Hospital pressure and length of stay under organisational reform: evidence from Portuguese public hospitals

Purpose This study examines how inpatient occupancy pressure and organisational reform are associated with average length of stay (LOS) in Portuguese public hospitals. Design/methodology/approach The analysis uses a monthly hospital-level panel dataset for Portuguese public hospitals covering 2015–2025. A dynamic fixed-effects model is estimated to account for persistence in hospital performance, time-invariant hospital heterogeneity and common time shocks. Hospital activity pressure is measured using the reported inpatient occupancy rate, with emergency activity included as an additional demand-side pressure indicator in robustness specifications. Findings The results show strong persistence in hospital length of stay, indicating that organisational patterns are associated with hospital performance over time. Inpatient occupancy pressure is positively associated with length of stay, a pattern consistent with capacity saturation and congestion. The reform indicator is not statistically significant after controlling for persistence, hospital capacity, hospital fixed effects and time effects. Additional interaction models do not provide robust evidence that the occupancy–LOS association differs by reform exposure, hospital size or the post-2024 period. Originality/value The study conceptualises LOS as a dynamic organisational outcome and offers hospital-month evidence from the Portuguese public hospital system on the association between capacity pressure, organisational reform and inpatient stay duration.