Best Evidence Topics

Diagnosis

Appelboam A, Reuben AD, Benger JR, et. al.
Elbow extension test to rule out elbow fracture: multicentre, prospective validation and observational study of diagnostic accuracy in adults and children
British Medical Journal
2008; 337:a2428 (online)
  • Submitted by:Joshua Mastenbrook - Medical Student
  • Institution:Michigan State University
  • Date submitted:8th September 2009
Before CA, i rated this paper: 5/10
1 Objectives and hypotheses
1.1 Are the objectives of the study clearly stated?
  Yes, the authors clearly state the objective of the study to be: "To determine whether full elbow extension as assessed by the elbow extension test can be used in routine clinical practice to rule out bony injury in patients presenting with elbow injury."
2 Design
2.1 Is the study design suitable for the objectives
  The study employs a fair design for the purpose of its objective with the exception of the configuration of the gold standard used to evaluate the study participants (not all participants underwent x-ray).
2.2 Who / what was studied?
  Child (3-15 years old) and Adults (>15 years old) presenting to one of five different Emergency Departments in the UK with an acute elbow injury were recruted for the study. Exclusion criteria: Previous limited extension, Altered mental status, Multiple injuries, No consent, No history of trauma, Injury >72 hours old, neuromuscular disease, Suspicion of intentional injury, and Osteogenesis imperfecta.
2.3 Was this the right sample to answer the objectives?
  Yes, the study was intented to evaluate the need for x-ray imaging in adults and children with acute elbow injury.
2.4 Is the study large enough to achieve its objectives? Have sample size estimates been performed?
  The authors estimated they would need 300 adults and 300 children with full elbow extension and no fracture to acheive a sensitivity of 100% with 95% confidence intervals between 99%-100%. At the end, 581 adults and 275 child fullfilled these two criteria. The adult sample size was sufficient, but the child sample size was less than the authors wanted.
2.5 Were all subjects accounted for?
  All but 6 (4 adults and 2 children) study participants were accounted for at the end of the study. The total number of participants after initial exclusion criteria were applied was 1740 adults and 780 children.
2.6 Were all appropriate outcomes considered?
  The outcomes of interest were: yes/no full elbow extension and yes/no fracture. These were considered in all participants, but the possibility of a radiographically evidant elbow fracture was the confirmed in all participants (with full elbow extension).
2.7 Has ethical approval been obtained if appropriate?
  The methods section does not mention ethical approval, but this does not necessarily seem to be needed with the implemented study design.
2.8 Was an independent blinded gold standard test applied to all subjects?
  There was not an evidant blinded gold standard applied to all subjects. It would seem that if the study intended to evaluate the need for radiographic imaging for individuals presenting with acute elbow injury after using the elbow extension test, that it would be necessarily to x-ray all participants for a definitive diagnosis. Several different "reference standards" were used for individuals with full elbow extension: final discharge diagnosis if participant was seen in an orthopedic clinc, final report from a blinded radiologist in clinic was not utilized, or a telephone interview for those not seen in a clinic or imaged. The methods section does not indicate if those reading the x-ray were blinded (for participants with a positive elbow extension test).
3 Measurement and observation
3.1 Is it clear what was measured, how it was measured and what the outcomes were?
  Yes, the data gathered included number of participants with full or not full elbow extension, and the number of participants with and without a fracture. The only questions that lingers is that not all individuals with full extension were imaged and as such it is not possible to know with 100% assurance whether or not they would have had a fracture evidant on x-ray. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated from the data.
3.2 Are the measurements valid?
  The lack of a solid, blinded reference standard lend to the possibility of bias entering into the picture and therefore decreases the validity of the measurements.
3.3 Are the measurements reliable?
  The authors acknowledge that interobserver agreement was not assessed, but all healthcare providers administering the test were equally trained.
3.4 Are the measurements reproducible?
  The measurements seem to be reproducible. Similar studies were conducted by other groups, but with significantly fewer participants. However, the sensitivity from each study was similar.
