Little is known about nongenetic risk factors for primary sclerosing cholangitis (PSC), except a possible protective effect of smoking.
Dr Roksund Hov and colleagues from Norway 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.
Data were analyzed from 240 patients with PSC and 245 control subjects, matched for gender and age.
A lower proportion of patients with PSC were daily coffee drinkers than control subjects, both currently and at the age of 18 years.
The associations were mainly attributed to differences observed in men.
The team found that 20% of the patients were ever daily smokers compared with 43% of control subjects.
Ever daily smoking before PSC diagnosis was associated with older age at diagnosis.
The research team noted that ever daily smoking,and being a coffee drinker at the age of 18 years were independently and negatively associated with PSC.
Fewer female patients with PSC than control subjects reported ever use of hormonal contraception.
The team observed that among female patients, there was a strong correlation between increasing number of children before the diagnosis of PSC and increasing age at diagnosis.
Dr Hov's team concludes, "Coffee consumption and smoking might protect against development of PSC."
"In women, the disease might be influenced by hormonal factors."