To the Editor
High blood pressure (BP) is frequently underdiagnosed in the pediatric population mainly due to the complex diagnosis process,1 which involves the analysis of multiple tables and charts. The BP‐to‐height ratio (BPHT) is a simple screening tool that has shown good ability to identify high BP in children.2 Conversely, variations in this formula, including the modified BP‐to‐height ratio (MBPHT)3 and the new modified BP‐to‐height ratio (NMBPHT),4, 5 have been reported to provide better screening performance than the original BP‐to‐height ratio. However, a recent guideline changed the BP percentiles values in children and adolescents,6 virtually nullifying these findings. Therefore, we calculated new cut‐off points for BPHT, MBPHT, and NMBPHT using data from the new guideline and compared the performance of these methods to diagnose high BP in large Brazilian and American populations.
This study included subjects that ranged in age from 8 to 13 years and with complete information on height, weight, sex, systolic BP (SBP), and diastolic BP (DBP) from 2 distinct populations. The first population (n = 2936; 1241 girls) was obtained from a database built from medical charts in a pediatric cardiology center in Brazil.3 The second population (n = 6541; 3298 girls) was obtained from data derived from the National Health and Nutrition Examination Survey (NHANES) 1999‐2014.7, 8, 9 Only the first BP measurement was used in the analyses and details regarding the acquisition of data are reported elsewhere.3, 7, 8, 9 BP disorders were defined as SBP or DBP ≥90th percentile and hypertension was defined as SBP or DBP ≥95th percentile according to the most recent guideline.6 The BPHT formulas were: SBP or DBP (mm Hg)/Height (cm). The MBPHT formulas were: SBP or DBP (mm Hg)/7 × (13 − age [in years]). The NMBPHT were: SBP or DBP (mm Hg)/3 × (13 − age [in years]). Receiver Operator Characteristics (ROC) curves were plotted to identify optimal SBP and DBP cut‐off points to identify BP disorders or hypertension. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated with their respective 95% confidence intervals for each method. The classification of BP disorders and hypertension according to the most recent guideline6 was considered the gold standard.
Brazilian boys and girls with mean ± SD age = 10.0 ± 1.4 and 9.9 ± 1.4 years, SBP = 102.6 ± 10.0 and 102.1 ± 9.7 mm Hg, DBP = 63.1 ± 8.3 and 62.9 ± 7.9 mm Hg, height = 139.6 ± 10.3 and 139.2 ± 11.9 cm, weight = 35.5 ± 11.8 and 36.8 ± 11.5 kg, respectively, and American boys and girls with age = 10.1 ± 1.4 and 10.1 ± 1.4 years, SBP = 103.5 ± 9.7 and 102.7 ± 10.0 mm Hg, DBP = 54.5 ± 12.0 and 55.6 ± 11.1 mm Hg, height = 144.2 ± 11.3 and 145.1 ± 11.5 cm, weight = 42.3 ± 14.5 and 43.9 ± 15.2 kg, respectively, were included in the analyses. BP disorders were present in 14.8% and 15.2%, while hypertension was found in 10.2% and 7.5% of Brazilian and American children, respectively.
The cut‐off points and performance of BPHT, MBPHT, and NMBPHT in Brazilian and American children are presented in Tables 1 and 2, respectively. All methods had high sensitivity and NPV in all studied scenarios. However, NMBPHT showed superior specificity and PPV for the diagnosis of BP disorders in American and Brazilian children. Regarding the identification of hypertension, BPHT, MBPHT, and NMBPHT tended to show similar specificity and PPV in American children, while MBPHT appeared to show better performance in Brazilian children.
Table 1.
Performance of BPHT, MBPHT, and NMBPHT to detect BP disorders (BP ≥ 90th percentile) and hypertension (BP ≥ 95th percentile) in Brazilian children
| Cut‐off points (SBP/DBP) | Sensitivity, % (95% CI) | Specificity, % (95% CI) | PPV, % (95% CI) | NPV, % (95% CI) | |
|---|---|---|---|---|---|
| BPHT‐BP ≥ 90th percentile | |||||
| Male | 0.77/0.49 | 96.3 (93.3‐98.2) | 77.6 (75.4‐79.8) | 44.9 (42.5‐47.4) | 99.1 (98.4‐99.5) |
| Female | 0.76/0.49 | 98.3 (95.1‐99.7) | 74.3 (71.5‐76.9) | 38.8 (36.4‐41.3) | 99.6 (98.9‐99.9) |
| MBPHT‐BP ≥ 90th percentile | |||||
| Male | 0.67/0.42 | 100 (98.6‐100) | 77.5 (75.3‐79.7) | 45.8 (43.4‐48.2) | 100 |
| Female | 0.66/0.43 | 100 (97.9‐100) | 78.5 (75.9‐80.9) | 43.6 (40.8‐46.4) | 100 |
| NMBPHT‐BP ≥ 90th percentile | |||||
| Male | 0.73/0.48 | 98.9 (96.8‐99.8) | 88.1 (86.3‐89.8) | 61.2 (57.8‐64.6) | 99.8 (99.3‐99.9) |
| Female | 0.74/0.47 | 98.9 (96.0‐99.9) | 89.7 (87.7‐91.4) | 61.4 (57.1‐65.5) | 99.8 (99.2‐99.9) |
| BPHT‐BP ≥ 95th percentile | |||||
| Male | 0.79/0.49 | 98.9 (95.9‐99.9) | 78.0 (75.9‐80.1) | 34.1 (32.0‐36.3) | 99.8 (99.3‐100) |
| Female | 0.79/0.49 | 97.6 (93.1‐99.5) | 80.9 (78.5‐83.2) | 36.4 (33.6‐39.3) | 99. 7 (99.0‐99.9) |
| MBPHT‐BP ≥ 95th percentile | |||||
| Male | 0.69/0.45 | 98.3 (95.1‐99.6) | 89.0 (87.3‐90.5) | 50.7 (47.1‐54.3) | 99.8 (99.3‐99.9) |
| Female | 0.69/0.44 | 98.4 (94.3‐99.8) | 88.4 (86.3‐90.2) | 48.6 (44.6‐52.7) | 99.8 (99.2‐100) |
| NMBPHT‐BP ≥ 95th percentile | |||||
| Male | 0.75/0.48 | 98.3 (95.1‐99.6) | 88.4 (86.6‐89.9) | 49.3 (45.8‐52.8) | 99.8 (99.3‐99.9) |
| Female | 0.75/0.47 | 99.2 (95.6‐100) | 84.0 (81.7‐86.1) | 40.2 (37.7‐44.2) | 99.9 (99.3‐100) |
BP, blood pressure; BPHT, BP‐to‐height ratio; CI, confidence interval; DBP, diastolic BP; MBPHT, modified BP‐to‐height ratio; NMBPHT, new modified BP‐to‐height ratio; NPV, negative predictive value; PPV, positive predictive value; SBP, systolic BP.
