Introduction

The role of family or other companions during adult medical consultations may influence patient understanding and decisions, but its cognitive and decisional impacts are incompletely understood. We conducted a systematic review with narrative synthesis of human studies examining how companion presence affects patient information processing and decision outcomes in clinical settings.

Methods

A systematic search of Cochrane, PubMed, and Embase identified English-language studies published between 2000 and 2025. Of 794 records identified, 9 duplicates were removed; 785 titles and abstracts were screened, and 22 full-text articles were reviewed. Eligible studies involved adults (≥18 years) with medical decision-making capacity engaged in real-world medical decisions with an in-person companion, defined as a family member, partner, friend, or informal caregiver. Seven peer-reviewed studies met inclusion criteria, including cross-sectional, cohort, and mixed-method designs across surgical, primary care, cardiology, transplant, and cancer screening contexts. No formal risk-of-bias assessment was performed due to methodological heterogeneity.

Results

Communication and engagement outcomes were most frequently reported. Three studies demonstrated significantly increased patient verbal participation, including greater question-asking, when companions were present or actively engaged, particularly in surgical and primary care consultations. Companions often asked complementary questions regarding treatment options and next steps. Decisional outcomes were less commonly assessed. Two studies using validated measures, including the Decisional Conflict Scale, found that higher emotional distress or depressive symptoms in patients or caregivers were associated with greater decisional conflict during dyadic decision making. The remaining studies reported mixed or context-dependent effects, with limited benefit when patient–companion informational alignment or role expectations were poor.

Conclusion

Across seven heterogeneous studies, companion presence was associated with increased patient engagement but variable decisional outcomes. Findings are observational and context-specific, highlighting the importance of aligning roles and expectations to support effective shared decision making.