QUANTITATIVE ASSESSMENTS FROM THE CLINICAL EXAMINATION - HOW SHOULD CLINICIAN INTEGRATE THE NUMEROUS RESULTS

OBJECTIVE: To describe strategies for using multiple clinical examinat ion items to estimate disease probabilities; and to evaluate the diagn ostic accuracy of each strategy. DESIGN Prospective observational stud y. SETTING: Medical preoperative evaluation clinic at a university-aff iliated Veterans Affairs Medical Center. PATIENTS: Previously reported consecutive series of patients referred for outpatient medical preope rative risk assessment. MEASUREMENTS AND MAIN RESULTS: Pulmonary clini cal examination and spirometry were the measurements. A strategy of us ing likelihood ratios (LRs) from seven clinical examination items was least accurate (p < .0001). Three alternative strategies were equivale nt in diagnostic accuracy (p greater than or equal to .2): (1) using t he 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 wit h using LRs from all seven items, the strategies of using three LRs ch osen by logistic regression or using adjusted likelihood ratios better discriminated patients with airflow limitation from those without (re ceiver operating characteristic [ROC] areas 0.79 vs 0.69: p = .02). Us ing the single best clinical finding did not statistically degrade the clinical examination's discriminating ability (ROC areas 0.79 vs 0.75 ; p = .20). CONCLUSIONS: Describing the rational clinical examination requires evaluating conditional independence of examination components . Conditional independence assumptions were violated when seven clinic al examination items were used to estimate posterior probability of ai rflow limitation. Focusing on clinical examination items identified th rough logistic models overcame violations of independence; further sta tistical adjustment did not improve diagnostic accuracy. Clinicians ca n use the single most predictive clinical examination finding to avoid inaccuracy from violating the independence assumption.