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Table 2 Rate of response and association of responses to individual questions about knee OA with symptomatic knee osteoarthritis (n = 1464)

From: Validation of a screening questionnaire for hip and knee osteoarthritis in old people

Question n Frequency of positive findings, % Sensitivity,% (95% CI) Specificity,% (95% CI) Positive Predictive Value,% (95% CI) Negative Predictive Value,% (95% CI) Odds ratio (95% CI) C statistics
1. – During the last 12 months, have you often had pain in one or both your knees for one month or more? 1413 80.96 94.77 (93.17, 96.37) 34.48 (30.87, 38.09) 61.80 (58.98, 64.62) 85.50 (81.29, 89.71) 9.54 (9.66, 13.67) 0.646
2. – Has a doctor ever told you that you have osteoarthritis in one or both of your knees? 1419 62.86 80.70 (77.87,83.53) 56.91 (53.17, 60.65) 67.49 (64.42, 70.56) 72.68 (68.88, 76.48) 5.52 (4.35, 7.00) 0.688
3. – Do you have a prosthesis in one or both of your knees? 1414 3.75 6.76 (4.95, 8.57) 99.55 (99.04,100.1) 94.34 (88.12, 100.6) 49.30 (46.64, 51.96) 16.21 (5.03, 52.21) 0.532
4. – Have you had any surgical intervention in one or both of your knees? 1415 11.38 16.40 (13.73, 19.07) 94.09 (92.31, 95.87) 75.16 (68.49, 81.83) 50.80 (48.03, 53.57) 3.12 (2.15, 4.54) 0.552
5. – During the last 12 months, have you had stiffness in one or both your knees for one month or more? 1417 48.98 64.37 (60.92, 67.82) 67.90 (64.38, 71.42) 68.73 (65.28, 72.18) 63.49 (59.98, 67.00) 3.82 (3.07, 4.77) 0.661
6. – During the last 12 months, have you had any of the following limitations because of pain or stiffness in one or both of your knees?         
   6 a. – Rising from a chair or toilet 1360 61.91 78.58 (75.58, 81.58) 56.79 (52.96, 60.62) 67.10 (63.93, 70.27) 70.27 (66.33, 74.21) 4.82 (30.80 6.11) 0.677
   6 b. – Going up steps 1380 69.71 85.44 (82.88, 88.00) 47.85 (44.02, 51.68) 64.66 (61.64, 67.68) 74.64 (70.47, 78.81) 5.38 (4.16, 6.96) 0.666
   6 c. – Going down steps 1374 70.74 88.05 (85.69, 90.41) 48.76 (44.91, 52.61) 65.95 (62.97, 68.93) 78.36 (74.33, 82.39) 7.01 (5.34, 9.20) 0.684
   6d. – Walking 4 blocks (or 500 m) 1348 55.34 70.72 (67.37, 74.07) 61.62 (57.86, 65.38) 67.02 (63.65, 70.39) 65.61 (61.82, 69.40) 3.88 (3.09, 4.87) 0.662
7. – During the last 12 months, have you often experienced any sensation of insecurity or that one or both of your knees failed? 1394 62.55 77.05 (74.00, 80.10) 53.47 (49.67, 57.27) 64.68 (61.51, 67.85) 67.82 (63.81, 71.83) 3.86 (3.07, 4.86) 0.653
  1. 95% CI = 95% confidence interval
  2. c statistics: estimated by logistic regression model