Association of polydoctoring and mortality among persons over 85 years with multimorbidity: a prospective cohort study in Japan

Background: Polydoctoring can increase the risk of care fragmentation among patients with multimorbidity, but its impact on health outcomes remains unclear. Aim: To determine the effects of polydoctoring, as measured by the regularly visited facilities (RVF) indicator, on patient outcomes among older individuals with multimorbidity. Design & setting: Data from the ongoing prospective cohort study, Kawasaki Aging and Wellbeing Project (KAWP), was utilised in this study. Among the 1026 KAWP participants aged 85–89 years, those with two or more chronic conditions were enrolled in this study. Method: Care fragmentation and polydoctoring was evaluated using the RVF, which is a new indicator that measures the number of medical facilities consistently involved in a patient’s care. Based on RVF, mortality was analysed using the Cox proportional hazards model, with adjustments for age, sex, frailty, and number of comorbidities. Results: A significant reduction in mortality rates was observed in participants with an RVF of ≥3 and 2–4 comorbidities (hazard ratio [HR] 0.43, 95% confidence interval [CI] = 0.18 to 0.99, P value = 0.048). However, no significant difference in mortality based on RVF was observed for those with ≥5 comorbidities. Notably, individuals with ≥5 comorbidities and an RVF of 0 had a significantly higher HR for death (HR 2.68, 95% CI = 1.05 to 6.84, P value = 0.039). Conclusion: In older patients with multimorbidity, polydoctoring may reduce mortality in patients with ≤4 coexisting conditions, but it does not significantly impact mortality in those with ≥5 conditions. These findings provide insights for healthcare decision making in managing older patients with multimorbidity.