Categorise Blood Pressure (Children/Adolescents and Young Adults)

Categorises observed BP values into guideline-based categories. For ages 0-17, currently NHBPEP Fourth Report thresholds are applied (with newborn and adolescent rules). For >17, NICE/BHF adult thresholds are applied.

Unless bp_limit is explicitly provided, implausible values are excluded using:

• NPDA limit (children/adolescents): SBP [50-200] mmHg, DBP [15-150] mmHg

• NDA limit (young adults): SBP [70-300] mmHg, DBP [20-150] mmHg

Usage

bp_category(bp_value, bp_limit = c(-Inf, Inf), ..., .quiet = FALSE)

Arguments

bp_value

Numeric vector of observed BP values (mmHg).

bp_limit

Length-2 numeric vector c(min, max) giving acceptable range. Defaults to c(-Inf, Inf); if left as-is, NPDA/NDA defaults are applied based on ref.

...

Arguments passed on to .bp_validate_demo_input, bp_expected

bp_type

Character; "systolic" or "diastolic".

sex

Vector of sex codes in your data. Will be mapped to "male" or "female" using male_code and female_code. Values not matching these codes become NA.

male_code,female_code

Scalar values that identify the male and female codes in sex (e.g., 1 and 2, or "M" and "F").

height_z

Numeric vector of height z-scores. Must already be z-transformed (e.g., US CDC, UK-WHO).

height_limit

Positive numeric; z-scores with |z| > height_limit are treated as invalid and set to NA. Default 5.

age_years

Numeric vector of ages in years.

ref

Reference: "Fourth Report" (children/adolescents, 0-17) or "NICE/BHF" (adults, >17).

.quiet

Logical; suppress messages (default FALSE).

Value

Character vector of BP categories: "Normotension", "Prehypertension", "Stage 1 hypertension", "Stage 2 hypertension", or "Stage 3 hypertension" (adults only). NA where inputs are invalid or beyond specified bp_limit.

BP Categories by Age Group

Category	Age (years)	Reference	Criteria
Normotension	[0-12] (children)	NHBPEP Fourth Report (NPDA min)	(50/15mmHg \(\leq\)) SBP/DBP < 90th percentile
Normotension	(12-17] (adolescents)	NHBPEP Fourth Report (NPDA min)	(50/15mmHg \(\leq\)) SBP/DBP < 120/80 mmHg
Normotension	>17	NICE/BHF (NDA min)	(70/20mmHg \(\leq\)) SBP/DBP < 120/80 mmHg
Prehypertension	[0-12] (children)	NHBPEP Fourth Report	90th \(\leq\) SBP/DBP < 95th
Prehypertension	(12-17] (adolescents)	NHBPEP Fourth Report	120/80mmHg \(\leq\) SBP/DBP < 95th
Prehypertension	>17	NICE/BHF	120/80mmHg \(\leq\) SBP/DBP < 140/90mmHg
Stage 1 hypertension	[0-1) (newborns)	NHBPEP Fourth Report	95th \(\leq\) SBP < 5mmg above 99th
Stage 1 hypertension	[1-17]	NHBPEP Fourth Report	95th \(\leq\) SBP/DBP < 5mmg above 99th
Stage 1 hypertension	>17	NICE/BHF	140/90mmHg \(\leq\) SBP/DBP < 160/100mmHg
Stage 2 hypertension	[0-1) (newborns)	NHBPEP Fourth Report (NPDA max)	5mmg above 99th \(\leq\) SBP (\(\leq\) 200/150mmHg)
Stage 2 hypertension	[1-17]	NHBPEP Fourth Report (NPDA max)	5mmg above 99th \(\leq\) SBP/DBP (\(\leq\) 200/150mmHg)
Stage 2 hypertension	>17	NICE/BHF	160/100mmHg \(\leq\) SBP/DBP < 180/120mmHg
Stage 3 hypertension	>17	NICE/BHF (NDA max)	180/120mmHg \(\leq\) SBP/DBP (\(\leq\) 300/150mmHg)

References

• NHBPEP Fourth Report: Paediatric BP categories

• NICE Guidelines: Adult BP categories

• British Heart Foundation: Adult BP categories

• NDA Methodology: Adult BP Range

• NPDA Methodology: Paediatric BP Range

• RCPCH Growth API: Python library for Paediatric SDS calculation

• childsds package: R package for Paediatric SDS calculation

See also

Other BP functions: .bp_message(), .bp_resolve_limit(), .bp_validate_demo_input(), bp_assess(), bp_expected(), bp_family, bp_relative()

Examples

# Child/adolescent categorisation (Fourth Report):
bp_category(
  bp_value = c(95, 118, 130, 150),
  bp_type = "systolic",
  sex = c(1, 2, 1, 2),
  male_code = 1, female_code = 2,
  height_z = c(0, 0, 0, 0),
  age_years = c(8, 14, 16, 6),
  ref = "Fourth Report"
)
#> NHBPEP Fourth Report categorise 'Normotension' to 'Stage 2 hypertension'; Special rules for newborns (<1), children (0-12), adolescents (12-17).
#> BP outside National Paediatric Diabetes Audit (NPDA) limit removed unless acceptable range is explicitly specified by 'bp_limit'.
#> [1] "Normotension"         "Normotension"         "Prehypertension"     
#> [4] "Stage 2 hypertension"

# Adult categorisation (NICE/BHF; uses NDA limits if bp_limit not provided):
bp_category(
  bp_value = c(118, 135, 162, 185),
  bp_type = "diastolic",
  sex = rep("M", 4), male_code = "M", female_code = "F",
  height_z = rep(0, 4),
  age_years = c(22, 30, 45, 67),
  ref = "NICE/BHF"
)
#> NICE/BHF categorise 'Normotension' to 'Stage 3 hypertension'.
#> BP outside National Diabetes Audit (NDA) limit removed unless acceptable range is explicitly specified by 'bp_limit'.
#> [1] "Stage 2 hypertension" "Stage 3 hypertension" NA                    
#> [4] NA