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Categorise birthweight centiles into size-for-gestational age strata

Source: R/growth_categorise.R
categorise_sfga.Rd

Categorise birthweight centiles into size-for-gestational age strata

Usage

categorise_sfga(p, severe = FALSE)

Arguments

p

A numeric vector with birth weight centiles from the INTERGROWTH-21st Newborn Size standard. If elements of p are not between 0 and 1, gigs will warn you. You can customise this behaviour with the GIGS package-level options.

severe

A single logical value specifying whether to categorise SGA values below the third centile as "SGA(<3)". Default = FALSE.

Value

An object of class factor with the same length as p, containing size-for-GA classifications. If severe = FALSE, levels are c("SGA", "AGA", "LGA"). If severe = TRUE, levels are c("SGA(<3)", "SGA", "AGA", "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 size-for-gestational age categorisations are:

CategoryFactor levelCentile bounds
Severely small-for-GA"SGA(<3)"p < 0.03
Small-for-GA"SGA"p < 0.1
Appropriate-for-GA"AGA"0.1 =< p =< 0.9
Large-for-GA"LGA"p > 0.9

Note

Input vectors are recycled by vctrs::vec_recycle_common(), and must adhere to the vctrs recycling rules.

References

WHO. Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee. World Health Organisation Technical Report Series 1995, 854: 1–452

Royal College of Obstetricians and Gynaecologists. The Investigation and Management of the Small-for-Gestational-Age Fetus: Green-top Guideline No. 31. Technical report, Royal College of Obstetricians and Gynaecologists, London, 2013.

See also

classify_sfga(), which wraps this function for easy use in data.frame-based analytic pipelines.

Examples

p <- c(0.01, 0.07, 0.25, 0.75, 0.93, 0.99)
categorise_sfga(p = p, severe = FALSE)
#> [1] SGA SGA AGA AGA LGA LGA
#> Levels: SGA AGA LGA
categorise_sfga(p = p, severe = TRUE)
#> [1] SGA(<3) SGA     AGA     AGA     LGA     LGA    
#> Levels: SGA(<3) SGA AGA LGA