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Table 2 Performance of the PHQ-9 and PHQ-2 to detect major depressive disorder among chronic care patients (n = 676)

From: The validity of the Patient Health Questionnaire for screening depression in chronic care patients in primary health care in South Africa

  PHQ-9 PHQ-2
Cut point Sensitivity (%) Specificity (%) Correctly classified (%) LR + a LR-b Sensitivity (%) Specificity (%) Correctly classified (%)
(≥0) 100.0 0.0 11.4 1.000   100.0 0.0 11.4
(≥1) 100.0 21.4 30.3 1.2718 0.0000 80.5 57.9 60.5
(≥2) 97.4 37.1 43.9 1.5476 0.0701 59.7 83.5 80.8
(≥3) 90.9 52.4 56.8 1.9107 0.1734 39.0 91.7 85.7
(≥4) 87.0 63.3 66.0 2.3691 0.2053 19.5 97.8 88.9
(≥5) 80.5 71.8 72.8 2.8539 0.2714 9.1 99.3 89.1
(≥6) 71.4 79.1 78.2 3.4229 0.3611 0.0 100.0 88.6
(≥7) 64.9 85.6 83.3 4.5228 0.4094    
(≥8) 53.2 90.6 86.4 5.6955 0.5157    
(≥9) 49.3 93.7 88.6 7.7792 0.5408    
(≥10) 41.6 96.5 90.2 11.8540 0.6056    
(≥11) 36.4 98.2 91.1 19.8016 0.6483    
(≥12) 32.5 98.5 91.0 21.6090 0.6856    
(≥13) 26.0 98.5 90.2 17.2872 0.7516    
(≥14) 24.7 98.8 90.4 21.1150 0.7622    
(≥15) 19.5 99.5 90.4 38.8963 0.8092    
(≥16) 14.3 99.7 89.9 42.7863 0.8600    
(≥17) 9.1 99.7 89.4 27.2276 0.9121    
(≥19) 9.1 99.4 89.5 54.4541 0.9106    
(≥20) 3.9 99.8 88.9 23.3375 0.9626    
(≥21) 2.6 99.8 88.8 15.5583 0.9757    
(≥22) 1.3 100.0 88.8   0.9870    
(≥22) 0.0 100.0 88.6   1.0000    
  1. The SCID depression module was used as the diagnostic reference standard
  2. aLikelihood Ratio Positive
  3. bLikelihood Ratio Negative