Department of Health Care Policy, Harvard Medical School, Department of Medicine, Massachusetts General Hospital, and the National Bureau of Economic Research, Cambridge, MA (A.B.J.); Department of Anesthesia, Stanford University Hospitals, Stanford, CA (E.C.S.); and the Leonard D. Schaeffer Center for Health Policy and Economics, University of Southern California, Los Angeles, CA and RAND Corporation, Santa Monica, CA (J.A.R.).
Circulation. 2013 Dec 24;128(25):2754-63. doi: 10.1161/CIRCULATIONAHA.113.004074. Epub 2013 Oct 23.
Studies of whether inpatient mortality in US teaching hospitals rises in July as a result of organizational disruption and relative inexperience of new physicians (July effect) find small and mixed results, perhaps because study populations primarily include low-risk inpatients whose mortality outcomes are unlikely to exhibit a July effect.
Using the US Nationwide Inpatient sample, we estimated difference-in-difference models of mortality, percutaneous coronary intervention rates, and bleeding complication rates, for high- and low-risk patients with acute myocardial infarction admitted to 98 teaching-intensive and 1353 non-teaching-intensive hospitals during May and July 2002 to 2008. Among patients in the top quartile of predicted acute myocardial infarction mortality (high risk), adjusted mortality was lower in May than July in teaching-intensive hospitals (18.8% in May, 22.7% in July, P<0.01), but similar in non-teaching-intensive hospitals (22.5% in May, 22.8% in July, P=0.70). Among patients in the lowest three quartiles of predicted acute myocardial infarction mortality (low risk), adjusted mortality was similar in May and July in both teaching-intensive hospitals (2.1% in May, 1.9% in July, P=0.45) and non-teaching-intensive hospitals (2.7% in May, 2.8% in July, P=0.21). Differences in percutaneous coronary intervention and bleeding complication rates could not explain the observed July mortality effect among high risk patients.
High-risk acute myocardial infarction patients experience similar mortality in teaching- and non-teaching-intensive hospitals in July, but lower mortality in teaching-intensive hospitals in May. Low-risk patients experience no such July effect in teaching-intensive hospitals.
美国教学医院 7 月住院死亡率是否因组织混乱和新医生相对缺乏经验而上升的研究（7 月效应）得出的结果差异较小且不一致，原因可能是研究人群主要包括低危住院患者，他们的死亡率不太可能出现 7 月效应。
我们使用美国全国住院患者样本，对 2002 年至 2008 年 5 月至 7 月期间入住 98 家教学密集型和 1353 家非教学密集型医院的高危和低危急性心肌梗死患者的死亡率、经皮冠状动脉介入治疗率和出血并发症率进行了差异中的差异模型估计。在预测急性心肌梗死死亡率最高四分位数的患者（高危）中，教学密集型医院 5 月的死亡率低于 7 月（5 月 18.8%，7 月 22.7%，P<0.01），而非教学密集型医院的死亡率则相似（5 月 22.5%，7 月 22.8%，P=0.70）。在预测急性心肌梗死死亡率最低三分位数的患者（低危）中，教学密集型和非教学密集型医院 5 月和 7 月的死亡率相似（5 月 2.1%，7 月 1.9%，P=0.45）和非教学密集型医院（5 月 2.7%，7 月 2.8%，P=0.21）。经皮冠状动脉介入治疗和出血并发症率的差异无法解释高危患者观察到的 7 月死亡率效应。
高危急性心肌梗死患者在教学和非教学密集型医院 7 月的死亡率相似，但在教学密集型医院 5 月的死亡率较低。低危患者在教学密集型医院中没有这种 7 月效应。
