Diagnostic accuracy of speed bumps in acute appendicitis
Project Leader: Dr Helen Ashdown, Academic Clinical Fellow
During her Foundation Year 1 post in General Surgery, Helen and her colleagues noticed that some surgeons would ask patients about pain on the journey to hospital to help diagnose appendicitis, and were more likely to take a patient to theatre if they complained of increased pain over the speed bumps. They could not find any evidence base for this, and so they set up a study to investigate.
They asked all patients who had been referred to the surgical team with possible appendicitis about their journey, and then followed them through their admission to see whether they had histologically-confirmed appendicitis. They recruited 101 patients, 64 of whom thought they had travelled over speed bumps on the way into hospital. Of these, 34 had a confirmed diagnosis of appendicitis, 33 of whom reported increased pain over speed bumps. This gave a sensitivity of 97% (95% CI 85-100%) and a specificity of 30% (95% CI 15-49%) and compared favourably with other more commonly used diagnostic features, such as migratory pain or rebound tenderness.
This has the potential to change practice in that they showed that speed bumps are a good diagnostic test for appendicitis, but the high sensitivity and low specificity means that it’s a much better ‘rule out’ than ‘rule in’ test. So, if a patient has been over speed bumps and not had increased pain, it’s very unlikely they have appendicitis, but if they have had increased pain, it certainly doesn’t guarantee a diagnosis of appendicitis.
This research was published in the 2012 Christmas edition of the BMJ.