Survival analysis and competing risk models of hospital length of stay and discharge destination: the effect of distributional assumptions

  • Carla Sá
  • Clara E. Dismuke
  • Paulo Guimarães


The literature on length of stay and hospital discharge is often used to inform policy regarding hospital payment and quality. This literature has evolved from the use of ordinary least squares estimation of linear and log-linear models to the use of survival and competing risk models that control for unobserved patient and hospital heterogeneity. However, the authors tend to adopt different distributional assumptions and often motivate the choice of specific functional forms for the baseline hazard based on the visual inspection of the hazard rate plots. We contribute to this literature by showing that parameter estimates for patient and hospital characteristics in length of stay models are particularly sensitive to underlying assumptions regarding the hazard function. Moreover, we demonstrate that the inability to distinguish between competing risks of discharge destination may lead to distortions in the effect of important explanatory variables such as intensive care utilization.


Outcomes Hazard functions Unobserved heterogeneity 

JEL Classification




The first two authors gratefully acknowledge financial support by the Portuguese Foundation for Science and Technology (FCT; refs. SFRH/BD/5054/2001; POCT/ECO/34666/2000). This revised version has benefited considerably from comments from the editor and two anonymous referees.


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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Carla Sá
    • 1
  • Clara E. Dismuke
    • 2
  • Paulo Guimarães
    • 3
  1. 1.Department of Economics and NIPEUniversidade do MinhoBragaPortugal
  2. 2.Department of Health Administration and Policy and CHEPSMedical University of South CarolinaCharlestonUSA
  3. 3.Division of ResearchMoore School of BusinessColumbiaUSA

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