Inequality in population accessibility to automated external defibrillators under temporal availability constraints

Background Population access to automated external defibrillators (AEDs) depends on where devices are located, whether they are available when needed, and how equally accessibility is distributed across the population. Many AEDs are inaccessible outside business hours, meaning assessments based on all registered devices may overstate accessibility and obscure how unequally it is distributed. This study examined how AED accessibility and equality in accessibility are distributed across the Swiss population, and how both change when analysis is restricted to continuously available devices. Methods Population-weighted walking distance from each inhabited 100 m x 100 m grid cell to the nearest AED was calculated along the national pedestrian network under two scenarios: All-AEDs and 24h-AEDs, restricted to continuously available devices. Accessibility and equality were assessed nationally and across the 26 Swiss cantons using population-weighted mean and median walking distance, distance strata, Lorenz curves, and Gini coefficients. Results Of 15,786 registered AEDs, 6,267 (39.7%) were continuously available. Restricting analysis to 24h-AEDs increased mean walking distance from 408 m to 524 m, increased median distance from 386 m to 640 m, and nearly doubled the proportion of residents located 700 m or more from an AED, from 23.8% to 46.1%. Measured inequality decreased (Gini 0.313 vs 0.211), reflecting widespread loss of short-range accessibility rather than improved protection. Cantonal analyses revealed distinct profiles of accessibility and equality under each scenario. Conclusions More equal accessibility does not necessarily indicate better population protection. Planning and governance of AED infrastructure should address availability, accessibility, and equality together, particularly in decentralized systems with marked regional variation.