TABLE 2.
Sensitivity, specificity, positive and negative predictor values of the blood pressure drop, slope and quadratic coefficients for ‘white-coat’ and ‘masked’ effects
| Condition | Predictor | Predictor thresholda | AUC (95% CI) | Sensitivity (95% CI) | Sensitivity rangeb | Specificity (95% CI) | Specificity (range)b | PPV (95% CI) | PPV (range)b | NPV (95% CI) | NPV (range)b |
| White-coat effectc | BP drop | More than −11 mmHg | 0.78 (0.72–0.84) | 90% (82–95%) | 90–93% | 50% (41–59%) | 42–53% | 56% (48–65%) | 22–62% | 88% (78–94%) | 86–96% |
| Slope | Below –0.60 | 0.74 (0.67–0.80) | 92% (85–97%) | 91–93% | 29% (21–38%) | 28–40% | 48% (41–56%) | 27–52% | 84% (70–93%) | 80–95% | |
| Quadratic | Above –0.27 | 0.69 (0.62–0.77) | 90% (82–95%) | 90–91% | 27% (20–36%) | 22–37% | 47% (40–55%) | 26–45% | 80% (65–90%) | 82–94% | |
| Slope + quadratic | Above –0.96 | 0.78 (0.72–0.84) | 90% (82–95%) | 90–93% | 49% (40–57%) | 39–50% | 56% (47–64%) | 21–60% | 87% (77–94%) | 86–96% | |
| Masked effectd | BP drop | Less than –19 mmHg | 0.77 (0.68–0.86) | 91% (76–98%) | 90–100% | 40% (33–47%) | 22–53% | 21% (15–29%) | 3–27% | 96% (89–99%) | 93–100% |
| Slope | Above –9.22 | 0.76 (0.67–0.85) | 94% (80–99%) | 90–100% | 42% (35–49%) | 20–42% | 22% (16–30%) | 7–25% | 98% (91–100%) | 98–100% | |
| Quadratic | Below 0.95 | 0.72 (0.62–0.82) | 91% (76–98%) | 90–100% | 36% (29–44%) | 13–39% | 20% (14–28%) | 7–23% | 96% (88–99%) | 96–99% | |
| Slope + quadratic | Above –2.31 | 0.79 (0.71–0.87) | 91% (76–98%) | 83–92% | 48% (41–56%) | 41–73% | 24% (17–32%) | 6–31% | 97% (91–99%) | 97–99% |
AUC, area under the curve; BP, blood pressure; CI, confidence interval; NPV, negative predictive value; PPV, positive predictive value.
aPredictor threshold refers to the thresholds for white-coat/masked effect on the predictor (BP drop, slope and/or quadratic) scale.
bThe range of values from sensitivity analysis (using alternative boundaries for white-coat, normal and masked effects).
cThe white-coat effect group was defined as any patient with a home–clinic difference of less than −0.2 SDs (−17.7 mmHg) below the mean.
dThe masked effect group was defined as any patient with a home–clinic difference of greater than +1.1 SDs (5.0 mmHg) above the mean.