Table 2.
Performance of BPHT, MBPHT, and NMBPHT to detect BP disorders (BP ≥ 90th percentile) and hypertension (BP ≥ 95th percentile) in American children
| Cut‐off points (SBP/DBP) | Sensitivity, % (95% CI) | Specificity, % (95% CI) | PPV, % (95% CI) | NPV, % (95% CI) | |
|---|---|---|---|---|---|
| BPHT‐BP ≥ 90th percentile | |||||
| Male | 0.77/0.48 | 93.3 (90.7‐95.4) | 81.9 (80.4‐83.3) | 48.0 (45.9‐50.0) | 98.6 (98.0‐99.0) |
| Female | 0.76/0.47 | 95.8 (93.6‐97.4) | 80.7 (79.2‐82.2) | 45.8 (43.8‐47.7) | 99.1 (98.7‐99.4) |
| MBPHT‐BP ≥ 90th percentile | |||||
| Male | 0.66/0.42 | 98.0 (96.3‐99.0) | 75.7 (74.1‐77.3) | 42.0 (40.3‐43.6) | 99.5 (99.1‐99.7) |
| Female | 0.66/0.43 | 95.0 (92.6‐96.8) | 81.5 (80.0‐82.9) | 46.5 (44.5‐48.5) | 99.0 (98.5‐99.3) |
| NMBPHT‐BP ≥ 90th percentile | |||||
| Male | 0.73/0.45 | 97.6 (95.8‐98.7) | 86.0 (84.6‐87.3) | 55.5 (53.2‐57.8) | 99.5 (99.1‐99.7) |
| Female | 0.72/0.44 | 99.2 (97.9‐99.8) | 82.0 (80.5‐83.4) | 48.2 (46.3‐50.2) | 99.8 (99.5‐99.9) |
| BPHT‐BP ≥ 95th percentile | |||||
| Male | 0.79/0.49 | 97.6 (94.9‐99.1) | 84.4 (83.1‐85.7) | 34.4 (32.5‐36.3) | 99.8 (99.5‐99.9) |
| Female | 0.78/0.49 | 97.5 (94.6‐99.1) | 84.2 (82.9‐85.5) | 32.6 (30.8‐34.5) | 99.76 (99.5‐99.9) |
| MBPHT‐BP ≥ 95th percentile | |||||
| Male | 0.68/0.44 | 95.6 (92.3‐97.8) | 83.4 (82.0‐84.7) | 32.5 (30.7‐34.4) | 99.6 (99.2‐99.8) |
| Female | 0.68/0.43 | 97.5 (94.1‐99.1) | 84.3 (83.0‐85.6) | 32.7 (30.9‐34.6) | 99.8 (99.5‐99.9) |
| NMBPHT‐BP ≥ 95th percentile | |||||
| Male | 0.75/0.46 | 100 (98.5‐100) | 79.4 (77.9‐80.9) | 28.9 (27.4‐30.3) | 100 |
| Female | 0.74/0.46 | 99.2 (97.0‐99.9) | 87.6 (86.4‐88.8) | 38.5 (36.3‐40.7) | 99.9 (99.7‐100) |
BP, blood pressure; BPHT, BP‐to‐height ratio; CI, confidence interval; DBP, diastolic BP; MBPHT, modified BP‐to‐height ratio; NMBPHT, new modified BP‐to‐height ratio; NPV, negative predictive value; PPV, positive predictive value; SBP, systolic BP.
The present study described novel cut‐off points for BPHT, MBPHT, and NMBPHT, which were built using new guideline data.6 Consistent with studies based on the former guideline10 for BP management in children,4, 5 we also showed that NMBPHT had greater performance to detect BP disorders. This superiority can be explained by the better ability of this formula to capture trunk's growth,5 which is more correlated with BP than whole body's growth.11 These findings suggest that NMBPHT is a useful tool for the screening of BP disorders in children.
FUNDING INFORMATION
Supported by a grant from the Brazilian National Council for Scientific and Technological Development, grant number: 304245/2013‐5 (to Dr. Nadruz).
CONFLICT OF INTEREST
None.
Mourato and Mourato contributed equally to this study.
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