Background: Shared decision making (SDM) is a process within the physician–patient relationship applicable to any clinical action,
whether diagnostic, therapeutic, or preventive in nature. It has been defined as a process of mutual respect and participation between
the doctor and the patient. The aim of this study is to determine the effectiveness of decision aids (DA) in primary care based on
changes in adherence to treatments, knowledge, and awareness of the disease, conflict with decisions, and patients’ and health
professionals’ satisfaction with the intervention.
Methods: A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was
conducted in Medline, CINAHL, Embase, the Cochrane Central Register of Controlled Trials, and the NHS Economic Evaluation
Database. The inclusion criteria were randomized clinical trials as study design; use of SDM with DA as an intervention; primary care
as clinical context; written in English, Spanish, and Portuguese; and published between January 2007 and January 2019. The risk of
bias of the included studies in this review was assessed according to the Cochrane Collaboration’s tool.
Results: Twenty four studies were selected out of the 201 references initially identified. With the use of DA, the use of antibiotics was
reduced in cases of acute respiratory infection and decisional conflict was decreased when dealing with the treatment choice for atrial
fibrillation and osteoporosis. The rate of determination of prostate-specific antigen (PSA) in the prostate cancer screening decreased
and colorectal cancer screening increased. Both professionals and patients increased their knowledge about depression, type 2
diabetes, and the perception of risk of acute myocardial infarction at 10 years without statins and with statins. The satisfaction was
greater with the use of DA in choosing the treatment for depression, in cardiovascular risk management, in the treatment of low back
pain, and in the use of statin therapy in diabetes. Blinding of outcomes assessment was the most common bias.
Conclusions: DA used in primary care are effective to reduce decisional conflict and improve knowledge on the disease and
treatment options, awareness of risk, and satisfaction with the decisions made. More studies are needed to assess the impact of
shared decision making in primary care.