RR	rate ratio
AP	acute pancreatitis
CI	confidence interval
BMI	body mass index
APACHE II	acute physiology and chronic health evaluation
SIRS	systemic inflammatory response syndrome.
RCT	randomized controlled trial
ENI	nutrition intolerance
NOS	the Newcastle–Ottawa scale
SMD	standardized mean differences
WHO	world health organization
GRV	gastric residual volume
GI	gastrointestinal
SAP	severe AP