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Using Birth Certificate Data for Research on Fertility Assistance: the Massachusetts Experience

Using Birth Certificate Data for Research on Fertility Assistance: the Massachusetts Experience. Bruce B. Cohen, Ph.D. Co-director, Center for Health Information and Statistics Massachusetts Department of Public Health NAPHSIS Conference June 2004. Background.

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Using Birth Certificate Data for Research on Fertility Assistance: the Massachusetts Experience

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  1. Using Birth Certificate Data for Research on Fertility Assistance: the Massachusetts Experience Bruce B. Cohen, Ph.D. Co-director, Center for Health Information and Statistics Massachusetts Department of Public Health NAPHSIS Conference June 2004

  2. Background • Massachusetts has the third highest number of Assisted Reproductive Techonology procedures (ART) performed in US and highest rate (MMWR, 4/30/04) • Massachusetts has the highest multiple birth rate in US • On the MA certificate of live birth, there are check boxes for use of ART and fertility drugs (FD) • Massachusetts provides full access to confidential data for perinatal research purposes

  3. Two projects underway • Joint research project with the CDC Division of Reproductive Health to link birth certificate data with all Massachusetts fertility clinic data to create a population-based cohort to examine risks and outcomes of ART use • Joint research project with NICHD and UMass Amherst to examine the quality of birth certificate data on FD/ART

  4. Objectives of CDC Project • To link information from CDC’s assisted reproductive technology (ART) surveillance data files with Massachusetts state birth records • To create the first US comprehensive, population-based dataset of ART mother-infant pairs which will include data on: • circumstances surrounding conception and delivery • maternal and infant outcomes

  5. Advantages of linked data file Linked dataset would allow for evaluation of ART mother-infant pairs in context of a US population: • ability to analyze various maternal and infant outcomes, including infant mortality • proper control for confounding factors • comparison group of non-ART births from MA birth cohort • potential for comparison group of births conceived with infertility drugs and no ART • potential for further file linkage and trend analyses

  6. Timeline • Receive permission for project after CDC and MDPH review: July 2001 • Develop, test and implement computer linkage algorithms: summer 2001- spring 2002 • Contact clinics for information to increase linkage rate and validate algorithm: fall 2001-summer 2002 • Create and finalize linked file for 1997-1998 births: winter, 2002 • Develop detailed analytic plans: winter 2002-fall, 2003 • Began analysis: Winter 2004 • Completing linkage of 1999-2000 data: Summer 2004

  7. Data sources • ART Registry data base: patient history, ART treatment information, ART outcome information • MA birth file: demographic characteristics, prenatal care use, maternal history, pregnancy complications, delivery outcomes and complications • ART clinics – name data: increased linkage and validation of computer algorithm using secondary identifiers

  8. Methods – Study Population The study population was drawn from MA birth certificate data base: • infants born in 1997 and 1998 • maternal residency listed as MA. • birth occurred in MA, RI, CT, NH N=161,539 total infants; 158,229 deliveries

  9. Methods – Study Population Data from live births reported to ART Registry were linked to the study population if: • ART treatment was in a MA or RI clinic (11 clinics total) • Infant(s) born in 1997 or 1998 • Maternal residency at time of ART listed as MA or unknown (because a large proportion , 45%, were missing residency data). N=3704 total infants; 2703 deliveries

  10. Methods – Study Population • For purposes of linkage, both data files -- MA birth certificate data base and ART Registry -- were organized as live-birth deliveries (i.e. infant-sets) • Upon completion of linkage, the final ART-MA linked dataset was reorganized to include each infant as a unique observation

  11. How were states chosen for inclusion in target study population? Aside from MA, only 3 states reported a relevant number of births to MA resident mothers in 1997-98 • Rhode Island (N=2083) • New Hampshire (N=429) • Connecticut (N=191) • No other states made a significant contribution Together, MA and these additional three states accounted for 99.7% of all births to MA resident mothers.

  12. Data Linkage Strategy STAGE 1: • link ART record to birth record using mothers date of birth and infant’s date of birth • further evaluate records that link using other variables in common to the data sets -- plurality, parity and birth weight STAGE 2: • further linkage by maternal name – name data for a portion of records obtained through follow-up with ART clinics

  13. Data linkage strategy, Stage 1 – expectation of success using two dates of birth variables • Review of 1997-1998 MA BC data showed that: • 97% of singleton births had unique MDOB/IDOB combinations • 99.8% of multiple births had unique combinations of MDOB/IDOB • Thus, expected duplication rate was 1-3% during Stage 1 linkage

  14. Stage 1 Linkage Results by Plurality (from ART record)

  15. Evaluation of Records that Matched* in Stage 1: Concordance Between Data Sources on Parity and Birth Weight * Matched defined as ART record matched on MDOB/IDOB with only one birth record

