Data Linkage

All participants consented to linkage with healthcare and criminal justice records. BLISS will report the number and proportion of trial participants successfully linked to each data source overall and by trial. SAIL Databank test linkage was viable for 65% of the participants tested. NHS England linkage tests were not conducted because of recruitment delays and the Welsh-heavy early sample. NHS England will conduct linkage using exact matches on NHS number, sex, and date of birth. The Leeds Clinical Trials Research Unit will securely transfer personal identifiers to NHS England, which will return linked datasets through encrypted files. Each individual will be assigned a unique BLISS ID because some participants may have enrolled in more than one trial. The article recommends using routine data linkage as a primary or supplementary outcome source in future studies.