Problems with NASH? HAIR is some help: Dixon JB, Bhathal PS, O’Brien PE, Nonalcoholic Fatty Liver Disease: Predictors of Nonalcoholic Steatohepatitis and Liver Fibrosis in the Severely Obese, Gastroenterology 2001;121:91–100

The incidence of obesity in the western population in recent decades has grown enormously. Study estimates suggest that 15–20% of the U.S. population is obese (BMI ≥ 30kg/m2) (1, 2). As a consequence, concern for a possible impending epidemic of nonalcoholic fatty liver disease (NAFLD) has also risen. NAFLD has a broad pathologic spectrum which ranges from nonalcoholic steatohepatitis or NASH (probably a precursor to cirrhosis) to simple fatty infiltration of the liver or steatosis (a relatively benign liver condition). In an obese patient, with or without abnormal liver enzymes, there is currently no single laboratory or imaging test which can accurately separate steatosis from NASH. Recently, however, researchers from the University of Melbourne, Australia have proposed a relatively simple scoring system to aid in determining who among the severely obese (BMI ≥ 35kg/m2), are at risk for NASH and should be singled out for liver biopsy. The HAIR score combines the presence of hypertension (diagnosed by standard technique), elevated ALT (>40 IU), and Insulin Resistance index (>5.0) as a simple sum. Each component of the HAIR score is equally weighted and assigned a value of one. A severely obese, hypertensive patient whose insulin resistance index is <5.0 and whose ALT is <40 IU would have a HAIR score of 1. The same patient with hypertension and an elevated insulin resistance index would have a HAIR score of 2, and so on. A HAIR score of 2 provides, according to the authors, the best combination of sensitivity (0.8) and specificity (0.89) for predicting NASH. A HAIR score of 3 virtually assures the presence of NASH. The selection of the three variables which compose the HAIR score was arrived at in a prospective study of 105 consecutive patients being considered for laparoscopic placement of an adjustable gastric band with the intent of surgically enhancing weight reduction. Each patient had a laparoscopic liver biopsy at the time of gastric band placement. Steatosis, inflammation, and fibrosis were all graded on a four-point scale and correlated with clinical as well as laboratory variables. A rigorous effort to exclude patients with liver disease due to other causes was made. A multitude of variables were considered and found to be predictive of histologic findings. Many of the variables considered, most of which were eventually excluded from the HAIR score, were components of the obesity related disorder, Syndrome X. The independent predictive value of each variable was assessed in consideration of a restrictive definition of NASH. A diagnosis of NASH was based on steatosis and two of the following three (zone 3-centric features): (1) necro-inflammatory foci with mononuclear cells and/or neutrophils, (2) ballooning degeneration of hepatocytes with or without Mallory bodies, and (3) pericellular fibrosis. Although other variables were predictive of the individual histologic features above mentioned, only those eventually assimilated as components of the HAIR score had independent predictive value for the strict definition used for NASH in this study.