Is Acanthosis Nigricans a useful clinical screening test for non-alcoholic fatty liver disease(NAFLD) in resource poor settings

Abstract

BACKGROUND: Acanthosis nigricans (AN) is an easily detectable papillomatosis and hyperkeratosis of the skin associated with insulin resistance. Insulin resistance is widely accepted as the underlying cause of Non- Alcoholic Fatty Liver Disease (NAFLD). Ultrasonography is the currently accepted tool to screen for NAFLD in the community, but is expensive and needs expertise. OBJECTIVES: To investigate whether AN would be an useful screening test for NAFLD in an adult Sri Lankan population. METHODS: This study was part of a community based investigation −Ragama Health Study (RHS). The study population consisted of 35−64 year old adults, selected using stratified random sampling. Consenting adults were screened by a structured interview, clinical examination, liver ultrasound and collection of 10 ml venous blood. NAFLD was diagnosed based on established ultrasound criteria for fatty liver, safe alcohol consumption and absence of serum markers for Hepatitis B and C. AN was identified by the presence of dark, thick, velvety skin in the neck, body folds and creases. Results: 3012 subjects participated in the study. AN was present significantly more frequently among NAFLD patients than normal individuals in both males (37.9% vs. 4.8%, p <0.001) and females (39.8% vs. 5.8%,p<0.001). The sensitivity, specificity, and positive predictive value of AN for NAFLD was 37.9%, 95.2%, 78.0% for males and 39.8%, 94.2%, and 81.3% for females respectively. CONCLUSION: AN is significantly more common in NAFLD than normal individuals. Although AN has a high specificity, it is not an useful test to screen for NAFLD in the community.