The AMND and GRBD datasets were linked by deterministic
matching of the Community Health Index (CHI) numbers, numbers
unique to patients registered with a general practice in Scotland.
CHI numbers of linked women were validated against the vital sta-
tus register to identify any deaths or migrations out of Grampian
region before 1st July 1999. Linkage of the AMND cohort to the
Scottish Morbidity Records (SMR01), death registrations (NR Scot-
land) and the Scottish Renal Registry was carried out by the Infor-
mation Services Division (ISD) of NHS Scotland using both
deterministic matching on CHI numbers and probability matching
using surname, initial of first name, date of birth and post code.