[Algorithm for establishing hospital admittance data based on the hospital information system in the Brazilian Unified Health System]

The authorization form for hospital admittance (AIH), an observation unit under the Hospital Information System of the Unified Health System (SIH/SUS), may represent a short-term hospital admittance or a longer hospital stay. This study presents an algorithm for composing admittance data based on the AIH forms, allowing for a proper assessment of hospital mortality, costs under the Unified Health System (SUS), and longer hospital stays, typical of chronic, terminal, and psychiatric patients.