Categorise head circumference-for-age z-scores into head circumference-for-age strata

Usage

categorise_headsize(hcaz)

Arguments

hcaz: A numeric vector of length one or more containing head circumference-for-age z-scores (HCAZs).

Value

An object of class factor with the same length as hcaz, containing head circumference-for-age classifications. Its levels are c("microcephaly_severe", "microcephaly", "normal_headcirc", "macrocephaly", "macrocephaly_severe"). 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 head size categories are:

Category	Factor level	Z-score bounds
Severe microcephaly	`"microcephaly_severe"`	`hcaz` =< -3
Microcephaly	`"microcephaly"`	-3 < `hcaz` =< -2
Normal head circumference	`"normal_headcirc"`	`abs(hcaz)` < 2
Macrocephaly	`"macrocephaly"`	`hcaz` >= 2
Severe macrocephaly	`"macrocephaly_severe"`	`hcaz` >= 3

References

Victora CG, Schuler-Faccini L, Matijasevich A, Ribeiro E, Pessoa A, Barros FC. Microcephaly in Brazil: how to interpret reported numbers? The Lancet 2016, 387(10019):621-624 doi:10.1016/S0140-6736(16)00273-7

Accogli A, Geraldo AF, Piccolo G, Riva A, Scala M, Balagura G, et al. Diagnostic Approach to Macrocephaly in Children. Frontiers in Paediatrics 2022, 9:794069 doi:10.3389/fped.2021.794069

Examples

hcaz <- c(-6.5, -3.5, -2.5, 0, 2.5, 3.5)
categorise_headsize(hcaz)
#> [1] microcephaly_severe microcephaly_severe microcephaly       
#> [4] normal_headcirc     macrocephaly        macrocephaly_severe
#> 5 Levels: microcephaly_severe microcephaly normal_headcirc ... macrocephaly_severe