ISTANBUL, TURKEY – The prevalence of psoriasis was significantly greater in subjects with nonalcoholic fatty liver disease by a margin of 7% to 4.2%, according to findings from a long-term, population-based cohort study including nearly 4,000 individuals.
This newly identified link between two common diseases – one of which manifests as visible, angry skin lesions; the other silent, insidious, and often unrecognized until its late stages – contains an important message for clinicians, said Dr. Ella van der Voort of Erasmus University in Rotterdam, the Netherlands.
"Physicians should be aware of this increased risk before prescribing for psoriasis patients medications with potential for liver toxicity – and I’m not talking about just psoriasis medications, but also medications in general, like statins," she said at the annual congress of the European Academy of Dermatology and Venereology.
Dr. Ella van der Voort
Psoriasis was present in 5.1% of the study group. Most cases were mild, with affected patients having a mean psoriasis area severity index of 2.9 out of a possible 72 and no use of systemic psoriasis therapies. Nevertheless, the prevalence of nonalcoholic fatty liver disease (NAFLD) was 46.2% among the 118 psoriasis patients, compared with 33% in the 2,174 subjects without psoriasis.
NAFLD is now the most common form of chronic liver disease in Western countries. By 2020, when new well-tolerated and highly effective medications for hepatitis C are expected to have made a mark, NAFLD may be the leading reason for liver transplantation in developed countries, Dr. van der Voort observed.
The Rotterdam Study is designed to examine contributors to chronic diseases in the elderly, including cardiovascular, endocrinologic, psychiatric, neurologic, and eye diseases. The first wave of participants enrolled in 1989-93. Dr. van der Voort’s study focused on the third cohort, consisting of 3,932 elderly Rotterdam-area residents enrolled in 2006-2008. The mean age at enrollment was 76 years, and the ongoing routine evaluation of the cohort includes liver ultrasound, lab tests for liver enzyme levels and serologic evidence of hepatitis, and a skin examination.
Dr. van der Voort’s analysis was restricted to the 2,292 third-wave subjects who were not heavy drinkers and didn’t have chronic hepatitis, either of which rules out the diagnosis of NAFLD. The participants were not taking hepatotoxic medications, and there was no uncertainty as to the skin examination findings.
The hallmark of NAFLD is the accumulation of triglycerides in the hepatocytes. The previously well-described risk factors for NAFLD include the metabolic syndrome and its individual components, as well as sedentary lifestyle, smoking, and a poor-quality diet. There is also a genetic component: individuals with a mutation in the phospholipase domain-containing protein 3 (PNPLA3) gene, which codes for an enzyme functioning in hydrolyzation of triglycerides, are predisposed to NAFLD.
The prevalence of metabolic syndrome was 62% in subjects with psoriasis and 52% in those without psoriasis. Individuals with psoriasis also were more likely to be smokers by a margin of 15% to 8%. After adjusting for those variables, as well as alcohol intake, age, gender, liver enzyme levels, and other potential confounders, two strong independent predictors of NAFLD were metabolic syndrome, with an adjusted odds ratio of 3.5, and psoriasis, with an odds ratio of 1.7.
In a multivariate analysis, psoriasis was not only independently associated with a 70% increased likelihood of NAFLD, but psoriasis patients with NAFLD were also 60% more likely to have the more severe forms of NAFLD.
The Rotterdam study is funded chiefly by Dutch scientific research foundations, with secondary pharmaceutical industry support. Dr. van der Voort reported having no financial conflicts of interest.