Objectives To estimate the proportions of people aged 50 years or more with mild gallstone pancreatitis who undergo index cholecystectomy (during their initial hospital admission) or interval cholecystectomy (during a subsequent admission); to compare outcomes following index and interval cholecystectomy; and to identify factors associated with undergoing interval cholecystectomy. Design, setting, participants Analysis of linked hospitalisation and deaths data for all people aged 50 years or more with mild gallstone pancreatitis who underwent cholecystectomy in New South Wales within twelve months of their index admission, 1 July 2008 - 30 June 2018. Main outcome measures Cholecystectomy classification (index or interval). Secondary outcomes: all-cause mortality (30-365 days), emergency re-admissions with gallstone-related disease (within 28 or 180 days of discharge); hospital lengths of stay (index admission, and all admissions with gallstone-related disease over six months). Results A total of 1836 patients underwent index cholecystectomy (37.9%) and 3003 interval cholecystectomy (62.1%). Mortality to twelve months was similar in the two groups. Larger proportions of people who underwent interval cholecystectomy were re-admitted within 28 days (246, 8.2% v 23, 1.3%) or 180 days (527, 17.6% v 59, 3.2%), or required open cholecystectomy (238, 7.9% v 69, 3.8%). Mean index admission length of stay was longer for index than interval cholecystectomy (7.7 [SD, 4.7] days v 5.3 [SD, 3.9] days), but six-month total length of stay was similar (8.2 [SD, 5.6] days v 7.9 [SD, 5.8] days). Interval cholecystectomy was more likely for patients with three or more comorbid conditions (adjusted odds ratio [aOR], 1.29; 95% CI, 1.08-1.55) or private health insurance (aOR, 1.31; 95% CI, 1.13-1.51), and for those admitted to low surgical volume hospitals (aOR, 1.84; 95% CI, 1.03-3.31). Conclusions Most NSW people over 50 with mild gallstone pancreatitis did not undergo index cholecystectomy, despite recommendations in international guidelines. Delayed cholecystectomy was associated with more frequent open cholecystectomy procedures and gallstone disease-related emergency re-admissions, as well as with low or medium hospital surgical volume, comorbidity, and having private insurance.
