National Inpatient Sample

The NIS includes roughly 20% of hospitalisations from participating hospitals and uses weighting to estimate national totals. The study used NIS data from 2015 to 2021. The NIS is the largest publicly available all-payer inpatient database in the United States. The NIS does not contain detailed clinical data such as laboratory values, imaging, or liver biopsy results, limiting the study's analytical depth. The use of a large, nationally representative administrative database improves the generalisability of the findings. The retrospective design of the study prevents causal inference.