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Linking Community Health Index and Scottish Morbidity Records for neonates: the Grampian experience.

OBJECTIVE
To describe linking Community Health Index (CHI) records with Scottish Morbidity Records for neonates (SMR11) for the purpose of follow-up in a large clinical trial.


DESIGN
A two-stage probabilistic computer match based on date of birth, surname and postcode, supplemented with hand matching.


SETTING
Aberdeen Maternity Hospital, Grampian.


SUBJECTS
10,835 babies born in the two year period between 1 March 1993 and 28 February 1995.


RESULTS
The computerised linkage matched 89.8% of the SMR11 records to a CHI record. All of the remaining 10.2% unlinked babies were accounted for by manual checking. There were 194 (1.8%) babies who did not have a CHI record due to the baby leaving the area or dying before allocation was possible. The sensitivity of the matching was estimated at 99.9% (95% CI is 99.8% to 100%).


CONCLUSION
We were able to correctly computer match 89.7% of our babies' SMR11 records with the appropriate CHI number. We have shown that the follow-up of neonates in a clinical trial setting using record linkage between secondary and primary care systems is feasible, efficient and useful. However, this exercise would have been greatly facilitated by a unique NHS identifier common to all records.