Epidemiology, temporal trends, and fibrosis risk stratification in metabolic dysfunction-associated steatotic liver disease in UK primary care: a population-based cohort and nested case-control study.

BACKGROUND: We sought to determine the changing prevalence, incidence, and temporal trends in real-world, recorded diagnoses of metabolic dysfunction-associated steatotic liver disease (MASLD) and assess availability of fibrosis risk stratification following awareness campaigns and guideline updates over the last decade. METHODS: This population-based cohort study identified MASLD diagnoses made between 2003 and 2022 in the UK primary-care Clinical Practice Research Datalink (CPRD) to estimate prevalence and incidence. A nested case-control analysis, utilising 1:4 age-, sex-, and general practice-matched controls, assessed clinical characteristics, availability of Fibrosis-4 (Fib-4) components, and its temporal trend pre- and post-2015. FINDINGS: 11.7 million individuals were active in CPRD in 2022. 365,797 comprised the study cohort of people with a MASLD diagnosis (matched to 1,460,288 controls). From 2012 to 2022, recorded MASLD prevalence rose from 0.52% [N = 51,028] to 2.42% [N = 283,762] (p < 0.001); recorded incidence doubled from 1.60 to 3.31 per 1000 person-years (p < 0.001). People with MASLD diagnosis had a higher prevalence of type 2 diabetes (21.0% [N = 76,640] vs 7.7% [N = 112,812]) and hypertension (35.3% [N = 129,156] vs 18.7% [N = 273,502]). People of South Asian ethnicity were overrepresented in MASLD cohort but had the lowest availability of Fib-4 components (14.6% [N = 4467]; adjusted odds ratio 0.67, 95% CI: 0.65-0.70, vs White). Overall, Fib-4 availability increased pre-to post-2015 (4.3% [N = 4945] to 22.8% [N = 56,634]). Among those with a calculable score, fewer South Asian individuals had indeterminate/high risk (18.6% [N = 833] vs 35.3% [N = 15,115] in White individuals, p < 0.001). INTERPRETATION: Recorded MASLD prevalence has increased 5-fold in a decade, yet a diagnostic gap persists. Fibrosis risk stratification has improved, but remains low and is potentially inequitable for people of South Asian ethnicity. FUNDING: Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA; Barts Charity.