Discordance Between Physical Vulnerability Assessed by G8 and Social Support Structure in Relation to Unplanned Outpatient Visits Among Older Adults With Cancer

Purpose Social support is a domain of geriatric assessment, yet its relationship with physical vulnerability and outcomes remains unclear. We estimated the 6-month incidence of unplanned hospital visits among older outpatients with cancer and examined discordance between physical vulnerability and social support structure. Methods This retrospective study included outpatients aged 65–97 years receiving nurse-led decision-making support at a cancer center in Japan. Patients were classified into four support types by key-person relationship and cohabitation status. Physical vulnerability was assessed using the G8 screening tool. The primary outcome was 6-month unplanned hospital visits; secondary outcomes included falls, emergency hospitalization, delirium, and follow-up telephone consultations. Results Among 439 patients (median age, 78 years), 316 (72.0%) had low G8 scores (≤ 14). Patients with limited cohabitation support, particularly those living alone or with distant adult children, had relatively high G8 scores, indicating preserved physical function. Unplanned outpatient visits occurred most frequently among patients cohabiting with an older family member (30.8%), followed by socially isolated patients (15.7%) ( P  = 0.010). Emergency hospitalization and telephone consultations rates did not differ by support types. Falls were more common in patients with low G8 scores, whereas unplanned visits were not associated with G8 status. Conclusion Unplanned hospital visits among older outpatients with cancer reflect a discordance between physical vulnerability and social support structure. Despite physical robustness among socially isolated patients, unplanned visits were more frequent among those living with families. Assessing social support structures alongside frailty may help nurses identify patients needing guidance for timely help-seeking.