Some Problems Arising in the Statistical Treatment of Diagnosis

Upper gastrointestinal tract bleeding: assessing the diagnostic contributions of the history and clinical findings

Various strategies can be used in the diagnosis of upper gastrointestinal tract bleeding. This study investigates the relevance of anamnestic and clinical findings for the diagnosis of the bleeding source. The authors introduced a computer-aided diagnostic system using Bayes' theorem and compared it with clinicians' predictions using anamnestic and clinical findings only. There was no difference in the overall accuracy rates, but a difference was observed in the diagnostic behaviors of the two "systems." In addition, the discriminatory ability of the computer-aided system, the sharpness of the predictions obtained, and the reliability of the posterior probabilities were analyzed. It is concluded that the clinician and the computer-aided system are not able to discriminate well between the disease categories. Derived classification matrices and probability-based measures show the reasons for the inadequacy of diagnostic information obtainable from the clinical history and physical findings.

Inspection-palpation-percussion-auscultation and an outcome-oriented alternative approach to the musculoskeletal examination

Thirty-two university-based doctors and sixty-seven medical students used a visual analogue scale (VAS) to estimate the usefulness of the inspection-palpation-percussion-auscultation (IPPA) approach. Doctors considered IPPA less useful in the examination of the musculoskeletal system than in other systems, both in clinical practice (P less than 0.01) and as an aid in teaching (P less than 0.01). Students rated IPPA less useful in the musculoskeletal examination than in other systems as a learning aid (P less than 0.001). Based on these findings, an alternative model for physical examination of the musculoskeletal system was devised, using inspection, palpation and other clinical methods only when required to reach a diagnosis. The model focused on the outcome of the diagnostic process (aetiological, anatomical/pathophysiological and functional diagnoses) rather than on the process itself. Thirteen students taught this method found it a useful learning aid. Those familiar with both methods preferred the outcome-oriented to the IPPA method (P less than 0.001).