Prevalence estimation of significant fibrosis because of NASH in Spain combining transient elastography and histology

Background & Aims Non-alcoholic fatty liver disease (NAFLD) has become a major public health problem, but the prevalence of fibrosis associated with non-alcoholic steatohepatitis (NASH) is largely unknown in the general population. This study aimed to provide an updated estimation of the prevalence of NASH fibrosis in Spain. Methods This was an observational, retrospective, cross-sectional, population-based study with merged data from two Spanish datasets: a large (N = 12 246) population-based cohort (ETHON), including transient elastography (TE) data, and a contemporary multi-centric biopsy-proven NASH cohort with paired TE data from tertiary centres (N = 501). Prevalence for each NASH fibrosis stage was estimated by crossing TE data from ETHON dataset with histology data from the biopsy-proven cohort. Results From the patients with valid TE in ETHON dataset (N = 11 440), 5.61% (95% confidence interval [95% CI]: 2.53-11.97) had a liver stiffness measurement (LSM) >= 8 kPa. The proportion attributable to NAFLD (using clinical variables and Controlled Attenuation Parameter) was 57.3% and thus, the estimated prevalence of population with LSM >= 8 kPa because of NAFLD was 3.21% (95% CI 1.13-8.75). In the biopsy-proven NASH cohort, 389 patients had LSM >= 8 kPa. Among these, 37% did not have significant fibrosis (F2-4). The estimated prevalence of NASH F2-3 and cirrhosis in Spain's adult population were 1.33% (95% CI 0.29-5.98) and 0.70% (95% CI 0.10-4.95) respectively. Conclusions These estimations provide an accurate picture of the current prevalence of NASH-related fibrosis in Spain and can serve as reference point for dimensioning the therapeutic efforts that will be required as NASH therapies become available.