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Table 2 Diagnostic value of clinical examination variables in relation to single anaesthetic zygapophysial joint block

From: Zygapophysial joint blocks in chronic low back pain: a test of Revel's model as a screening test

Reference Standard A (75% reduction in Pain VAS)  
N = 116 1 Contingency table  
   Injection result  
   Positive Negative  
Criteria satisfied 3 8  
Criteria not satisfied 24 81  
% Sn 3 (95 CI8) % Sp 4 (95 CI) % PPV 5 (95 CI) % NPV 6 (95 CI) + LR 7 (95 CI)
11.1 (3.9,28.1) 91.0 (83.3,95.4) 27.3 (9.8,56.6) 77.1 (68.2,84.1) 1.2 (0.3,4.3)
Reference Standard B (Abolition of Primary Pain)  
N = 111 2 Contingency table  
   Injection result  
   Positive Negative  
Criteria satisfied 3 6  
Criteria not satisfied 15 84  
% Sn (95 CI) % Sp (95 CI) % PPV (95 CI) % NPV (95 CI) + LR (95 CI)
16.7 (5.8,39.2) 93.3 (86.2,96.9) 33.3 (12.1,64.6) 84.9 (76.5,90.6) 2.5 (0.7,9.1)
  1. Notes: 1n = 116. One case with missing data items. Unable to determine satisfaction of criteria
  2. 2n = 111. Cases with available data on abolition of primary pain
  3. 3Sn = sensitivity, Sp4 = specificity, PPV5 = positive predictive value, NPV6 = negative predictive value, +LR7 = positive likelihood ratio, 95 CI8 = 95% confidence interval