Interactions between chronic liver disease and inflammatory bowel disease

Liver disease was first recognized in association with idiopathic inflammatory bowel disease (IBD) over a century ago (1). The introduction of better diagnostic tools such as colonoscopy and endoscopic retrograde cholangiopancreatography during the last 25 years has strengthened the association between IBD and chronic hepatobiliary dysfunction, especially primary sclerosing cholangitis (PSC). IBD [ulcerative colitis (UC) and Crohn's disease (CD)] and PSC are both chronic conditions that can result in substantial morbidity and mortality and require coordinated medical and surgical interventions (2,–7). Since the conditions frequently coexist and the presence of one can alter the natural history or the management of the other, the study of the interaction between these illnesses is of great importance. We review the epidemiology, clinical features, treatment, and prognosis of hepatobiliary diseases associated with IBD as well as the unique clinical features of IBD associated with PSC. Hepatobiliary disease, once thought to be a rare extraintestinal manifestation of UC and CD, has become increasingly recognized in recent decades (3,–9). Measurement of the true prevalence of liver dysfunction in IBD remains unclear because of imprecise definitions, differences in diagnostic aggressiveness, and differences in IBD cohorts studied. For example, if “hepatobiliary disease” is defined as a single abnormal hepatic biochemical parameter, even if transiently elevated, the prevalence of “hepatobiliary disease associated with IBD” may be higher than 50%. On the other hand, persistently elevated hepatic biochemistries are less common, ranging from 3 to 50%, with an average of 12%, across numerous studies (10,–23) (Table 1). Estimates from population-based studies, which theoretically better represent the true spectrum of a given illness, range from 5 to 16% (11,13,–14,19,20,23), whereas studies from referral centers provide higher estimates (10,12,15,16). Several series detected a high prevalence of histologic hepatobiliary abnormalities in consecutive IBD patients undergoing intestinal resection; however, such series are prone to selection bias in that only patients with IBD severe enough to warrant resection are being studied (18,–22). Moreover, transient hepatobiliary abnormalities that seemingly have no impact on long-term prognosis have been noted in IBD patients during flares of acute colitis (19), and some of the pathologic findings in the surgical series may be the histologic correlates of such colitis-related rises in hepatic biochemistries. In summary, population-based estimates of the prevalence of hepatobiliary dysfunction of 4.5-15.6% likely represent minimal estimates, whereas studies of operative liver biopsies are likely to provide maximal estimates of prevalence.