  16. Stage 2 Linkage, Selection of Records The following were initially selected for inclusion in Stage 2: • All records that were unmatched after Stage 1 • All records that matched with more than one birth record in Stage 1 • All records that matched with one birth record but were discordant on plurality • All records that matched with one birth record but were discordant on both parity and birth weight • A 3% random sample of records that matched with one birth record and were concordant on plurality and either parity or birth weight, or both parity and birth weight

  17. Methods: Stage 2 Algorithm for name data linkage among ART records that were unmatched after stage 1 • 1. Search for exact mother name match (first and last) • If yes, check to ensure 5 of 6 DOB variables* matched • If yes, consider record matched • If no, put record back in pool for inclusion in #2 * The 6 DOB variables are mother’s birth day, birth month, and birth year and infant’s birth day, birth month, and birth year

  18. Methods: Stage 2 Algorithm for name data linkage among ART records that were unmatched after stage 1 • 2. Search for all BC records that matched ART record on 5 out of 6 DOB variables • Examine 5/6 matches manually for concordance on name • If clear name match identified, consider record matched • If no clear name match, search for all BC records that matched ART record on 4 out of 6 DOB variables and examine all 4/6 matches manually for concordance on name • If no clear name match after 4/6 record search, search for BC records that matched ART record on all 3 MDOB or all 3 IDOB variables and examine matches manually for concordance on name

  19. Methods: Stage 2Algorithm for name data linkage among ART records that were unmatched after stage 1 For all potential name matches with less than 5/6 concordance on DOB variables, a more extensive review was undertaken in deciding whether the records matched. In addition to DOB variables and mother’s first and last name, the following were examined: parity, birth weight and plurality concordance between datasets mother’s state of residence in ART dataset – MA or unknown whether ART use and/or fertility drug use listed on BC The Steering Committee examined all data and rendered a group decision on whether a record matched. (In nearly all cases, the decision was unanimous)

  20. Maiden name review and results • Initially, name data consisted only of mother’s first and last name. Maiden names were subsequently obtained from BC dataset to check for cases of: • Possible mis-recordings of last and maiden names • Marriage between ART treatment and birth • The name algorithm was repeated for all records that remained unmatched after stages 1-3. Maiden name was substituted for last name • Only 1 additional match was found

  21. Final match rate by clinic size

  22. Final match rate by residency status

  23. Possible reasons for non-match 1) Patient received treatment in MA but actually lived in another state. This is likely to have been the case with patients who reported state of residency as unknown. 2) Patient was MA resident at the time of ART treatment but moved before delivery –i.e. migration. 3) Misclassification/data entry error of state of residency by clinics – default entry of MA. 4) Residency may have been recorded as MA for some couples who worked in MA and received MA benefits but lived in a surrounding state. 5) For some records, name data were not available from clinics, and therefore linkage status could not be verified or remained unknown (I.e. true matches that could not be reconciled).

  24. Sensitivity Analyses of Linkage Rate • Final match rate: 2413/2703 = 89.3% • If we assume: • Residency unknown – 87.75% MA residents; 12.25% non-residents • Migration rate between ART and birth was 2.5% for MA residents • Projected “true” match rate is changed to 2413/2614 = 92.3% (may be higher based on assumptions of about migration of residents between receiving fertility treatments and time of delivery) • Other issues such as data entry error on state of residence – i.e. by default mis-coding residency as MA for non-residents – might have resulted in additional sources of over-reporting in the linkage denominator. This even the projected 92% match rate might be conservative.

  25. Future Plans • Data analysis of specific topics using linked data file. • Expand project to include more recent years • Explore linkages with other data sources such as hospital discharge data base

  26. Objectives of Joint NICHD Project • To evaluate the quality of the FD/ART data provided on the hospital work sheet • To review hospital procedures for ascertainment, completion, and submission of FD/ART variables to the RVRS • To evaluate: 1) if these variables provide a useful frame work to pursue FD/ART research; 2) if not, recommend how to collect this information to improve quality of the data

  27. NICHD Project--Study 1, Methods • identify cohort of births for whom use of ART/FD was indicated on birth certificate • identify cohort of births where FD/ART use likely, but not reported (higher order multiple births to older women) • develop sampling strategy for ART only, FD only, both; stratify by hospital • develop survey instrument to collect information on fertility treatment • perform survey

  28. NICHD Project--Study 1: Timeline and Issues • Currently in final stages of MDPH approval of project • Survey instrument developed; CATI programmed • Designing sample • Field work scheduled: Summer 2004-Winter • Analysis: early 2005 • Data collected from providers on hospital work sheet vs. from parents in survey

  29. NICHD Project--Study 2 • Review process of the completion of hospital work sheet prenatal care procedures check boxes for FD and ART • document process of completion • contact sample of hospitals and interview appropriate staff about issues--where are the data found in record? Who records? etc...

  30. Summary • Massachusetts is currently involved in two projects using birth certificate data for research and evaluation of FD/ART • This is an important and rapidly expanding use of birth data • If we can accurately identify FD/ART use from bc, then many avenues of cross-sectional and longitudinal research can be implemented that will enable us to better understand the outcomes of fertility treatment assisted births

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