Estimating surgical volume—outcome relationships applying survival models: accounting for frailty and hospital fixed effects
研究了1991-1993年间魁北克髋部骨折手术量与患者结局的关系，发现高手术量医院有更好的出院率，但这一差异源于医院间的固定质量差异，而非医院内部手术量变化带来的改善。
This paper investigates the surgical volume-outcome relationship for patients undergoing hip fracture surgery in Quebec between 1991 and 1993. Using a duration model with multiple destinations which accounts for observed and unobserved (by the researcher) patient characteristics, our initial estimates show that higher surgical volume is associated with a higher conditional probability of live discharge from the hospital. However, these results reflect differences between hospitals rather than differences within hospitals over time: when we also control for differences between hospitals that are fixed over time, hospitals performing more surgeries in period t + 1 than in period t experience no significant change in outcomes, as would be predicted by the 'practice makes perfect' hypothesis. The volume-outcome relationship for hip fracture patients thus appears to reflect quality differences between high and low volume hospitals.