BackgroundAdvance directives (ADs) have been legally regulated to promote autonomy over health decisions among patients who later lose decision-making capacity.Aims and objectivesTo analyse the differences in clinical practice at end of life among people who had completed an AD versus those who had not.MethodsRetrospective case–control study (1:2), matched by age, sex, year, cause of death and region of residence. The data sources used were the ADs registry, central registry of insured persons, hospital discharge, pharmacy and billing databases, and the mortality registry. Conditional logistic regression models (crude and adjusted by socioeconomic level) were performed. The outcome variable was the frequency of medical procedures performed during the last year of life.Results1723 people with ADs who died in Catalonia during 2014–2015 were matched with 3446 dead controls (without ADs). Thoracentesis was the procedure with the greatest reduction among women with an AD (adjusted OR (ORadj) 0.54, 95% CI: 0.32 to 0.89) in conjunction with artificial nutrition (ORadj 0.54, 95% CI: 0.31 to 0.95). Intubation was the procedure with the greatest reduction (ORadj 0.56, 95% CI: 0.33 to 0.94) among men. Slight differences could be seen in the case of cancer deaths. There were no relevant differences when adjusting by socioeconomic level.ConclusionsADs are an effective tool to adjust the realisation of some procedures at end of life. These results can help better plan for the treatment of patients with ADs, as well as increase the awareness among clinical personnel, families and the general population.