4 Presentation of results
4.1 Are the basic data adequately described?
  Yes, there is a flow diagram of the results of the study, including number of participants, number exluded, number lost to follow-up, number with +/- elbow extention test results, and number of fracture/no fracture.
4.2 Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
  Yes, the reader can calculate the Sn, Sp, PPV, and NPV.
4.3 Are the results internally consistent, i.e. do the numbers add up properly?
  Yes, the data presented and the analysis (Sn, Sp, PPV, NPV) are in agreement.
5 Analysis
5.1 Are the data suitable for analysis?
  Yes, the data collected allow for the calculation of Sn, Sp, PPV, and NPV. Ninety-five percent confidance intervals and p-values were also explained and calculated appropriately.
5.2 Are the methods appropriate to the data?
  Yes, the methods are appropriate to the data (again there is some question about the validity of the methods to the "verify" no fracture of those with a negative elbow extension test).
5.3 Are any statistics correctly performed and interpreted?
  Yes, all statitics are correct.
6 Discussion
6.1 Are the results discussed in relation to existing knowledge on the subject and study objectives?
  There is limited knowledge about the use of elbow extention tests to aid in the desicion of whether or not to image a patient with an acute elbow injury. There are studies involving other joints and the authors reference this point. The authors do discuss the results in terms of the study objective.
6.2 Is the discussion biased?
  The discussion does not appear biased, but the authors do acknowledge that their original "goal" sensitivity was not met, and then go on to say, "Ninety nine per cent sensitivity is a challenging standard," perhaps implying that the test is still useful, but that "ultimately, application of this test will rely on physicians’ judgment, informed by the risk and consequences of false negatives, and by the availability of a gold standard diagnostic test (radiography) and follow-up."
7 Interpretation
7.1 Are the authors' conclusions justified by the data?
  Based on the data collected, the authors' interpretation of their data seems justified. "patients with recent elbow injury who cannot fully extend their elbow should be referred for radiography. Those who are able to fully extend do not need radiography, provided the practitioner is confident that olecranon fracture is not present, that caution is used in children, and that the patient can return for reassessment if their symptoms have not resolved in 7-10 days."
7.2 What level of evidence has this paper presented? (using CEBM levels )
  3c due to inconsistently applied reference standard. The sensitivity for adults is 98.4% (96.3-99.5) which approaches a 1c level.
7.3 Does this paper help me answer my problem?
  The problem is whether or not to image a patient with an acute elbow injury. The data presented by this study aid in the decision about imaging.
After CA, i rated this paper: 5/10
8 Implementation
8.1 Can the test be implemented in practice?
  The test appears to be a good tool in aiding the decision of whether or not to image a patient and is simple and easy to learn/impliment.
8.2 What aids to implementation exist?
  The elbow extension test is simple and easy to understand: "The seated patient, with exposed and supinated arms, is asked to flex their shoulders to 90 degrees and then fully extend and lock both elbows. Injured and uninjured sides are compared visually and those with equal extension recorded as full extension.”
8.3 What barriers to implementation exist?
  There are few barriers to implementation of this test. Users simply need to be educated on the positioning that the patient should be instructed to assume with him/her arm.
8.4 Are my patients the same as the patients tested?
  Yes, the patients appear to be similar to those of the study: individuals >3 years old presenting within 72 hours of an acute elbow injury to an Emergency Department.
8.5 Will the test improve diagnosis in my patients?
  The test itself is not a definitive diagnostic test, but appears to be a useful tool to aid in the decision of whether or not to image a patient presenting with an acute elbow injury. The test is not 100% sensitive and appears to have a statistically significant higher sensitivity in adults (>15 years old) than children (3-15 years old), and therefore might be considered more useful in the former patient population. Nevertheless, the sensitivity is still >95% in both groups, and along with clinical judgement, the elbow extension test still seems to be a good tool for aiding in the decision of whether or not to image. Future studies should apply a standard reference to all patients, perhaps x-raying all elbow injuries, which may or may not yield a higher sensitivity.