Coffee consumption appears to protect against the development of primary sclerosing cholangitis, but not against the development of primary biliary cirrhosis, according to findings from a case-control study involving more than 1,300 subjects.
Average coffee consumption was 50 cups per month among 348 study subjects with primary sclerosing cholangitis (PSC), and those subjects spent an average of 50% of their life actively drinking coffee. Average coffee consumption among 456 healthy controls was 78 cups per month, and those subjects spent an average of 67% of their life actively drinking coffee, Dr. Craig Lammert reported during a press briefing held prior to the annual Digestive Disease Week where the findings will be presented.
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A recent study indicates that 50 cups of coffee per month could greatly reduce the risk of developing primary sclerosing cholangitis among patients with primary biliary cirrhosis.
The differences between the PSC patients and the controls were statistically significant after adjustment for age and sex, said Dr. Lammert of Mayo Clinic, Rochester, Minn.
The healthy controls and 530 subjects with primary biliary cirrhosis (PBC) did not differ significantly with respect to mean age when coffee drinking began, estimated lifetime cups of coffee per month, or percent of life spent actively drinking coffee.
Study subjects were adult patients with well-defined PBC and PSC, and healthy controls recruited between 2002 and 2013. All completed a questionnaire about their coffee drinking history and status.
The PBC patients and healthy controls differed in terms of sex (89% vs. 74% in the groups, respectively, were women), but were of similar age (66 years in both groups). The groups did not differ in terms of the percentages of current coffee drinkers and never coffee drinkers.
The PSC patient and healthy control groups differed significantly both in terms of sex composition and age (57 vs. 66 years, in the groups, respectively). Furthermore, 21% of PSC patients, compared with 13% of controls, reported never drinking coffee, and 67% of PSC patients, compared with 78% of controls, were current coffee drinkers. These differences were significant even after adjustment for age and sex.
Dr. Craig Lammert
Coffee consumption has been linked with numerous health benefits, including protective effects in the liver, but detailed evaluation of coffee use among patients with cholestatic liver disease has been lacking, according to Dr. Lammert.
These findings reveal an environmental effect divergence between PSC and PBC, which is interesting given that coffee was previously thought to be protective in advanced liver disease, said Dr. Larry Friedman, Digestive Disease Week Council chair and chair of the department of medicine at Newton-Wellesley Hospital in Newton, Mass.
"The key question to answer is, why is PBC different?" he asked, adding that PBC appears to be an "outlier that doesn’t follow the model or patterns reported to date."
Indeed, the findings are expected to spur new research into the environmental factors associated with complex liver disease, Dr. Lammert said.
As for whether patients with PSC should be encouraged to drink coffee, Dr. Lammert said the data are insufficient for making specific recommendations at this point.
"But I won’t discourage it by any means," he said.
This study was funded by grants from the National Institutes of Health and the American Liver Foundation. Dr. Lammert reported having no disclosures.