RT Journal Article
SR Electronic
T1 C reactive protein, erythrocyte sedimentation rate, or both, in the diagnosis of atraumatic paediatric limb pain?
JF Emergency Medicine Journal
JO Emerg Med J
FD BMJ Publishing Group Ltd and the British Association for Accident & Emergency Medicine
SP 969
OP 971
DO 10.1136/emermed-2011-201037
VO 29
IS 12
A1 Sara Robinson
A1 Paul Leonard
YR 2012
UL http://emj.bmj.com/content/29/12/969.abstract
AB Objective To assess if measurement of either C reactive protein (CRP) or erythrocyte sedimentation rate (ESR) individually has an equivalent diagnostic value to measurement of both in identifying orthopaedic infection as the cause of paediatric atraumatic limb pain. Setting Emergency department of a paediatric teaching hospital. Study design Retrospective study of case notes for patients attending the emergency department with a complaint of atraumatic limb pain and in whom both ESR and CRP were measured at the time of presentation. Laboratory results at the time of presentation were recorded along with the final diagnosis. Receiver operating characteristic (ROC) curves were created using the data and the optimum cut-off values for each of ESR and CRP were derived using the point of best trade off between sensitivity and specificity. Likelihood ratios for ESR and CRP individually and in combination were calculated. Results 259 patients were included in the study, of whom 17 were considered to have an orthopaedic infection. ROC curves revealed the best results were obtained using cut-off values of CRP >7 and ESR >12. The combination of a CRP >7 and an ESR >12 gave the best positive likelihood ratio at 6.26 (likelihood ratio 5.34 (CRP >7) vs 2.57 (ESR >12)). For ruling out disease, the combination of CRP ≤7 and ESR ≤12 also outperformed either variable individually (negative likelihood ratio 0.09 (CRP ≤7 and ESR ≤12) vs 0.34 (CRP ≤7) vs 0.18 (ESR ≤12)). Conclusion Measurement of both CRP and ESR should be considered an important aid in the investigation of atraumatic limb pain.