Diagnostic Studies Specimen Appraisal Adrian Boyle

Accuracy of Point-of-Care Ultrasonography for Diagnosis of Elbow Fractures in Children

What did they do? Population 130 Children with suspected elbow fractures Exposure (Intervention) POCT USS by trained Emergency Physicians Outcome Confirmed fracture on radiographic follow up

Appraisal What sort of study did they do? Is this externally valid? Why is this study the size it is?

Appraisal: what flaws can you see in this study? Convenience sample Single centre Little data about how the operator’s varied (did one expert perform 90% of the scans) Small sample, confidence interval width applied to BOTH sensitivity and specificity Selected sample (16 months to collect 130) Fracture prevalence is probably much higher than practice (Spectrum Bias) Follow up was only applied to those with negative x-rays BIAS

Appraisal: strengths Follow up arrangements look good, (minimal loss to follow up but look at Fig. 4, they included 4 people with no f/u) Outcome by radiologist is blinded Assessed Kappa Common problem Ethical approval

Would you do this?

Would you do this? Probably doesn’t help me much Don’t believe the bit about time Convenience samples inflate sensitivity and specificity values Not sure about the value for my practice (but GPs?) CI are very wide: Sensitivity 98 (88-100) Sensitivity is probably the most important outcome measure in this diagnostic scenario