Background & Aims:
Little is known about nongenetic risk factors for primary sclerosing cholangitis (PSC), except a possible protective effect of smoking. We investigated the relationship between environmental risk factors and susceptibility to PSC.
A questionnaire was distributed to patients with PSC, recruited from Oslo University Hospital Rikshospitalet in Norway through 2011, and randomly chosen individuals from the Norwegian Bone Marrow Donor Registry (controls). Data were analyzed from 240 patients with PSC and 245 controls, matched for sex and age.
A lower proportion of patients with PSC were daily coffee drinkers than controls, both currently (76% vs 86%; odds ratio [OR], 0.52; 95% confidence interval [CI], 0.32–0.82; P=.006) and at the age of 18 y (35% vs 49%; OR, 0.58; 95% CI, 0.40–0.83; P=.003). The associations were mainly attributed to differences observed in men. Twenty percent of the patients were ever (current or former) daily smokers compared with 43% of controls (OR, 0.33; 95% CI, 0.22–0.50; P<.001). Ever daily smoking before PSC diagnosis was associated with older age at diagnosis (42 y vs 32 y, P<.001). Ever daily smoking (P<.001) and being a coffee drinker at the age of 18 y (P=.048) were independently and negatively associated with PSC. Fewer female patients with PSC than controls reported ever use of hormonal contraception (51% vs 85%, P<.001). Among female patients, there was a strong correlation between increasing number of children before the diagnosis of PSC and increasing age at diagnosis (r=0.63; P<.001).
Coffee consumption and smoking might protect against development of PSC. In women, the disease might be influenced by hormonal factors.