Background & aimsChronic hepatitis B (CHB) and metabolic dysfunction-associated steatotic liver disease (MASLD) commonly co-exist, with conflicting data in prevalence and disease severity. We aimed to investigate these discrepancies.MethodsThis multicenter study included consecutive patients with CHB from 19 European centers. A survey on standard of care for MASLD screening in CHB was circulated.ResultsA total of 1709 patients with CHB were included; median age, 53 years (interquartile range [IQR], 42-64); males, 60.7%; body mass index (BMI), 25.6 kg/m2 (IQR, 14-63 kg/m2); and 57.3% White. MASLD prevalence (1510 consecutive patients) was 42.3%. BMI (odds ratio [OR], 1.27; 95% confidence interval [CI], 1.19-1.36), ferritin (OR, 1.00; 95% CI, 1.00-1.00) and type 2 diabetes (OR, 2.60; 95% CI, 1.12-6.02) were independently associated with MASLD. The prevalence of advanced fibrosis was 18% (255/1420) in the whole cohort, 25.4% (162/639) among patients with CHB with MASLD, and 13.7% in those without MASLD. Independent predictors of advanced fibrosis were MASLD (OR, 2.76; 95% CI, 1.50-5.05), BMI (OR, 1.08; 95% CI, 1.02-1.15), alanine transaminase (OR, 1.01; 95% CI, 1.00-1.03), lower platelets (OR, 0.99; 95% CI, 0.98-0.99), insulin treatment (OR, 13.88; 95% CI, 2.95-65.28), and long-term antivirals (OR, 4.86; 95% CI, 2.40-9.85). During follow-up (48 months), only patients without MASLD showed significant liver stiffness measurement improvement over time (P < .001). Among patients with MASLD, Fibrosis-4 and liver stiffness measurement performed moderately at predicting advanced fibrosis (area under the receiver operating characteristic curve = 0.71 vs 0.70; P = .38) against histology. As standard of care, 68.4% of centers screened all patients with CHB for MASLD; 52.6% followed the same treatment indication in those with CHB and MASLD vs CHB only.ConclusionsIn this large European cohort, MASLD and fibrosis were highly prevalent among patients with CHB, whereas MASLD aggravated liver fibrosis. Though screening strategies remain inconsistent, ferritin levels, increased BMI, and type 2 diabetes may inform on the presence of MASLD. Biomarkers showed modest performance in predicting fibrosis.