Total bile acid better reflects the early biochemical biliary drainage response after endoscopic retrograde cholangiopancreatography

Table 6 Unified generalized estimating equation model comparing total bile acid, gamma-glutamyl transferase, and alkaline phosphatase after endoscopic retrograde cholangiopancreatography

Variable	Estimate	SE	Wald χ2	P value
Marker: GGT (vs TBA at 24 hours after ERCP)	1.537	0.057	725.857	< 0.001
Marker: ALP (vs TBA at 24 hours after ERCP)	1.566	0.056	793.137	< 0.001
Time: 5 days after ERCP vs 24 hours after ERCP (for TBA)	-0.719	0.086	70.145	< 0.001
Interaction: GGT × 5 days after ERCP	0.523	0.089	34.226	< 0.001
Interaction: ALP × 5 days after ERCP	0.616	0.087	49.795	< 0.001

The unified model was based on the log-transformed postoperative-to-baseline ratio and was adjusted for diagnosis category and drainage strategy. Positive coefficients for marker terms indicate smaller relative declines than total bile acid at 24 hours after endoscopic retrograde cholangiopancreatography. Significant interaction terms indicate temporal patterns that differ from that of total bile acid between 24 hours and 5 days after endoscopic retrograde cholangiopancreatography. ERCP: Endoscopic retrograde cholangiopancreatography; TBA: Total bile acid; GGT: Gamma-glutamyl transferase; ALP: Alkaline phosphatase.