SAF score and mortality in NAFLD after up to 41 years of follow-up

Background and aims: A new score for the histological severity of nonalcoholic fatty liver disease (NAFLD), called SAF (Steatosis, Activity and Fibrosis) has been developed. We aimed to evaluate the impact of this score on overall mortality. Methods: We used data from 139 patients with biopsy-proven NAFLD. All biopsies were graded according to the SAF scoring system and disease severity was classified as mild, moderate or severe. Causes of death were extracted from a national, population-based register. A Cox regression model, adjusted for sex, body mass index (BMI) and diabetes mellitus type 2, was applied. Results: At baseline 35 patients presented with mild or moderate disease respectively, and 69 patients with severe disease. During follow-up (median 25.3 years, range 1.7-40.8) 74 patients died, 11 in the mild group (31%), 18 in the moderate group (51%) and 45 in the severe group (65%), p=.002. Compared to patients with mild disease, patients with moderate disease did not have a significant increase in overall mortality (HR 1.83, 95% CI 0.89-3.77, p=.10). Patients with severe disease had a significant increase in mortality (HR 2.65, 95% CI 1.19-5.93, p=.017). However, when adjusting for fibrosis stage, significance was lost (HR 1.85, 95% CI 0.76-4.54, p=.18). NASH, defined as per the FLIP algorithm, was not associated with mortality compared to not having NASH (HR 1.46, 95% CI 0.74-2.90, p=.28). Conclusions: After adjustment for fibrosis, the SAF score was not associated with increased mortality in NAFLD. This finding should be corroborated in larger cohorts with similar follow-up time.