Hip fracture or not? The reversed prevalence effect among non-experts' diagnosis.

Despite numerous investigations of the prevalence effect on medical image perception, little research has been done to examine the effect of expertise, and its possible interaction with prevalence. In this study, medical practitioners were instructed to detect the presence of hip fracture in 50 X-ray images with either high prevalence (Nsignal = 40) or low prevalence (Nsignal = 10). Results showed that compared to novices (e.g., pediatricians, dentists, neurologists), the manipulation of prevalence shifted participant's criteria in a different direction for experts who perform hip fracture diagnosis on a daily basis. That is, when prevalence rate is low (pfracture-present = 0.2), experts held more conservative criteria in answering "fracture-present," whereas novices were more likely to believe there was fracture. Importantly, participants' detection discriminability did not vary by the prevalence condition. In addition, all participants were more conservative with "fracture-present" responses when task difficulty increased. We suspect the apparent opposite criteria shift between experts and novices may have come from medical training that made novices to believe that a miss would result in larger cost compared to false positive, or because they failed to update their prior belief about the signal prevalence in the task, both would suggest that novices and experts may have different beliefs in placing the optimal strategy in the hip fracture diagnosis. Our work can contribute to medical education training as well as other applied clinical diagnosis that aims to mitigate the prevalence effect.

Loss of skeletal muscle mass can be predicted by sarcopenia and reflects poor functional recovery at one year after surgery for geriatric hip fractures.

INTRODUCTION: Hip fractures in the elderly impact negatively on functional dependence, and carry great social costs and morbidity. We assessed the decline in muscle mass and functional outcomes following hip fracture surgery . MATERIAL AND METHODS: Thirty patients with a hip fracture (mean age: 80.8 years) were assessed using dual-energy X-ray absorptiometry and reassessed for changes in body composition 1 year after hip surgery. Baseline demographic data, sarcopenia, and bone mineral density were recorded. Body mass index (BMI), handgrip strength, appendicular skeletal muscle mass (ASM), total body fat percentage, and responses to questionnaires measuring quality of life and activities of daily living (ADL) before injury and 1 year after hip surgery were analyzed to identify changes. Associations with changes in ADL or quality of life were analyzed with time-variant independent variables. RESULTS: Significant losses in ADL were identified at the 1-year follow-up, at which time only 43% of patients had regained their preinjury ADL status. Additionally, the participants had lost an average of 4.63% of ASM. ASM loss was significantly higher in patients with baseline sarcopenia than in those without (mean loss: 9.18% and 1.15%, respectively). When confounders were controlled for, a greater loss of ASM and handgrip strength and larger increase in BMI were associated with greater decrease in ADL 1 year after hip surgery. CONCLUSION: Geriatric hip fracture patients may experience a significant loss of muscle mass, associated with impaired functional recovery 1 year after hip surgery, highlighting a potential treatment target of maintaining muscle mass to improve prognosis in these patients.