Journal Club Summaryshoulder

Methodology Score: 3.5/5                
Usefulness Score:  2.5/5
Hermans J, et al. JAMA. 2013 Aug 28;310(8):837-47.
This systematic review of studies comparing clinical tests for rotator cuff disease with a diagnostic reference standard of MRI or U/S found that positive tests of internal rotation lag ((+)LR 5.6, 95% CI 2.6 – 12), external rotation lag (LR 7.2, 95% CI 1.7 – 31), and the painful arc ((+)LR 3.7, 95% CI 1.9 – 7.0) have the highest positive likelihood ratios for rotator cuff disease. JC attendees agreed that the question is useful, but that the studies included in this systematic review lacked reproducibility and generalizability to an emergency department population, and that their large 95% CI’s preclude the utility of these results in changing our daily practice.                                                         
By: Dr. Laura Francis

Epi lesson: Verification Bias

When critically appraising a study evaluating a diagnostic test, it is important to examine the study population closely. In emergency medicine, we see undifferentiated patients the majority of the time. Studies of specialist referral populations have less generalizability to the ED because inherently the diagnostic test will perform better in a population with a high pre-test probability of disease in the first place. Verification bias, or work-up bias, applies here where the likelihood of performing the gold standard is influenced by the results of the diagnostic test under study. In this case, performing MRI or U/S for rotator cuff disease is influenced by the results of the physical examination tests being studied.
By: Dr. Lisa Calder