Effectiveness of a brief advance directive intervention in primary care: a randomized clinical trial

•5.4 % of patients in a randomized controlled trial filed an advance directive (AD).•The intervention consisted of a short oral and written explanation about Ads.•The intervention did not result in greater uptake of Ads.•The intervention increased interest in Ads. To measure the effectiveness of a brief intervention aimed at increasing interest in and use of advanced directives (AD) among primary care patients. Randomized controlled trial. In the intervention arm, patients were given brief oral information and a leaflet on AD by General Practitioners (GPs), in the control group were briefly informed about the study’s purpose. Outcome variables were the proportion of patients who expressed interest in AD and those who completed one. Covariates were sex, age, education, race, Charlson comorbidity index (CCI), religion, and possession of financial will. Overall, 332 patients were recruited; 58 in the intervention and 36 in the control group expressed interest in AD (p = 0.033) and 18 (5.4 %) made an AD (nine in each group). Variables associated with interest were Caucasian race (odds ratio [OR], 1.88), the intervention (OR, 1.86), and CCI extreme scores (OR, 0.36). Variables associated with AD completion were primary education/no schooling (OR, 5.69) and fewer children (OR, 0.57). A brief oral and written intervention delivered by GP significantly increased interest in AD and achieved a completion rate of 5.4 %, without differences with the control group. AD interventions should focus on individuals already likely to be motivated.