title: Record linkage to obtain birth outcomes for the evaluation of screening biomarkers in pregnancy: a feasibility study.
abstract: BACKGROUND
  Linking population health data to pathology data is a new approach for the evaluation of predictive tests that is potentially more efficient, feasible and efficacious than current methods. Studies evaluating the use of first trimester maternal serum levels as predictors of complications in pregnancy have mostly relied on resource intensive methods such as prospective data collection or retrospective chart review. The aim of this pilot study is to demonstrate that record-linkage between a pathology database and routinely collected population health data sets provides follow-up on patient outcomes that is as effective as more traditional and resource-intensive methods. As a specific example, we evaluate maternal serum levels of PAPP-A and free beta-hCG as predictors of adverse pregnancy outcomes, and compare our results with those of prospective studies.
  
  
  METHODS
  Maternal serum levels of PAPP-A and free beta-hCG for 1882 women randomly selected from a pathology database in New South Wales (NSW) were linked to routinely collected birth and hospital databases. Crude relative risks were calculated to investigate the association between low levels (multiples of the median < or = 5th percentile) of PAPP-A or free beta-hCG and the outcomes of preterm delivery (<37 weeks), small for gestational age (<10th percentile), fetal loss and stillbirth.
  
  
  RESULTS
  Using only full name, sex and date of birth for record linkage, pregnancy outcomes were available for 1681 (89.3%) of women included in the study. Low levels of PAPP-A had a stronger association with adverse pregnancy outcomes than a low level of free beta-hCG which is consistent with results in published studies. The relative risk of having a preterm birth with a low maternal serum PAPP-A level was 3.44 (95% CI 1.96-6.10) and a low free beta-hCG level was 1.31 (95% CI 0.55-6.16).
  
  
  CONCLUSIONS
  This study provides data to support the use of record linkage for outcome ascertainment in studies evaluating predictive tests. Linkage proportions are likely to increase if more personal identifiers are available. This method of follow-up is a cost-efficient technique and can now be applied to a larger cohort of women.
authors: Perinatal Research, Kolling Institute of Medical Research, University of Sydney, Syndey, NSW, Australia. samlain@med.usyd.edu.au
authors: Samantha J
authors: SJ
authors: Lain
authors: Charles S
authors: CS
authors: Algert
authors: Vitomir
authors: V
authors: Tasevski
authors: Jonathan M
authors: JM
authors: Morris
authors: Christine L
authors: CL
authors: Roberts
mesh_terms: D001315:Australia; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D003362:Cost-Benefit Analysis; D016208:Databases, Factual; D005240:Feasibility Studies; D005260:Female; D005313:Fetal Death; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008403:Mass Screening / Q000191:economics / Q000379:methods*; D008498:Medical Record Linkage; D011237:Predictive Value of Tests; D011247:Pregnancy / Q000097:blood*; D011256:Pregnancy Outcome; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D047928:Premature Birth
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A