Metnitz Barbara, Metnitz Philipp G H, Bauer Peter, Valentin Andreas
Department of Medical Statistics, Medical University of Vienna, Vienna, Austria.
Wien Klin Wochenschr. 2009;121(1-2):34-40. doi: 10.1007/s00508-008-1019-0.
A positive relationship between patient volume and outcome has been demonstrated for a variety of clinical conditions and procedures, but the evidence is sparse for critically ill patients.
To evaluate the relationship between patient volume and outcome in a large cohort of critically ill patients.
Prospective multicenter cohort study, January 1998 through December 2005.
40 intensive care units in Austria.
A total of 83,259 consecutively admitted patients.
Structural quality of participating ICUs was evaluated using a questionnaire and merged with the prospectively collected data. Volume related indices were then calculated, representing patient turnover, occupancy rate, nursing workload and diagnostic variability.
Univariate analysis revealed that several volume variables were associated with outcome: more patients treated per year per bed in the intensive care unit and more patients treated in the same diagnostic category reduced the risk of dying in the hospital (odds ratios, 0.967 and 0.991 for each additional 10 patients treated, respectively). In contrast, an increase in the patient-to-nurse ratio and an increase in the number of diagnostic categories were associated with increased mortality rates. Multivariate analysis confirmed these results. The relationship between the number of patients treated in the same diagnostic category and their outcomes showed not a linear but a U shape, with increasing mortality rates below and above a certain patient volume.
Our results provide evidence for a relationship between patient volume and outcome in critically ill patients. Besides the total number of patients, diagnostic variability plays an important role. The relationship between volume and outcome seems, however, to be complex and to be influenced by other variables, such as workload of nursing staff.
已证明患者数量与多种临床病症及手术的治疗结果之间存在正相关关系，但针对重症患者的相关证据却很稀少。
评估一大群重症患者的患者数量与治疗结果之间的关系。
1998年1月至2005年12月的前瞻性多中心队列研究。
奥地利的40个重症监护病房。
总共83259名连续入院患者。
使用问卷评估参与研究的重症监护病房的结构质量，并将其与前瞻性收集的数据合并。然后计算与容量相关的指标，包括患者周转率、占用率、护理工作量和诊断变异性。
单因素分析显示，几个容量变量与治疗结果相关：重症监护病房每张床位每年治疗的患者越多，以及同一诊断类别中治疗的患者越多，住院死亡风险越低（每多治疗10名患者，优势比分别为0.967和0.991）。相比之下，患者与护士比例的增加以及诊断类别数量的增加与死亡率上升相关。多因素分析证实了这些结果。同一诊断类别中治疗的患者数量与其治疗结果之间的关系并非呈线性，而是呈U形曲线，在一定患者数量之下和之上死亡率均会上升。
我们的结果为重症患者的患者数量与治疗结果之间的关系提供了证据。除患者总数外，诊断变异性也起着重要作用。然而，容量与治疗结果之间的关系似乎很复杂，且会受到其他变量的影响，如护理人员的工作量。
