Holleman D R, Simel D L
Medical Service, Lexington Veterans Affairs Medical Center, KY 40511, USA.
J Gen Intern Med. 1997 Mar;12(3):165-71. doi: 10.1007/s11606-006-5024-6.
To describe strategies for using multiple clinical examination items to estimate disease probabilities; and to evaluate the diagnostic accuracy of each strategy.
Prospective observational study.
Medical preoperative evaluation clinic at a university-affiliated Veterans Affairs Medical Center.
Previously reported consecutive series of patients referred for outpatient medical preoperative risk assessment.
Pulmonary clinical examination and spirometry were the measurements. A strategy of using likelihood ratios (LRs) from seven clinical examination items was least accurate (p < .0001). Three alternative strategies were equivalent in diagnostic accuracy (p > or = .2): (1) using the single best clinical examination item and its LR, (2) using the LRs from three clinical examination items chosen by logistic regression, and (3) using the adjusted LRs chosen in strategy 2. When compared with using LRs from all seven items, the strategies of using three LRs chosen by logistic regression or using adjusted likelihood ratios better discriminated patients with airflow limitation from those without (receiver operating characteristic [ROC] areas 0.79 vs 0.69; p = .02). Using the single best clinical finding did not statistically degrade the clinical examination's discriminating ability (ROC areas 0.79 vs 0.75; p = .20).
Describing the rational clinical examination requires evaluating conditional independence of examination components. Conditional independence assumptions were violated when seven clinical examination items were used to estimate posterior probability of airflow limitation. Focusing on clinical examination items identified through logistic models overcame violations of independence; further statistical adjustment did not improve diagnostic accuracy. Clinicians can use the single most predictive clinical examination finding to avoid inaccuracy from violating the independence assumption.
描述使用多个临床检查项目来估计疾病概率的策略；并评估每种策略的诊断准确性。
前瞻性观察性研究。
一所大学附属退伍军人事务医疗中心的术前医学评估诊所。
先前报告的连续系列因门诊术前医学风险评估而转诊的患者。
测量项目为肺部临床检查和肺功能测定。使用来自七个临床检查项目的似然比（LRs）的策略准确性最低（p < 0.0001）。三种替代策略在诊断准确性方面相当（p ≥ 0.2）：（1）使用单个最佳临床检查项目及其LR，（2）使用通过逻辑回归选择的三个临床检查项目的LR，以及（3）使用在策略2中选择的调整后的LR。与使用所有七个项目的LR相比，通过逻辑回归选择三个LR或使用调整后的似然比的策略能更好地区分有气流受限的患者和无气流受限的患者（受试者操作特征曲线[ROC]面积分别为0.79对0.69；p = 0.02）。使用单个最佳临床发现并未在统计学上降低临床检查的鉴别能力（ROC面积分别为0.79对0.75；p = 0.20）。
描述合理的临床检查需要评估检查组成部分的条件独立性。当使用七个临床检查项目来估计气流受限的后验概率时，条件独立性假设被违反。关注通过逻辑模型确定的临床检查项目克服了独立性的违反；进一步的统计调整并未提高诊断准确性。临床医生可以使用最具预测性的单个临床检查发现来避免因违反独立性假设而导致的不准确。
