. ▫Means to assess data quality
Methods• Data received from November 2007 through
March 2008 were used for this study▫ 2008 transitioned from DOS based to Web based
electronic birth certificate system▫ Newborn screening card number included on birth
record
• SAS v9.1 (Cary, N.C.) used to create text files
• Record linkage and follow-up conducted by NBS Follow-up Program▫ Newborn screening & Michigan Care Improvement
Registry (MCIR) data used for follow-up
Methods•Linkage via Link Plus
▫A probabilistic record linkage program ▫Developed for cancer registries at the
Centers for Disease Control and Prevention’s (CDC) Division of Cancer Prevention and Control in support of CDC's National Program of Cancer Registries (NCPR).
▫Can be used with any type of data in fixed width or delimited format
▫Free $$
Methods•Linkage score (probabilistic linkage)
▫based on the theoretical frame work developed by Fellegi and Sunter (1969)
▫sum of the logarithm of odds across all matching variables, based on the probability that a matching variable agrees given that a comparison pair is a match and the probability that a matching variable agrees given that a comparison pair is not a match
Methods•Blocking variables - used to ‘block’ (or
partition) the two files
•Matching variables are compared between records matching on the blocking variable.
Blocking Variables Matching Variables
Name Phonetic System
Name Matching Method
Mother's First Name
Soundex10
Mother's First NameFirst Name
Mother's Last Name
Infant’s First Name
Mother's Last Name Last Name
Infant’s Last Name
Mother's Zip Code Zip-Code
NBS Card Number* Value-Specific
Birth Order
Mother's Birth Date
Infant’s Birth Date
Mother's SSN
Mother’s medical Record Number
Methods
Methods•Follow-up
▫Unmatched records sent to follow-up staff▫Staff search NBS data▫Contact birth hospital▫Send certified letter to parent requesting
screen or signed refusal letter
ResultsBirth
YearTotal Expired
InfantsMatched Un-Matched
Excluding Expired
N N N % N %
2007 123,981
383 122,515 98.8 1,083 0.9
2008 18,197 51 18,075 99.3 71 0.4
Total 142,178
434 140,590 98.9 1,154 0.8
ResultsFollow-up Result Frequency %
NBS Already Completed 286 45.5
Parental Refusal of Screening Received Via Follow-up Staff 48 7.6
N/A (Aged > 1 year) 8 1.3
Out of State 14 2.2
Parental Refusal at Time of Screening 32 5.1
Expired 6 0.95
Lost to Follow-Up/Pending 188 29.9
Discussion • Probabilistic linkage is subjective………. & useful
• Linkage success is a function of▫ Cutoff selection▫ Data quality ▫ Strategy▫ An ability to deal with discordance
• Match rates change over time and may require alternations in linkage algorithms▫ Manual checking of initial linkage results and follow-up
results must be used to determine algorithm changes and avoid false matches.
• Live Births to NBS data matching is a “best case” scenario given data are collected at virtually the same time, same place, and often by the same person.
Discussion • Significant investment of time for
▫ Initial data management programming▫ Understanding how to select algorithm▫ Determination of borderline matches▫ Assessment of follow-up results
• Benefits beyond identification of potentially unscreened children include▫ Data quality check▫ Link to various datasets through vital records (i.e.-
birth defects, EHDI, etc.)
Public Health Implications•Link Plus is applicable to MCH databases
•Linkage facilitates data usage with minimal cost investments
•Linkage is successful at detecting unscreened infants (we have identified several)
•However, linkage should be handled with caution
Acknowledgements•Co-investigators: Violanda Grigorescu,
MD, MSPH, Glenn E. Copeland, BS, William I. Young, Ph.D.,
•NBS Follow-up Staff
