ORIGINAL ARTICLE Association between hospital volume and outcomes of elderly and non-elderly patients with acute biliary diseases: A national administrative database analysis Atsuhiko Murata, 1 Shinya Matsuda, 1 Kazuaki Kuwabara, 2 Yukako Ichimiya, 1 Yasufumi Matsuda, 1 Tatsuhiko Kubo, 1 Yoshihisa Fujino, 1 Kenji Fujimori 3 and Hiromasa Horiguchi 4 1 Department of Preventive Medicine and Community Health, School of Medicine, University of Occupational and Environmental Health, 2 Department of Health Care Administration and Management, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 3 Division of Medical Management, Hokkaido University Hospital, Hokkaido and 4 Department of Health Management and Policy, Graduate School of Medicine, Tokyo University, Tokyo, Japan Aim: This study aimed to investigate the relationship between hospital volume and clinical outcomes of elderly and non-elderly patients with acute biliary diseases using data from a national administrative database. Methods: Overall, 26 720 elderly and 33 774 non-elderly patients with acute biliary diseases were referred to 820 hospitals in Japan. Hospital volume was categorized into three groups based on the case numbers during the study period: low-volume, medium-volume and high-volume. We compared the risk-adjusted length of stay (LOS) and in-hospital mortality in relation to hospital volume. These analyses were stratified according to the presence of invasive treatments for acute biliary diseases. Results: Multiple linear regression analyses showed that increased hospital volume was significantly associated with shorter LOS in both elderly and non-elderly patients with and without invasive treatments. Increased hospital volume was significantly associated with decreased relative risk of in-hospital mortality in elderly patients. The odds ratio for high-volume hospitals was 0.672 in elderly patients without invasive treatments (95% confidence interval [CI] 0.533–0.847, P = 0.001) and 0.715 in those with invasive treatments (95% C, 0.566–0.904, P = 0.005). However, no significant differences for in-hospital mortality were seen in non-elderly patients with and without invasive treatments. Conclusion: This study has highlighted that higher volume hospitals significantly reduced LOS and in-hospital mortality for elderly patients with acute biliary diseases, but not non-elderly patients. The current results are of value for elderly healthcare policy decision-making, and highlight the need for further studies into the quality of care for elderly patients. Geriatr Gerontol Int 2012; ••: ••–••. Keywords: aged, critical care, decision making, healthcare quality improvement, management. Introduction The World Health Report has highlighted accelerated population aging worldwide, with the number of elderly people dramatically increasing in many countries. 1 As a result of this aging of society, the problem of providing appropriate emergency care is becoming increasingly important in the elderly. Since Luft et al. 2 reported a correlation between hospital volume and patient out- comes, health policy measures advocating high hospital volume have been predicated on the overwhelming empirical evidence of the hospital volume–outcome relationship for a wide variety of surgical procedures and medical conditions. 3–7 Over the past decade in par- ticular, many studies have focused on the effect of hos- pital volume on elderly patients, suggesting that hospital volume is a significant independent indicator of clinical outcomes of elderly patients. 4–7 Acute biliary diseases are the leading abdominal causes of emergency care in the elderly. 8–10 These have a wide spectrum of clinical courses, ranging from a mild form with minimal morbidity, to a severe form with a high incidence of complications and a high risk of Accepted for publication 19 July 2012. Correspondence: Dr Atsuhiko Murata MD, Department of Preventive Medicine and Community Health, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan. Email: amurata@med.uoeh-u.ac.jp Geriatr Gerontol Int 2012 © 2012 Japan Geriatrics Society doi: 10.1111/j.1447-0594.2012.00938.x | 1