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    Reply: | American Journal of Neuroradiology  
    


















    


























    
  
  




    
    

  

      


    

      

  
  
  

    

  

    

  

                
    

      

  

    

  
      
  
  

    


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ReplyREPLY:

  
      

  
      
Reply:
  
    	
Christian Heitkamp and Christian Thaler

  
    	
American Journal of Neuroradiology June 2024,  45 (6) E15; DOI: https://doi.org/10.3174/ajnr.A8310 

  
  
  



  


  
  



  
      
  
  

    
We appreciate the interest of Mr Sabour in our study and his knowledgeable comments regarding our article recently published in the American Journal of Neuroradiology.1 We are grateful for the opportunity to address his concerns.⇓
As correctly pointed out by Mr Sabour, we used the Cohen κ to assess interrater reliability between 2 raters with categoric ratings (treatment yes/no), while the Fleiss κ was used to calculate the agreement for all 3 raters (refer to Supplementary Figure 2). The dependence of κ coefficients on prevalence has been frequently criticized and discussed;2 however, the relevance remains controversial.3,4 In the selection of methodologic and statistical test procedures, we referred to previous studies on interrater reliability in patients with vasospasm to ensure sound comparability and coherence.5,6 For the sake of clarity, we concur that a prevalence-adjusted and bias-adjusted interrater analysis may provide additional value. Please see below the prevalence-adjusted and bias-adjusted κ coefficients regarding the detection of severe vasospasm in any arterial segment (>50% narrowing), endovascular treatment decision, and the presence of a perfusion deficit (Table). The results before and after adjustment for prevalence and bias were very similar, leaving the clinical implications of our study unchanged. These findings are also in line with the standards applied in most clinics.
Interrater Reliability (95% CI)
All Raters (n = 3)Senior (n = 2)
First rating (CTA)
 Detection of severe vasospasm in any arterial segment (>50% narrowing)0.27 (0.11–0.42) 0.27 (0.11–0.43)a0.28 (0.10–0.46) 0.21 (−0.02–0.44)a
 Endovascular treatment?0.23 (0.06–0.39) 0.23 (0.07–0.39)a0.23 (−0.01–0.46) 0.23 (−0.01–0.46)a
Second rating (CTA + CTP)
 Detection of severe vasospasm in any arterial segment (>50% narrowing)0.31 (0.15–0.46) 0.31 (0.15–0.46)a0.46 (0.26–0.66) 0.46 (0.25–0.68)a
 Endovascular treatment?0.47 (0.30–0.64) 0.50 (0.35–0.66)a0.73 (0.55–0.91) 0.77 (0.62–0.93)a
 Perfusion deficit?0.77 (0.63–0.91) 0.83 (0.73–0.94)a0.82 (0.66–0.97) 0.86 (0.74–0.98)a
  • a Prevalence-adjusted and bias-adjusted κ coefficients. Note that the values were highly comparable with the results presented in the published article.
Interrater reliability regarding graduation and treatment decisions of vasospasm on CT
References
  1. 1.
    1. Heitkamp  C, 
    2. Geest  V, 
    3. Tokareva  B, et al
    . CTA supplemented by CTP increases interrater reliability and endovascular treatment use in patients with aneurysmal SAH. AJNR Am J Neuroradiol 2024;45:284–90 doi:10.3174/ajnr.A8110 pmid:38238090
  2. 2.
    1. Hallgren  KA
    . Computing inter-rater reliability for observational data: an overview and tutorial. Tutor Quant Methods Psychol 2012;8:23–34 doi:10.20982/tqmp.08.1.p023 pmid:22833776
  3. 3.
    1. Kottner  J, 
    2. Audigé  L, 
    3. Brorson  S, et al
    . Guidelines for Reporting Reliability and Agreement Studies (GRRAS) were proposed. J Clin Epidemiol 2011;64:96–106 doi:10.1016/j.jclinepi.2010.03.002 pmid:21130355
  4. 4.
    1. Vach  W
    . The dependence of Cohen’s kappa on the prevalence does not matter. J Clin Epidemiol 2005;58:655–61 doi:10.1016/j.jclinepi.2004.02.021 pmid:15939215
  5. 5.
    1. Darsaut  TE, 
    2. Derksen  C, 
    3. Farzin  B, et al
    . Reliability of the diagnosis of cerebral vasospasm using catheter cerebral angiography: a systematic review and inter- and intraobserver study. AJNR Am J Neuroradiol 2021;42:501–07 doi:10.3174/ajnr.A7021 pmid:33509923
  6. 6.
    1. Letourneau-Guillon  L, 
    2. Farzin  B, 
    3. Darsaut  TE, et al
    . Reliability of CT angiography in cerebral vasospasm: a systematic review of the literature and an inter- and intraobserver study. AJNR Am J Neuroradiol 2020;41:612–18 doi:10.3174/ajnr.A6462 pmid:32217551
  


  
  



  



    

  



  

                
    

      

  

    

  
      
  
  

    


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