Categorise birthweight centiles and gestational ages into small vulnerable newborn strata
Source:R/growth_categorise.R
categorise_svn.RdCategorise birthweight centiles and gestational ages into small vulnerable newborn strata
Arguments
- p
A numeric vector with birth weight centiles from the INTERGROWTH-21st Newborn Size standard. If elements of
pare not between0and1, gigs will warn you. You can customise this behaviour with the GIGS package-level options.- gest_days
A numeric vector of length one or more with gestational age(s) in days. Used to determine whether infants are term or preterm (a gestational age > 259 days means an infant is term).
Value
An object of class factor with the same length as the longest input
vector, containing small vulnerable newborn classifications. Its levels
are c("Preterm SGA", "Preterm AGA", "Preterm LGA", "Term SGA", "Term AGA", "Term LGA"). By default, gigs will inform you this object contains unused
factor levels. You can change this behaviour using the
GIGS package-level option
.gigs_options$handle_unused_levels.
Details
Cut-offs for small, vulnerable newborn categorisations are:
| SVN category | Factor level | Centile bounds | Gestational age range |
| Preterm-SGA | "Preterm SGA" | p < 0.1 | gest_days < 259 |
| Preterm-AGA | "Preterm AGA" | 0.1 =< p =< 0.9 | gest_days < 259 |
| Preterm-LGA | "Preterm LGA" | p > 0.9 | gest_days < 259 |
| Term-SGA | "Term SGA" | p < 0.1 | gest_days >= 259 |
| Term-AGA | "Term AGA" | 0.1 =< p =< 0.9 | gest_days >= 259 |
| Term-LGA | "Term LGA" | p > 0.9 | gest_days >= 259 |
Abbreviations: SGA, small-for-gestational age; AGA, appropriate-for-gestational age; LGA, large-for-gestational age.
Note
Input vectors are recycled by vctrs::vec_recycle_common(), and must
adhere to the vctrs recycling rules.
References
Lawn JE, Ohuma EO, Bradley E, Idueta LS, Hazel E, Okwaraji YB et al. Small babies, big risks: global estimates of prevalence and mortality for vulnerable newborns to accelerate change and improve counting. The Lancet 2023, 401(10389):1707-1719. doi:10.1016/S0140-6736(23)00522-6
See also
classify_svn(), which wraps this function for easy use in
analytic pipelines. Also check out categorise_sfga(), which this function
uses to stratify p into size-for-gestational age categories.
Examples
p <- c(0.01, 0.07, 0.25, 0.75, 0.93, 0.99)
gest_days <- c(250, 250, 250, 280, 280, 280) # 3 preterm, 3 term
categorise_svn(p = p, gest_days = gest_days)
#> ! Unused factor levels kept after small vulnerable newborn categorisation:
#> "Preterm LGA" and "Term SGA".
#> [1] Preterm SGA Preterm SGA Preterm AGA Term AGA Term LGA Term LGA
#> Levels: Preterm SGA Preterm AGA Preterm LGA Term SGA Term AGA Term LGA