1. APHA, Nov. 2006 Improving the linkage of deliveries over time using vital records and hospital discharge data Mark McLaughlin, Judy Weiss, ScD, Milton Kotelchuck, MPH, PhD, MA, Stephen Evans, MPH Boston University School of Public Health Dept. of Maternal and Child Health Boston, MA, November 6, 2006 Contact info: Mark.E.Mclaughlin@state.ma.us

2. APHA, Nov. 2006 Why link successive deliveries? Create a reproductive history of individual women to study, for example: –Risk of maternal and infant morbidity –Risk & consequences of premature birth –Impact of OB practices (e.g., method of delivery) on subsequent birth outcomes Past linkage efforts in the US have been limited and/or have ended –Birth certificates +/- fetal death certificates Need for improved ‘case-finding’ methods to capture most complete maternal linkage possible

3. APHA, Nov. 2006 Pregnancy to Early Life Longitudinal (PELL) Data System CDC-funded collaborative project MCH Dept. Boston Univ. School of Public Health MA Department of Public Health (MDPH) A population-based relational data system connected by unique identifiers for infants, deliveries and mothers Consists of a Core plus additional program and other surveillance data Is longitudinal and expandable

4. APHA, Nov. 2006 PELL Data System Early Intervention WIC (2006) Emergency Department Other Future Data Sets (e.g., School, ‘ART’, NICU, Medicaid) CORE Other DPH programs (future) Geocoded birth data (2006) Non-birth hospital discharge Birth Certificate Hospital Discharge (HD) Mother’s delivery Fetal DeathHospital Discharge (HD) Child’s birth Program Participation Data Observational Stays Health Services Utilization Data Vital and Health Status Data Linked birth-infant deaths Child and Mother deaths Birth Defects Registry Pregnancy-associated deaths Newborn Hearing Screening (2006) 2000 Census (2006) Other contextual data (e.g., environmental data) Contextual Data

5. APHA, Nov. 2006 PELL Core Data Sets Birth and Fetal Death Certificate with Hospital Discharge Maternal Delivery Record and Child Birth Record Birth Certificate Hospital Discharge (HD) Mother’s delivery Fetal DeathHospital Discharge (HD) Child’s birth CORE

6. APHA, Nov. 2006 Creation of PELL Core Linkages Birth/fetal death to Hospital records Deterministic and probabilistic linkage methodology using LinkPro 2.0 (SAS- based) software Core Linkage Variables: –Facility code –Maternal Date of Birth –Date of Delivery –Zipcode No Unique Identifier

7. APHA, Nov. 2006 PELL Core Data Linkage Rates 1998-2004 574,442 occurrence live births and fetal death records –Overall, 98.6% linked to maternal hospital delivery record –77.8% of fetal deaths linked to maternal hospital delivery record Now that the data are linked…

8. APHA, Nov. 2006 …can we create a better maternal linkage? Is there a way to combine Vitals (both births and fetal deaths) and Hospital Discharge data to create a more robust maternal linkage?

9. APHA, Nov. 2006 Creation of longitudinally-linked delivery data 3-step process using vital records and HD data individually and jointly Step 1: identify unique women within each data source and count the number of deliveries per woman –Vitals linkage based on names, DOB –HD linkage based on encrypted SSN and/or facility code plus medical record number

10. APHA, Nov. 2006 Example Hospital Discharge UHIN*MRN**DOB XZ9432012345611/16/70 XZ9432012345611/16/70 XZ9432012345611/16/70 # of delivs 3 3 3 Vitals First name Last name DOB JudyMiller11/16/70 JudyMiller11/16/70 2 3 # of delivs 2 2 * Encrypted SSN ** Medical record number

11. APHA, Nov. 2006 Creation of longitudinally-linked delivery data Step 2: Merge vital records and HD data by delivery and compare the number of deliveries –Three scenarios Both classify equal number of deliveries (92.8%) Vitals classifies more deliveries than HD (5.5%) HD classifies more deliveries than Vitals (1.7%) Accept whichever data (Vitals or HD) classified more deliveries

12. APHA, Nov. 2006 Example Vitals data First name Last name DOBDelivery date JudyMiller11/16/706/1/98 JudyMiller11/16/7012/1/00 Hospital Discharge data UHINMRNDOBDelivery date XZ9432012345611/16/706/1/98 XZ9432012345611/16/7012/1/00 XZ9432012345611/16/709/1/02JudiMillar11/16/709/1/02

13. APHA, Nov. 2006 Creation of longitudinally-linked delivery data Step 3: Assess validity of linkages –Validate names Compare names from first delivery to names from all subsequent deliveries using SPEDIS function in SAS Women with at least one name that appears significantly different (score>30) are flagged for manual review When reviewing names, judgment of validity is made based on names, dates, parity, and other demographic variables Review performed by two people and compared

14. APHA, Nov. 2006 Examples Correct maternal link First nameScoreLast nameScoreDelivery dateParity Judy0Miller06/1/981 Judy0Miller012/1/002 Judi25Millar169/1/023 Incorrect maternal link First nameScoreLast nameScoreDelivery dateParity Jennifer0Smith03/1/981 Jennifer0Smyth209/1/992 Barbara104Jones1209/5/995

15. APHA, Nov. 2006 Creation of longitudinally-linked delivery data Step 3, cont’d: Assess validity of links –Validate short inter-pregnancy intervals Calculate the time between deliveries Women with short delivery intervals (<250 days) are output for review Review performed by two people and compared –After review, maternal ID is assigned

16. APHA, Nov. 2006 Creation of longitudinally-linked delivery data RESULTS (1998-2004): 427,817 unique women identified 122,094 women found with >1 delivery –118,860 women found with >1 delivery in Vitals alone –114,014 women found with >1 delivery in HD alone 2.7% more women with >1 delivery than Vitals alone ~500 women with >1 delivery saw additional increase in deliveries

17. APHA, Nov. 2006 Practical Challenges Incomplete information –Early fetal losses (prior to 20 weeks) –Non-occurrence fetal deaths –Births to women who move out of state Initial linkage can be time consuming (if spanning several years) –Subsequent years require less time –350-400 records reviewed each year

18. APHA, Nov. 2006 Conclusions Using 3 data sources (births, fetal deaths, hospital discharge data) provides a more complete reproductive history than births and fetals alone Validation of linkages makes final data linkage more robust Longitudinally-linked delivery data provide a rich source for exploration of MCH issues

19. APHA, Nov. 2006 Caveats Vitals data –Name changes (marriage, divorce, etc.) –Spelling errors, typographical errors Hospital Discharge data –Only includes births in MA hospitals (no home births, out of state births, most births at birthing centers –Encrypted SSN (UHIN) sometimes missing (n=32,963 [5.6%]) so reliance on medical record number and assumption that woman goes to the same hospital –No Hospital Discharge data on unlinked deliveries (n=14,021 [2.5%])