Objective The full phenotypic expression of non-alcoholic fatty liver disease (NAFLD) in lean subjects is incompletely characterised. We aimed to investigate prevalence, characteristics and long-term prognosis of Caucasian lean subjects with NAFLD.
Design The study cohort comprises 1339 biopsy-proven NAFLD subjects from four countries (Italy, UK, Spain and Australia), stratified into lean and non-lean (body mass index (BMI) </≥25 kg/m2). Liver/non-liver-related events and survival free of transplantation were recorded during the follow-up, compared by log-rank testing and reported by adjusted HR.
Results Lean patients represented 14.4% of the cohort and were predominantly of Italian origin (89%). They had less severe histological disease (lean vs non-lean: non-alcoholic steatohepatitis 54.1% vs 71.2% p<0.001; advanced fibrosis 10.1% vs 25.2% p<0.001), lower prevalence of diabetes (9.2% vs 31.4%, p<0.001), but no significant differences in the prevalence of the PNPLA3 I148M variant (p=0.57). During a median follow-up of 94 months (>10 483 person-years), 4.7% of lean vs 7.7% of non-lean patients reported liver-related events (p=0.37). No difference in survival was observed compared with non-lean NAFLD (p=0.069).
Conclusions Caucasian lean subjects with NAFLD may progress to advanced liver disease, develop metabolic comorbidities and experience cardiovascular disease (CVD) as well as liver-related mortality, independent of longitudinal progression to obesity and PNPLA3 genotype. These patients represent one end of a wide spectrum of phenotypic expression of NAFLD where the disease manifests at lower overall BMI thresholds.
Lay summary NAFLD may affect and progress in both obese and lean individuals. Lean subjects are predominantly males, have a younger age at diagnosis and are more prevalent in some geographic areas. During the follow-up, lean subjects can develop hepatic and extrahepatic disease, including metabolic comorbidities, in the absence of weight gain. These patients represent one end of a wide spectrum of phenotypic expression of NAFLD.
- nonalcoholic steatohepatitis
- fatty liver
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QMA and EB are joint senior authors.
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Contributors Manuscript concept and design: RY, EB and QMA, writing: RY, data collection: RY, OG, SP, LM, DT, AB, ED, FMV, MM, DC, DM, MJP, ALF, RA, CR, JA, RG-D, AA, GPC, MYWZ, AL, PF, GP, AG, ME, LV, JG, MR-G, QMA and EB, statistical analyses: RY, EB, PF and QMA, revision and editing: EB, QMA, LV, JG and MR-G, acceptance of the final version: all authors.
Funding This study has been supported by the EPoS (Elucidating Pathways of Steatohepatitis) consortium funded by the Horizon 2020 Framework Program of the European Union under Grant Agreement 634413 and the Newcastle NIHR Biomedical Research Centre. The authors are contributing members of The European NAFLD Registry. The study was also supported by the Italian Ministry of Health, grant RF-2016-02364358 (Ricerca Finalizzata, Ministero della Salute). ME and JG are supported by the Robert W. Storr Bequest to the Sydney Medical Foundation, University of Sydney; a National Health and Medical Research Council of Australia (NHMRC) Program Grant (APP1053206, APP1149976) and Project grants (APP1107178 and APP1108422).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by appropriate regulatory bodies at all participating centres.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request. N/A—No clinical trials.
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