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Calculate Severe Anemia Prevalence from DHS Data (Core Function)

Source: R/indicator_anemia.R
calc_severe_anemia_dhs_core.Rd

Core function that estimates severe anemia prevalence (Hb < 8.0 g/dL) among children aged 6-59 months using standard DHS methodology. This indicator represents clinically significant anemia requiring medical attention.

Usage

calc_severe_anemia_dhs_core(
  dhs_pr,
  survey_vars = list(cluster = "hv001", weight = "hv005", stratum = "hv022", adm1 =
    "hv024", adm2 = NULL, age = "hc1", hemoglobin = "hc56", hemoglobin_adj = "hw53",
    present = "hv103", mother = "hv042"),
  hb_threshold = 8,
  altitude_adjusted = TRUE,
  gps_data = NULL,
  gps_vars = list(cluster = "DHSCLUST", lat = "LATNUM", lon = "LONGNUM")
)

Arguments

dhs_pr

DHS Person Records dataset in tidy format (data.frame or tibble).

survey_vars

Named list mapping DHS variable names. Required keys:

  • cluster: Cluster ID (default: "hv001")

  • weight: Survey weight (default: "hv005", divided by 1,000,000)

  • stratum: Explicit stratum variable if available (default: "hv022")

  • adm1: First administrative level (default: "hv024")

  • adm2: Second administrative level (default: NULL)

  • age: Child's age in months (default: "hc1")

  • hemoglobin: Raw hemoglobin in tenths of g/dL (default: "hc56")

  • hemoglobin_adj: Altitude-adjusted hemoglobin (default: "hw53")

  • present: Present in household (1=yes, default: "hv103")

  • mother: Mother listed in household (1=yes, default: "hv042")

hb_threshold

Hemoglobin threshold in g/dL for severe anemia (default: 8.0). Children with Hb < threshold are classified as severely anemic.

altitude_adjusted

Logical. If TRUE (default), uses altitude-adjusted hemoglobin variable (hw53). If FALSE, uses raw hemoglobin (hc56). WHO recommends altitude adjustment for surveys in regions above 1000m.

gps_data

Optional DHS GPS dataset. If provided, results are cluster-level.

gps_vars

Named list for GPS variables (cluster, lat, lon).

Value

A tibble with severe anemia estimates, confidence intervals, and sample sizes. Columns depend on whether GPS data is provided (cluster-level vs admin-level).

Details

Note: Most users should use calc_severe_anemia_dhs() instead, which provides additional spatial aggregation capabilities and data dictionary support.

Methodology: https://github.com/ahadi-analytics/sntmethods/blob/master/inst/methods/anemia_dhs.yml

DHS stores hemoglobin values in tenths of g/dL (e.g., 80 = 8.0 g/dL). The function handles this conversion automatically.

Severe anemia (Hb < 8.0 g/dL) is clinically significant and typically requires medical intervention. This differs from:

  • Any anemia: Hb < 11.0 g/dL

  • Moderate anemia: Hb 7.0-9.9 g/dL

  • Mild anemia: Hb 10.0-10.9 g/dL

Altitude Adjustment: The WHO recommends adjusting hemoglobin values for altitude to account for physiological adaptation to lower oxygen at higher elevations. When altitude_adjusted = TRUE, the function uses the pre-computed altitude- adjusted variable (hw53) from DHS. This is particularly important for surveys in highland areas.

Examples

# minimal example (structure only)
# anemia <- calc_severe_anemia_dhs_core(
#   dhs_pr = pr_data,
#   altitude_adjusted = TRUE  # Use altitude-adjusted Hb (default)
# )
#
# # Use raw hemoglobin (no altitude adjustment)
# anemia <- calc_severe_anemia_dhs_core(
#   dhs_pr = pr_data,
#   altitude_adjusted = FALSE
# )