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We, and others, have previously identified factors associated with severe biliary infections: biliary bacteria, age, sex, choledocholithiasis, pigment stones. Recently we reported that a low/normal BMI was associated with more severe biliary infections. To understand this association, we studied correlations between plasma lipid levels and biliary infections. METHODS: 475 patients with gallstones were studied; 410 men, 65 women; average age 62 (range 17-104). Gallstones, bile, and blood(as applicable) were cultured, Stone type recorded. Illness severity was classified as: none (no inflammatory manifestations), SIRS (fever, leukocytosis), severe (abscess, cholangitis, empyema), or MODS (bacteremia, hypotension, organ failure). Using bivariate and multivariate analysis, we examined associations between lipid levels (HDL, LDL, Triglycerides - obtained prior to the acute illness) and: BMI, biliary bacteria, bacteremia, gallstone type, illness severity. In the multivariate analysis we used factors associated with biliary infections (age, sex, biliary bacteria, pigment stones, choledocholithiasis). RESULTS: On bivariate analysis(Table), BMI correlated with HDL and Trig (P<0.003). LDL inversely correlated with biliary bacteria (P=0.002) and pigment stones (P=0.0001); while HDL and LDL inversely correlated with bacteremia (P<0.03). HDL and LDL inversely correlated with increasing infection severity (P<0.02) and MODS manifestations (P<0.006). On Multivariate analysis of factors associated with pigment stones and biliary bacteria, LDL inversely correlated with pigment stones (P=0.001) and biliary bacteria (P=0.017). Multivariate analysis of factors associated with biliary infection severity revealed HDL as the most important lipid(Figure); only HDL inversely independently correlated with biliary infection severity(P=0.007) and MODS manifestations(P=0.005). These findings held in the subgroup with biliary bacteria; and HDL independently correlated with illness severity even among patients with bacterial-laden CBD stones. CONCLUSION: This study demonstrates the importance of plasma lipids to biliary infections. Increased LDL levels favored cholesterol (rather than pigment) gallstone formation, and were more often associated with a sterile biliary tract. HDL levels, however, seemed to dictate the course of the biliary infection; patients with low HDL levels had significantly more severe biliary infections. Even among patients with bacterial-laden CBD stones, those with high HDL levels had a mild illness, while those with low HDL levels more often had MODS manifestations. This data suggest that HDL may be protective in biliary infections; and that patients with biliary infections and low HDL levels may need a more aggressive clinical approach. This is the first study to demonstrate the importance of plasma lipid levels to the severity of biliary infections.
Bivariate Analysis: Lipids and Biliary Infections

		N	HDL mg/dl	P value	LDL mg/dl	P value	Triglycerides mg/dl	P value
Stone Type	Pigment	244	42	NS	96	0.0001	156	NS
	Cholesterol or Mixed Chol	231	43		120		164
Biliary Bacteria	Bacteria	238	42	NS	101	0.002	150	0.046
	Sterile	237	43		116		174
Bacteremia	Bacteremia	39	36	0.017	85	0.006	131	NS
	Sterile blood	436	43		109		163
MODS findings (pts with biliary bacteria)	Present	72	35	0.0001	89	0.006	149	NS
	None	166	45		105		150
MODS findings (pts with bacterial-laden CBD stones)	Present	42	33	0.005	86	0.074	153	NS
	None	65	46		103		151