Detilleux Johann C
Department of Animal Production, Faculty of Veterinary Medicine, Liège University, Boulevard de Colonster, 4000 Liège, Belgium.
Vet Res. 2004 Nov-Dec;35(6):617-24. doi: 10.1051/vetres:2004042.
This paper introduces javelin diagrams as an innovative way for depicting the results of medical decision analyses. The methods were used to determine whether, and at which values, blood lactate in Belgian White and Blue or maximum tidal volumes in Holstein calves should be measured before deciding to treat or not a calf suffering from the bovine respiratory disease complex. The different alternatives depended upon the probabilities of survival with and without treatment and upon the costs associated with a possible death, the test and the treatment. The chosen alternative was the one with the lowest expected costs. From data collected on the treated calves, the expected costs of measuring lactate (198.01 euro) and tidal volumes (27.38 euro) before deciding to treat or not were lower than the expected costs of directly treating sick Belgian Blue (215.39 euro) and Holstein (51.55 euro) calves, respectively. The treatment should be applied to sick Belgian Blue calves with blood lactate < or = 7.8 mmol/L and to Holstein calves with a maximum tidal volume > or = 1.81 L. At such test values, the treatment expected costs were lower than the expected costs associated with no treatment of calves with other test values. Probabilistic sensitivity analyses showing benefits in treating animals with a positive test (over not treating the animals with a negative test) were mostly invariant to changes in any cost value but were sensitive to uncertainties in probabilities of survival with or without treatment. The javelin diagrams provided a clear visual indication of such results. They depicted how and by how much the benefits were affected by uncertainties in probabilities, they proposed different information values associated with the chosen alternative, and identified directions for further research.
本文介绍了标枪图，它是一种描绘医学决策分析结果的创新方法。该方法用于确定在决定是否治疗患有牛呼吸道疾病综合征的犊牛之前，对比利时白蓝牛的血乳酸或荷斯坦犊牛的最大潮气量应在何种值进行测量。不同的选择取决于治疗和不治疗情况下的存活概率以及与可能的死亡、检测和治疗相关的成本。所选的选择是预期成本最低的那个。根据对治疗犊牛收集的数据，在决定是否治疗之前测量乳酸（198.01欧元）和潮气量（27.38欧元）的预期成本分别低于直接治疗患病比利时蓝牛犊（215.39欧元）和荷斯坦犊牛（51.55欧元）的预期成本。对于血乳酸≤7.8 mmol/L的患病比利时蓝牛犊和最大潮气量≥1.81 L的荷斯坦犊牛应进行治疗。在这些检测值下，治疗的预期成本低于对具有其他检测值的犊牛不进行治疗的预期成本。概率敏感性分析表明，对检测呈阳性的动物进行治疗（相对于对检测呈阴性的动物不进行治疗）的益处大多不受任何成本值变化的影响，但对治疗和不治疗情况下存活概率的不确定性敏感。标枪图清晰直观地展示了这些结果。它们描绘了益处如何以及在多大程度上受到概率不确定性的影响，提出了与所选选择相关的不同信息值，并确定了进一步研究的方向。
