Shared decision making (SDM) may impact medication adherence in patients with chronic respiratory diseases. Yet its actual effect and the working mechanism behind SDM remain unclear. The objective is to summarize evidence regarding SDM interventions on medication adherence and outcomes in patients with chronic respiratory diseases and unravel underlying mechanisms and critical components.

A systematic literature search was conducted in CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, Medline (Pubmed), and Psychinfo in November 2023. Randomized controlled trials were included if the study included patients with asthma, COPD or CF, an SDM intervention, and medication adherence to inhalation medication as outcome measure. Risk of bias was assessed using the Risk of Bias-2 (RoB-2) tool.

From 675 retrieved studies, four RCTs (asthma N=2, COPD N=2) met all inclusion criteria. Three of these studies showed a significant positive effect of SDM on adherence. However, considerable variation in study and intervention characteristics was found. Risk of bias was intermediate to high. In only one study, the intervention and hypotheses were based on a theoretical model. Three pathways of suggested intervention mechanisms were identified: activation, education, and personalized treatment plan.

The limited available evidence suggests a positive effect of SDM interventions on medication adherence in patients with asthma or COPD. Given the heterogeneity in study and intervention characteristics alongside the relatively low quality of the available studies, more research is needed to establish the value of SDM for improving adherence in these patients and into its underlying pathways.