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Table 2 Main characteristics, results and quality rating of four studies on mammography screening

From: Is single reading with computer-aided detection (CAD) as good as double reading in mammography screening? A systematic review

Author, Year (ref) Study design, Study period,Population, Readers Index test (I) Reference test Results CI= confidence interval Se= sensitivity Sp=specificity Study quality, Comments
Gilbert et al., 2008 [71] Prospective, multicentre 2006-2007 I.1: single reading + CAD, n=28,204 Biopsy of suspected cases or follow-up (not all, though; number not reported) Cancer detection rate: Moderate
     Single reading + CAD: 7.02 /1000.  
  Population:    Double reading: 7.06/1000. Restricted generalisability since results were based on single reading +CAD by experienced radiologists.
     Difference not statistically significant (NS).  
   I.2: double reading, n=28,204.    
  Initially invited: 68,060 women.     
     Recall rate: Incomplete follow-up, particularly affecting the estimates of sensitivity.
  Investigated: 28,204.     
  Aged 50-70 years (1 % > 70 years).    Single reading + CAD: 3.9 %.  
     Double reading: 3.4 %. Scanned analogue mammograms.
     Difference 0.5 % (95 % CI: 0.3;0.8).  
  Readers: radiologists (n=17), specially trained staff (n=10).     
     Single reading + CAD:  
     Se= 87.2 %  
     Sp= 96.9 %  
  All readers had at least 6 years’ experience and >5000 readings/year    Double reading:  
     Se= 87.7 %  
     Sp= 97.4 %  
     Difference in sensitivity:  
     0.5 % (95 % CI:  
     -7.4;6.6), (NS).  
     Difference in specificity 0,5% ( CI not specified but reported NS).  
Gromet et al., 2008 [69] Retrospective I.1: Single reading + CAD Biopsy and follow-up Cancer detection rate: Low
  Population:    Single reading + CAD: 4.2/1000. Retrospective study (controlled for age and time since last screening).
  231 221 women    Double reading: 4.46/1000 (NS).  
  2001-05 n=118,808.    
   I.2: Double reading    Follow-up time unclear.
      Screening situation not applicable to European conditions (i.e. recall rate higher than accepted in Europe).
  Single reading + CAD: specialists in mammography.     
   n=112,413.   Recall rate:  
     Single reading + CAD: 10.6 %.  
  Double reading: Specialists in mammography + radiology.    Double reading:11.9%.  
     Difference statistically significant (p=0.001).  
      Invitation procedure and blinded readings unclear.
     Single reading + CAD: Se= 90.4 % Scanned analogue mammograms.
     Double reading:  
     Se=88.0 %.  
     Difference statistically significant.  
     Percent of recalled with cancer:  
     Single reading + CAD: 3.9%.  
     Double reading: 3.7%
Georgian-Smith et al., 2007 [68] Prospective I.1: Single reading + CAD Biopsy and at least 12 months´ follow-up to detect false negatives. Cancer detection rate: Low
  Study period: 2001-03    Single reading +CAD: 2.0/1000. Screening situation not applicable to European conditions. Invitation procedure not described.
   n=6381.   Double reading: 2.4/1000 (NS).  
  Population: 6381 consecutive screening examinations     
   I.2: Double reading    
     Recall rate: Population, selection criteria, withdrawals unclear.
   n=6381.   Single reading +CAD: 7.87%.  
     Double reading: 7.93% (NS).  
  Readers:     Not independent double reading but blinded to CAD
  Experienced breast radiologists    Accuracy:  
     Sensitivity and specificity not reported. Number of recalls based on all readings.
  Single reading + CAD.     Scanned analogue radiographs.
  Double reading: Not independent reading.     
Khoo et al., 2005 [70] Prospective I.1: Single reading +CAD n= 6111. Biopsy Cancer detection rate: Low
  Study period: not reported.   Not reported Total for double reading + single reading + symptomatic patients:10/1000. A so-called relative sensitivity used since 3-year follow-up not yet achieved.
    No follow-up   
  Population: 6,111 women (45-94 years), screening every 3rd year     
     Not reported individually for the groups.  
      Relatively high screening age and long screening intervals.
   I.2: Double reading n= 6111.    
     Recall rate:  
     Single reading + CAD: 6.1%. Unclear whether the readings were blinded.
     Double reading: 5.0 %. Incomplete follow-up.
  Readers:    Difference statistically significant Scanned analogue radiographs.
  Radiologists (n=7) and specially trained staff (n=5).     
     Accuracy: (relative sensitivity)*  
     Single reading + CAD: Se= 91.5%.  
     Double reading: Se= 98.4% (NS).  
  Double reading not always performed by two radiologists.     
  1. * Relative sensitivity= number of detected cancer cases per reader divided by all detected cancer cases (due to lack of follow-up).