Table 2.

Effects of hospital volume (as a continuous variable) on outcomes in patients with severe acute pancreatitis (n = 22,551)

Outcomes	Crude OR or percent change (95% CI)	Adjusted OR or percent change (95% CI)
		Model 1*	Model 2†
Hospital LOS	−0.08% (-0.28%, 0.12%)	−0.06% (-0.25%, 0.13%)	−0.10% (-0.26%, 0.05%)
R-squared	--	22.74%	30.31%
Hospital charges	−0.17% (-0.32%, -0.01%)	−0.14% (-0.33%, 0.06%)	−0.16% (-0.27%, -0.04%)
R-squared	--	53.92%	64.16%
Hospital mortality	0.999 (0.994, 1.003)	0.995 (0.993, 0.998)	0.999 (0.996, 1.002)
c statistic	--	85.4%	93.0%

OR: odds ratio; CI: confidence interval; LOS: length of stay.

^* Covariates in model 1 included age (as a continuous variable), sex, year of admission, Charlson-Comorbidity Index (categorized as 0,1,2 and ≥3), urbanization, hospital level, the ownership of hospital, the region of hospital, causes of acute pancreatitis (categorized into biliary, alcohol-related, both or others), intensive care unit admission, organ failure, gastrointestinal bleeding and local complication.

^† Model 2 enrolled all covariates of model 1 and additional treatment covariates, including cholecystectomy, total parenteral nutrition, vasopressors, hemodialysis and mechanical ventilation.