Calculate target height SDS for a single child

calculate_th() calculates the target height of a child based on the height of the biological parents, using the method proposed by Hermanussen & Cole (2003) with a simplified formula for the Dutch population. The function is not vectorized, so it only works for a single child at a time. Optionally, it can calculate the target height based on the height of the mother only, although this only works for the Dutch population.

Usage

calculate_th(
  hgtf,
  hgtm,
  sex = NULL,
  etn = NULL,
  support_missing_hgtf = FALSE,
  dec = c(1L, 3L, 3L)
)

Arguments

hgtf

Length of biological father (cm)

hgtm

Length of biological mother (cm)

sex

Character, either "male" or "female". If omitted, the functions returns c(NA, NA).

etn

Ethnicity, one of "NL" (dutch), "TU" (turkish), "MA" (moroccan), "HS" (hindustani) or "DS" (Down syndrome). If omitted, the functions returns c(NA, NA).

support_missing_hgtf

Logical, if TRUE and hgtf is missing, the function will calculate the target height based on hgtm only. This will work only for the Dutch population. If hgtm is missing, the function will always return NA. The default is support_missing_hgt = FALSE.

dec

Integer vector, length 2, indicating rounding for th and th_z, respectively

Value

 Numeric, length 3: 1) target height (cm), 2) target height

prediction error and 3) target height SDS.

Details

For children with Down syndrome (etn = "DS"), the target height formula is taken from Van Gameren-Oosterom et al. (2012), fitted directly on final height of Dutch children with Down syndrome rather than derived from parent-offspring/assortative-mating correlations. That paper does not report a prediction error distinct from the final-height SD used in the SDS formula, so th_pe and the denominator of th_z both use that same SD (6.2 boys / 7.3 girls).

References

Van Gameren-Oosterom HBM, Van Dommelen P, Oudesluys-Murphy AM, Buitendijk SE, Van Buuren S, Van Wouwe JP (2012) Healthy Growth in Children with Down Syndrome. PLoS ONE 7(2): e31079.

Author

 Stef van Buuren, 2019, 2024

Examples

calculate_th(180, 170, "male", "NL")
#> [1] 182.100   5.784  -0.246
calculate_th(NA, 170, "male", "NL", support_missing_hgtf = TRUE)
#> [1] 183.500   5.784  -0.037
calculate_th(180, 170, "male", "DS")
#> [1] 161.900   6.200  -0.247