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Classify small vulnerable newborns in data.frame-like objects with the INTERGROWTH-21st weight-for-gestational age standard

Source: R/growth_classify.R
classify_svn.Rd

Classify small vulnerable newborns in data.frame-like objects with the INTERGROWTH-21st weight-for-gestational age standard

Usage

classify_svn(
  .data,
  weight_kg,
  gest_days,
  sex,
  .new = c("birthweight_centile", "svn")
)

Arguments

.data

A data.frame-like tabular object with one or more rows. Must be permissible by checkmate::assert_data_frame(), so you can also supply a tibble, data.table, or similar.

weight_kg

<data-masking> The name of a column in .data which is a numeric vector of birth weight values in kg. It is assumed that weight measurements provided to this function are birth weights recorded <12 hours after an infant's birth.

gest_days

<data-masking> The name of a column in .data which is a numeric vector of gestational age(s) at birth in days between 168 and 300. By default, gigs will warn you about elements of this vector which are outside these bounds, are NA, or Inf. You can customise this behaviour using the GIGS package-level options.

sex

<data-masking> The name of a column in .data which is a case-sensitive character vector of sexes, either "M" (male) or "F" (female). By default, gigs will warn you if any elements of sex are not "M" or "F", or are missing (NA). You can customise this behaviour using the GIGS package-level options.

.new

A two-length character vector with names for the output columns. These inputs will be repaired if necessary using vctrs::vec_as_names(), which will print any changes to the console. If any elements in .new are the same as elements in colnames(.data), the function will throw an error. Default = c("birthweight_centile", "svn").

Value

A tabular object of the same class that was provided as .data, with two new columns named according to .new. These columns will be (from left to right):

  • birthweight_centile - Numeric vector of birthweight centiles from the INTERGROWTH-21st Newborn Size standard for weight-for-GA

  • svn - Factor of small vulnerable newborn (SVN) categories

Details

Cut-offs for small, vulnerable newborn categorisations are:

SVN categoryFactor levelCentile boundsGestational age range
Preterm-SGA"Preterm SGA"p < 0.1gest_days < 259
Preterm-AGA"Preterm AGA"0.1 =< p =< 0.9gest_days < 259
Preterm-LGA"Preterm LGA"p > 0.9gest_days < 259
Term-SGA"Term SGA"p < 0.1gest_days >= 259
Term-AGA"Term AGA"0.1 =< p =< 0.9gest_days >= 259
Term-LGA"Term LGA"p > 0.9gest_days >= 259

Abbreviations: SGA, small-for-gestational age; AGA, appropriate-for-gestational age; LGA, large-for-gestational age.

Note

Categorical (factor) columns produced here may contain unused factor levels. By default, gigs will inform you if these columns have unused factor levels. You can change this behaviour using the GIGS package-level option .gigs_options$handle_unused_levels.

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

See classify_sfga() for size-for-GA classifications which are not stratified by whether a newborn is term. See classify_growth() to run this analysis and others at the same time.

Examples

data <- data.frame(
  wt_kg = c(1.5, 2.6, 2.6, 3.5),
  gestage = c(235, 257, 275, 295),
  sex = c("F", "M", "F", "M")
)

data |>
  classify_svn(weight_kg = wt_kg,
               gest_days = gestage,
               sex = sex)
#> ! Unused factor levels kept after small vulnerable newborn categorisation:
#> "Preterm LGA" and "Term LGA".
#>   wt_kg gestage sex birthweight_centile         svn
#> 1   1.5     235   F          0.07039106 Preterm SGA
#> 2   2.6     257   M          0.27470460 Preterm AGA
#> 3   2.6     275   F          0.06389942    Term SGA
#> 4   3.5     295   M          0.36209260    Term AGA