Alberta.

Methods	Retrospective record review.
Participants	First and repeat offenders analysed separately. 2763 interlock participants (6% of which had mandatory sentencing) and 28427 controls.
Interventions	After a proportion of their suspension period had been completed and an educational/interventional program completed, interlocks were installed on vehicles for six months, or until the end of their suspension. July 1987 ‐ Sept 1996
Outcomes	Survival analysis during and post interlock.
Notes	Program managed by the Driver Control Board. Quality assessment score 19/27
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	D ‐ Not used