Study Finds Link Between Psoriasis, NAFLD Among US Adult Outpatients

A significantly greater risk of nonalcoholic fatty liver disease (NAFLD) was shown in US adult outpatients with psoriasis vs those without, according to study findings published recently in JAMA Dermatology.

Affecting approximately 3% of US adults, psoriasis has been characterized as a systemic inflammatory disease with multiple organ systems involved that can lead to the development of several comorbid conditions, including cardiovascular diseases, diabetes, and NAFLD.

Prior research has reported a high prevalence of NAFLD among US inpatients with psoriasis, ranging from 44.3% to 65.6%, although the association between the 2 conditions in the outpatient population remains unclear.

“The association between psoriasis and NAFLD appears to be biologically plausible,” noted the study authors. “Some cytokines (interleukin [IL]–23, IL-17, and tumor necrosis factor [TNF]–α) have been known to be mechanisms in the development of psoriasis and to contribute to insulin resistance, which is associated with NAFLD development.”

Researchers conducted a population-based cross-sectional analysis of data from the National Health and Nutrition Examination Survey (NHANES) to explore the association between psoriasis and NAFLD. US adults aged 20 to 59 years who took part in NHANES during the 2003-2006 and 2009-2014 cycles were examined.

The main outcome assessed of NAFLD development was defined as a US fatty liver index score greater than 30, with sampling weights calculated according to NHANES guidelines. Several sensitivity analyses were performed, which excluded potential hepatotoxic medication use and non-Hispanic Black participants, as well as redefined NAFLD based on the hepatic steatosis index score and used inverse probability of treatment weighting.

Age, sex, race and ethnicity, educational level, family income, marital status, NHANES cycles, diabetes, metabolic syndrome, and smoking and alcohol drinking status were all accounted for as covariates in the fully adjusted multivariable logistic regression model.

A total of 5672 outpatient adults were included in the study (mean age, 38.9 years; 95% CI, 38.4-39.3 years; 51.1% female), of which 148 (3.0%) had psoriasis and 5524 (97.0%) did not have psoriasis. A total of 1558 participants (26.8%) were classified as having NAFLD, with a higher prevalence reported in those with psoriasis vs those without (32.7% vs 26.6%).

Findings of the multivariable logistic regression model showed that incidence of psoriasis was associated with a 67% greater risk of developing NAFLD (OR, 1.67; 95% CI, 1.03-2.70). Subgroup analyses indicated that psoriasis was associated with NAFLD in men (OR, 2.16; 95% CI, 1.10-4.24), those aged 20 to 39 years (OR, 2.48; 95% CI, 1.09-5.67), and among those without diabetes (OR, 1.70; 95% CI, 1.05-2.76).

There was no association observed among women, participants aged 40 to 59 years, or those with diabetes or in the obesity and metabolic syndrome subgroups.

The sensitivity analyses further found significant associations between psoriasis and NAFLD:

• exclusion of potential hepatotoxic medication use (OR, 1.72; 95% CI, 1.01-2.95)
• exclusion of non-Hispanic Black participants (OR, 1.76; 95% CI, 1.07-2.87)
• redefining NAFLD based on the hepatic steatosis index score (OR, 1.59; 95% CI, 1.01-2.50)
• use of inverse probability of treatment weighting (OR, 1.43; 95% CI, 1.09-1.86)

Several limitations were noted following the study findings, including the analysis’ cross-sectional design and the use of self-reported data for psoriasis diagnosis. Researchers concluded that the association shown between psoriasis and NAFLD may be important to consider in the context of clinicians prescribing potentially hepatotoxic medication for psoriasis management.

Reference

Ruan Z, Lu T, Chen Y, et al. Association between psoriasis and nonalcoholic fatty liver disease among outpatient US adults. JAMA Dermatol. Published online May 25, 2022. doi:10.1001/jamadermatol.2022.1609