Meta-analysis Meta-analysis of randomized controlled trials on the safety and effectiveness of early versus delayed laparoscopic cholecystectomy for acute cholecystitis K. Gurusamy 1 , K. Samraj 2 , C. Gluud 4 , E. Wilson 3 and B. R. Davidson 1 1 Hepatopancreatobiliary and Liver Transplant Surgery, University Department of Surgery, Royal Free and University College School of Medicine, London, 2 Department of Surgery, Milton Keynes General Hospital, Milton Keynes, and 3 Health Economics Group, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich, UK, and 4 Copenhagen Trial Unit, Centre for Clinical Intervention Research, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark Correspondence to: Mr K. Gurusamy, c/o Professor B. R. Davidson, 9th Floor, University Department of Surgery, Royal Free Hospital, Pond Street, London NW3 2QG, UK (e-mail: kurinchi2k@hotmail.com) Background: In many countries laparoscopic cholecystectomy for acute cholecystitis is mainly performed after the acute episode has settled because of the anticipated increased risk of morbidity and higher conversion rate from laparoscopic to open cholecystectomy. Methods: A systematic review was performed with meta-analysis of randomized clinical trials of early laparoscopic cholecystectomy (ELC; performed within 1 week of onset of symptoms) versus delayed laparoscopic cholecystectomy (performed at least 6 weeks after symptoms settled) for acute cholecystitis. Trials were identified from The Cochrane Library trials register, Medline, Embase, Science Citation Index Expanded and reference lists. Risk ratio (RR) or mean difference was calculated with 95 per cent confidence intervals (c.i.) based on intention-to-treat analysis. Results: Five trials with 451 patients were included. There was no significant difference between the two groups in terms of bile duct injury (RR 0·64 (95 per cent c.i. 0·15 to 2·65)) or conversion to open cholecystectomy (RR 0·88 (95 per cent c.i. 0·62 to 1·25)). The total hospital stay was shorter by 4 days for ELC (mean difference −4·12 (95 per cent c.i. −5·22 to −3·03) days). Conclusion: ELC during acute cholecystitis appears safe and shortens the total hospital stay. Paper accepted 27 August 2009 Published online 24 December 2009 in Wiley InterScience (www.bjs.co.uk). DOI: 10.1002/bjs.6870 Introduction About 10–15 per cent of the adult Western population have gallstones 1–4 . Between 1 and 4 per cent become symptomatic each year 4,5 . In the UK, some 50 000 cholecystectomies are performed annually 6 , of which 70–90 per cent are carried out laparoscopically 7–10 and a third are performed for acute cholecystitis 11 . Thus, approximately 13 000 laparoscopic cholecystectomies are performed annually in the UK for acute cholecystitis. There is considerable controversy over the timing of laparoscopic cholecystectomy in acute cholecystitis. In the era of open cholecystectomy, early surgery (within 7 days of onset of symptoms) had no increased morbidity or mortality over delayed surgery (at least 6 weeks after symptoms settled) 12 . Delaying surgery increases the risks of further gallstone-related complications 12,13 . With laparoscopic cholecystectomy, there are concerns about higher morbidity rates in an emergency procedure 14–16 and the higher conversion rate to an open procedure during the acute phase 8,17 . The main reason for conversion in early laparoscopic cholecystectomy (ELC) is inflammation obscuring the view of Calot’s triangle 18 , whereas in delayed laparoscopic cholecystectomy (DLC) it is fibrotic adhesions 18,19 . Severe inflammation and fibrotic adhesions are associated with bile duct injury 20 . In the USA, about 30 per cent of patients with acute cholecystitis undergo cholecystectomy during the acute attack 8 . In the UK, only 20 per cent of surgeons perform laparoscopic cholecystectomy during acute cholecystitis 21 . The remainder allow the symptoms to settle for at least 6 weeks before performing DLC 21 . Meta-analyses Copyright  2009 British Journal of Surgery Society Ltd British Journal of Surgery 2010; 97: 141–150 Published by John Wiley & Sons Ltd