Clinical utility of a diagnostic test depends on its diagnostic accuracy, the pretest probability of disease and the clinical consequences of the test results. Tools for evaluating clinical utility are scarce. We propose a new clinical utility index (CUI), which is the expected gain in utility (EGU) of the test divided by the EGU of an ideal test, both adjusted for EGU of the optimal clinical action without testing. The index expresses the relative benefit of using the test compared to using an optimal test when making a clinical decision. To illustrate how the index may be used, we estimated CUI for fasting glucose, both as a continuous and as a dichotomous test, at several values of pretest probability of diabetes mellitus and at two levels of cost/benefit-ratio. In the same clinical situations we also estimated CUI for the 2 h glucose tolerance test. Hemoglobin A1c ≥ 48 mmol/mol was used as a reference standard for diabetes mellitus. In this model, fasting glucose was clinically more useful as a continuous test than as a dichotomous one, based on CUIs. At pretest probability above the treatment threshold, fasting glucose as a continuous test was even more useful than the complete glucose tolerance test. These results are not necessarily generalizable; however, they show how the CUI can be used to select the most useful test in certain clinical situations.

诊断测试的临床效用取决于其诊断准确性，疾病的预测试概率以及测试结果的临床后果。缺乏评估临床效用的工具。我们提出了一个新的临床效用指数（CUI），即该测试的预期效用（EGU）除以理想测试的EGU，两者均针对未经测试的最佳临床作用的EGU进行了调整。该指数表示在做出临床决策时与使用最佳测试相比使用测试的相对优势。为了说明如何使用该指数，我们以空腹血糖的连续和二分法估计糖尿病的CUI，以糖尿病的预测概率的几个值和成本/收益率的两个水平进行估算。在相同的临床情况下，我们还估算了2小时葡萄糖耐量试验的CUI。血红蛋白A1c≥48 mmol / mol被用作糖尿病的参考标准。在这种模型中，基于CUI，空腹血糖在临床上作为连续测试比作为二分法更有用。在测试前概率高于治疗阈值的情况下，空腹血糖连续测试甚至比完全葡萄糖耐量测试更有用。这些结果不一定可以推广。但是，它们显示了在某些临床情况下如何使用CUI选择最有用的测试。在测试前概率高于治疗阈值的情况下，空腹血糖连续测试甚至比完全葡萄糖耐量测试更有用。这些结果不一定可以推广。但是，它们显示了在某些临床情况下如何使用CUI选择最有用的测试。在测试前概率高于治疗阈值的情况下，空腹血糖连续测试甚至比完全葡萄糖耐量测试更有用。这些结果不一定可以推广。但是，它们显示了在某些临床情况下如何使用CUI选择最有用的测试。