Satisfaction of search in multitrauma patients: severity of detected fractures

Abstract

Rationale and objectives: Satisfaction of search (SOS) occurs when an abnormality is missed because another abnormality has been detected. This research studied whether the severity of a detected fracture determines whether subsequent fractures are overlooked.

Materials and methods: Each of 70 simulated multitrauma patients presented examinations of three anatomic areas. Readers evaluated each patient under two experimental conditions: when the images of the first anatomic area included a fracture (the SOS condition), and when it did not (the control condition). The SOS effect was measured on detection accuracy for subtle test fractures presented on examinations of the second and third anatomic areas. In an experiment with 12 radiology readers, the initial SOS radiographs showed nondisplaced fractures of extremities, fractures associated with low morbidity. In another experiment with 12 different radiology readers, the initial examination, usually a computed tomography scan, showed cervical and pelvic fractures of the type associated with high morbidity. Because of their more direct role in patient care, the experiment using high morbidity SOS fractures was repeated with 17 orthopedic readers.

Results: Detection of subtle test fractures was substantially reduced when fractures of low morbidity were added (P < .01). No similar SOS effect was observed in either experiment in which added fractures were associated with high morbidity.

Conclusions: The satisfaction of search effect in skeletal radiology was replicated, essentially doubling the evidence for SOS in musculoskeletal radiology, and providing an essential contrast to the absence of SOS from high-morbidity fractures.

Figure 1

The fractures used in case 28 in different experiments and experimental conditions. A and B represent obvious abnormalities with major clinical significance (arrows) and include a C5 bilateral facet dislocation (A) with anterior translation of C5 on C6 (B). The acetabular fracture (arrow) in C represents a noticeable, but less significant abnormality. The navicular fracture (arrow), while the least obvious, is best seen on the lateral view (D), although the AP and oblique views were also presented. The navicular fracture serves as a test fracture. Its detection was measured when a fracture of major clinical significance (A and B) was present in the case and when it was not. In a separate experiment, the detection of the target fracture (D) was measured when a more obvious, though non-life threatening fracture (C) was present in the case and when it was not.

Figure 2

Case 28 as it appeared in thumbnails in: (A) the SOS condition of experiment 1; (B) the non-SOS condition of experiment 1; (C) the SOS condition of experiment 2; and (D) the non-SOS condition of experiment 1. The test fracture was a right navicular fracture visible on the foot (when shown on a 3 megapixel monitor, A–D). The chest examination was normal (A–D). The minor added fracture in experiment 1 was a left acetabular fracture (A). The corresponding pelvic study for the non-SOS condition was a normal pelvis (B). The major fracture in experiment 2 was a C6 anterior subluxation with bilateral facet fracture (C). The corresponding cervical spine CT study for the non-SOS condition was normal (D).

Figure 3

A dual-monitor display of case 28 as it appeared in experiments 2 and 3. Each case was initially presented with patient information, case number, and thumbnail images comprising the complete study on the left monitor (A). Images were displayed, one examination at a time, on the right monitor for diagnostic interpretation (B–D). In the first examination display (B), the three images are sagittal, coronal, and axial image stacks of a cervical spine CT demonstrating a C6 anterior subluxation with bilateral facet fracture. This fracture/subluxation is associated with major morbidity and served as a major added fracture. The next three images are digital radiographs of the foot demonstrating a subtle navicular fracture that served as a test fracture (C). The chest radiograph did not demonstrate a fracture (D).

Figure 4

Results of DBM MRMC analyses performed on the first experiment using contaminated binormal ROC area as the accuracy parameter (left panel) and sensitivity at specificity = 0.9 as the accuracy parameter (right panel). Each dot indicates an individual reader’s accuracy; arrows indicate mean accuracy for the two conditions. An SOS effect was demonstrated.

Figure 5

Results of DBM MRMC analyses performed on the second experiment using contaminated binormal ROC area as the accuracy parameter (left panel) and sensitivity at specificity = 0.9 as the accuracy parameter (right panel). Each dot indicates an individual reader’s accuracy; arrows indicate mean accuracy for the two conditions. No SOS effect was demonstrated.

Figure 6

Results of DBM MRMC analyses performed on the third experiment using contaminated binormal ROC area as the accuracy parameter (left panel) and sensitivity at specificity = 0.9 as the accuracy parameter (right panel). Each dot indicates an individual reader’s accuracy; arrows indicate mean accuracy for the two conditions. No SOS effect was demonstrated.