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.