Introduction: Despite evidence in favour of cholecystectomy early during first presenting admission for most patients with acute calculous cholecystitis, variation in the timing of cholecystectomy remains evident worldwide. This dissertation characterizes the extent of variation within a large regional healthcare system, as well as addresses gaps in our current understanding of the clinical consequences and costs associated with early versus delayed cholecystectomy for acute cholecystitis. Methods: A population-based retrospective cohort of patients admitted emergently with acute cholecystitis was identified from administrative databases for the province of Ontario, Canada. First, the extent of variation across hospitals in the performance of early cholecystectomy (within 7 days of emergency department presentation) was characterized. Second, among patients discharged without cholecystectomy following index admission, the risk of recurrent gallstone symptoms over time was quantified. Third, operative outcomes of early cholecystectomy were compared to those of delayed cholecystectomy. Finally, a cost-utility analysis compared healthcare costs and quality-adjusted life-year gains associated with three management strategies for acute cholecystitis: early cholecystectomy, delayed cholecystectomy and watchful waiting, where cholecystectomy is performed urgently if recurrent gallstone symptoms arise. Results: The rate of early cholecystectomy varied widely across hospitals in Ontario (median rate 51%, interquartile range 25-71%), even after adjusting for patient characteristics (median odds ratio 3.7). Among patients discharged without cholecystectomy following an index cholecystitis admission, the probability of a gallstone-related emergency department visit or hospital admission was 19% by 12 weeks following discharge. Early cholecystectomy was associated with a lower risk of major bile duct injury (0.28%vs.0.53%, RR=0.53, 95%CI 0.31–0.90, p=0.025). No significant differences were observed in terms of open cholecystectomy (15%vs.14%, RR=1.07, 95%CI 0.99–1.16, p=0.10) or in conversion among laparoscopic cases (11%vs.10%, RR=1.02, 95%CI 0.93–1.13, p=0.68). Early cholecystectomy was on average less costly ($6,905 per person) and more effective (4.20 QALYs per person) than delayed cholecystectomy ($8,511; 4.18 QALYs per person) or watchful waiting ($7,274; 3.99 QALYs per person). Conclusions: Early cholecystectomy offers a benefit over delayed cholecystectomy in terms of major bile duct injury, mitigates the risk of recurrent symptoms, and is associated with the greatest QALY gains at the least cost.

Introduction: Despite evidence in favour of cholecystectomy early during first presenting admission for most patients with acute calculous cholecystitis, variation in the timing of cholecystectomy remains evident worldwide. This dissertation characterizes the extent of variation within a large regional healthcare system, as well as addresses gaps in our current understanding of the clinical consequences and costs associated with early versus delayed cholecystectomy for acute cholecystitis. Methods: A population-based retrospective cohort of patients admitted emergently with acute cholecystitis was identified from administrative databases for the province of Ontario, Canada. First, the extent of variation across hospitals in the performance of early cholecystectomy (within 7 days of emergency department presentation) was characterized. Second, among patients discharged without cholecystectomy following index admission, the risk of recurrent gallstone symptoms over time was quantified. Third, operative outcomes of early cholecystectomy were compared to those of delayed cholecystectomy. Finally, a cost-utility analysis compared healthcare costs and quality-adjusted life-year gains associated with three management strategies for acute cholecystitis: early cholecystectomy, delayed cholecystectomy and watchful waiting, where cholecystectomy is performed urgently if recurrent gallstone symptoms arise. Results: The rate of early cholecystectomy varied widely across hospitals in Ontario (median rate 51%, interquartile range 25-71%), even after adjusting for patient characteristics (median odds ratio 3.7). Among patients discharged without cholecystectomy following an index cholecystitis admission, the probability of a gallstone-related emergency department visit or hospital admission was 19% by 12 weeks following discharge. Early cholecystectomy was associated with a lower risk of major bile duct injury (0.28%vs.0.53%, RR=0.53, 95%CI 0.31–0.90, p=0.025). No significant differences were observed in terms of open cholecystectomy (15%vs.14%, RR=1.07, 95%CI 0.99–1.16, p=0.10) or in conversion among laparoscopic cases (11%vs.10%, RR=1.02, 95%CI 0.93–1.13, p=0.68). Early cholecystectomy was on average less costly ($6,905 per person) and more effective (4.20 QALYs per person) than delayed cholecystectomy ($8,511; 4.18 QALYs per person) or watchful waiting ($7,274; 3.99 QALYs per person). Conclusions: Early cholecystectomy offers a benefit over delayed cholecystectomy in terms of major bile duct injury, mitigates the risk of recurrent symptoms, and is associated with the greatest QALY gains at the least cost.

Background: Treatment decisions for elderly patients with gallbladder pathology are complex. Little is known about what factors go into treatment decisions in this population. We used Medicare data to examine gender-based differences in the use of cholecystectomy vs. cholecystostomy tube placement in elderly patients with acute cholecystitis. Methods: We queried a 5% random sample of Medicare data (2009-2011) for patients >65 admitted for acute cholecystitis (by ICD-9 code) who subsequently underwent a cholecystectomy and/or cholecystostomy tube placement. Demographic information (age, race), clinical characteristics (Elixhauser index, presence of biliary pathology), and hospital outcomes (case fatality rate, length of stay, need for ICU care) were compared by gender. A multivariable model was used to examine predictors of cholecystectomy vs. cholecystostomy tube placement. Results: Of 4063 patients admitted with cholecystitis undergoing the procedures of interest just over half (58%) were women. The majority of patients (93%) underwent cholecystectomy. Compared to women, men were younger (average age 76 vs. 78, p value < 0.01) and had few comorbidities (average Elixhauser 1.2 vs. 1.4 p value < 0.01). Case fatality rate was similar between men (2.5%) and women (2.4% p value 0.48). A higher percentage of men spent time in the ICU (36%) compared to women (31% p value < 0.01). On multivariable analysis men were 30% less likely to undergo cholecystectomy (OR 0.69, 95% CI 0.53-0.91). Conclusion: Elderly men are less likely than elderly women to undergo cholecystectomy for acute cholecystitis despite being younger with less co morbidity and are more likely to spend time in the ICU. More research is needed to determine whether a difference in treatment is contributing to the higher rate of ICU utilization in elderly men with acute cholecystitis.