APOLIPOPROTEIN E4 GENOTYPE AND GALLBLADDER MOTILITY INFLUENCE SPEED OF GALLSTONE CLEARANCE AND RISK OF RECURRENCE AFTER EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY

Extracorporeal shock-wave lithotripsy (ESWL) is an effective treatment in selected gallstone patients, but stone recurrence is a major drawb ack, Factors potentially influencing gallstone clearance and recurrenc e were studied in 84 patients in whom stone dissolution was diagnosed after ESWL plus bile salt therapy for initial solitary (n = 55) or mul tiple (n = 29) radiolucent stones. Apolipoprotein E (apoE) genotyping and gallbladder motility (sonography) were studied in a representative subgroup of patients (n = 50), The median follow-up after ESWL was 36 months (range, 4.5-67 months), Gallstone clearance was achieved after 8.7 months (range, 0.2-30 months), independent factors significantly enhancing gallstone clearance were the presence of E4 allele; small in itial gallstone size and number; effectiveness of fragmentation; and g ood gallbladder emptying (P = .002), Gallstone recurrence was seen in 30 patients after 18.6 months (range, 1.0-50 months), Cumulative galls tone recurrence rate (life-table analysis) was 15% within 1 year, incr easing to 60% within 5.5 years, Although the probability of gallstone recurrence tended to be smaller in patients with initial solitary ston es than in those with multiple stones during early follow-up, differen ces disappeared after long-term follow-up. Effective gallbladder empty ing (residual volume less than or equal to 6 mL) and apolipoprotein E4 (apoE4) independently influenced gallstone recurrence, Recurrence rat e was higher (log rank test, P = .037) in those patients who were homo zygous and heterozygous for the E4 allele compared with the individual s who were not expressing the apoE4 allele, Accordingly, there was an overrepresentation of the allele frequency for E4 in the group with ga llstone recurrence (P = .03), Patients with small postprandial residua l gallbladder volumes (less than or equal to 6 mL) had a lower probabi lity of stone recurrence than those with large residual gallbladder vo lumes (log rank test, P = .0215), Biliary pain was more frequent with recurrence (55% vs, 13%, P = .001), The present study indicates that a poE4 genotype is associated with increased speed of gallstone clearanc e as well as a high risk of recurrence after ESWL, This finding points to a possible role for genetic factors in the pathogenesis of cholest erol gallstones, Effective gallbladder emptying is important for speed of clearance and prevention of recurrence, Patients with initial soli tary stones have a decreased early- but not long-term gallstone recurr ence rate.