Geographic isolation and severity of acute cholecystitis in Tokyo’s remote islands: a retrospective observational study

Geographic disparities in healthcare access remain a challenge even within universal healthcare systems. Tokyo Metropolis includes 11 inhabited remote islands where emergency gastrointestinal surgery is unavailable, requiring transfer to mainland hospitals. We evaluated the association of remote island residence with disease severity and surgical outcomes in acute cholecystitis. We retrospectively reviewed patients who underwent surgery for acute cholecystitis at Tokyo Metropolitan Hiroo Hospital between January 2021 and December 2025. Patients were classified into island and non-island groups. The outcome was moderate-to-severe acute cholecystitis, defined as Tokyo Guidelines 2018 Grade II/III. Clinical characteristics, treatment intervals, and perioperative outcomes were compared. Logistic regression was used to estimate the odds ratio for moderate-to-severe disease. A total of 106 patients were included (45 island and 61 non-island patients). The interval from symptom onset to first medical consultation was comparable between the groups (median, 1 vs. 1 day; p = 0.325), whereas island patients had longer intervals from symptom onset to admission (2 vs. 1 day; p < 0.001) and surgery ( 3 vs. 2 days; p < 0.001). Moderate-to-severe acute cholecystitis was more frequent among island patients (55.6% vs. 29.5%; p = 0.012). They also had greater blood loss (50 vs. 0 mL; p = 0.030), more frequent emergency postoperative endoscopic retrograde cholangiopancreatography (8.9% vs. 0%; p = 0.031), and longer postoperative hospital stays (10 vs. 7 days; p = 0.002). After adjustment for age and American Society of Anesthesiologists Physical Status ≥ 3, the odds ratio for moderate-to-severe disease in island versus non-island patients was 2.71 (95% confidence interval, 1.18–6.21; p = 0.018). Among patients undergoing surgery for acute cholecystitis at our referral center, island residents experienced longer intervals before admission and surgery and more frequently had moderate-to-severe disease. These findings suggest that geographic disparities in access to definitive surgical care may persist within Japan’s universal healthcare system.