Table 4.
NRI and Integrated Discriminative Improvement Using Predictive Equations From the Current Analysis Versus Screening Methods Based on Clinic Blood Pressure and Antihypertensive Medication Use
| Methods of Identifying Who Should Undergo 24‐h Ambulatory Blood Pressure Monitoring | Net Reclassification Index (95% CI) | |
|---|---|---|
| Nocturnal Hypertension | Nondipping Systolic Blood Pressure | |
| Overall categorical net reclassification index | ||
| Clinic SBP/DBP ≥120/70 mm Hg | 0.29 (0.20 to 0.40) | 0.26 (0.18 to 0.34) |
| Clinic SBP/DBP ≥130/80 mm Hg | 0.23 (0.12 to 0.34) | 0.12 (0.03 to 0.21) |
| Clinic SBP/DBP ≥140/90 mm Hg | 0.24 (0.14 to 0.34) | 0.24 (0.15 to 0.33) |
| Antihypertensive medication use | 0.11 (0.02 to 0.19) | 0.25 (0.16 to 0.34) |
| Negative categorical net reclassification index | ||
| Clinic SBP/DBP ≥120/70 mm Hg | 0.41 (0.34 to 0.48) | 0.38 (0.32 to 0.44) |
| Clinic SBP/DBP ≥130/80 mm Hg | 0.02 (−0.06 to 0.09) | −0.03 (−0.09 to 0.02) |
| Clinic SBP/DBP ≥140/90 mm Hg | −0.25 (−0.31 to −0.19) | −0.26 (−0.32 to −0.22) |
| Antihypertensive medication use | −0.14 (−0.20 to −0.10) | −0.09 (−0.15 to −0.05) |
| Positive categorical net reclassification index | ||
| Clinic SBP/DBP ≥120/70 mm Hg | −0.12 (−0.19 to −0.04) | −0.12 (−0.17 to −0.06) |
| Clinic SBP/DBP ≥130/80 mm Hg | 0.21 (0.12 to 0.30) | 0.16 (0.08 to 0.24) |
| Clinic SBP/DBP ≥140/90 mm Hg | 0.49 (0.42 to 0.57) | 0.51 (0.43 to 0.58) |
| Antihypertensive medication use | 0.25 (0.19 to 0.32) | 0.34 (0.27 to 0.42) |
| Continuous net reclassification index | ||
| Models using SBP, DBP, and antihypertensive medication usea | 0.52 (0.35 to 0.69) | 0.51 (0.34 to 0.69) |
| Integrated discriminative improvement index | ||
| Models using SBP, DBP, and antihypertensive medication use | 0.10 (0.07 to 0.12) | 0.07 (0.04 to 0.09) |
Table values were computed using the validation data. For categorical net reclassification indexes, the probability cut points maximizing the Youden index for the predictive equations (0.34 and 0.43 for nocturnal hypertension and nondipping systolic blood pressure, respectively) were used. These cut points were chosen assuming that they provide better overall classification characteristics than the other 3 cut points. DBP indicates diastolic blood pressure; NRI, net reclassification improvement; SBP, systolic blood pressure.
Predicted probabilities were obtained from equations formed for nocturnal hypertension and nondipping systolic blood pressure, separately, using logistic regression in the derivation data set with clinic SBP and DBP and antihypertensive medication use as independent variables.