Demographic and Health Surveys (DHS) /Malaria Indicators Surveys (MIS) Multi-Country Malaria Analytics

Harmonization, cleaning, survey weighting, and estimation of malaria indicators (fever, testing, care-seeking) across 20+ African countries.
Author

Ousmane Diallo, MPH-PhD

Published

November 16, 2025

Overview

This project harmonizes and analyzes 20+ DHS/MIS surveys from sub-Saharan Africa to estimate malaria-related indicators among children under five. The workflow integrates:

  • API-based acquisition of indicator-level data from the DHS REST API
  • Microdata download and management using the {rdhs} R package
  • Cross-country harmonization of DHS/MIS datasets
  • Standardization of regional categories (v024) that differ by country and survey year
  • Construction of malaria indicators (fever, testing, care-seeking)
  • Survey-weighted estimation using DHS complex design
  • Generation of Power BI / Shiny-ready analytical datasets

This project supports malaria program decision-making, RWE analyses, and subnational monitoring.

Objectives

  • Use both the DHS REST API and DHS microdata to build a multi-country malaria analytics pipeline
  • Harmonize heterogeneous DHS/MIS datasets into a unified analytical structure
  • Recode region classifications to ensure comparability across countries and years
  • Compute malaria indicators among children <5:
    • Fever
    • Testing (RDT/ Microscopy)
    • Care-seeking behavior
  • Apply survey weights and complex sampling design
  • Produce cross-country analytical tables and visualizations

Methods

Data source and acquisition

  • Used DHS KR (children under 5) microdata for malaria-related surveys in multiple African countries.
  • Survey IDs were pre-selected (e.g., via DHS Download Manager) and all corresponding KR .DTA files were stored in a project directory.
  • R scripts automatically discovered and loaded all KR files using list.files() and haven::read_dta(), allowing the pipeline to scale across countries and survey years without manual file handling.
Show code: Data source and acquisition 
# Set working directory and data path
DataDir = setwd('~/Library/CloudStorage/OneDrive-Personnel/Ousmane DIALLO/Africa_care_seeking_rate/')

# Load required libraries for data manipulation and survey analysis
library(haven)        # For reading Stata/SPSS/SAS files
library(labelled)     # For handling variable labels
library(dplyr)        # For data manipulation
library(survey)       # For complex survey data analysis
library(purrr)        # For functional programming tools
library(plyr)         # For data transformation (note: conflicts with dplyr)
library(data.table)   # For fast data manipulation
library(tidyr)        # For data tidying

## Function to read multiple files matching a pattern
# Parameters:
#   filepat: regex pattern to match filenames
#   path: directory path to search in
#   fun: function to apply to each file (e.g., read_dta)
#   encoding: character encoding (default: "latin1")
# Returns: list of dataframes that have non-missing v024 values
read.files <- function(filepat, path, fun, encoding = "latin1") {
  # Get full paths of all files matching the pattern
  filenames <- list.files(path = path, pattern = filepat, 
                          recursive = TRUE, full.names = TRUE)
  
  # Apply the reading function to each file
  dflist <- sapply(filenames, fun, simplify = FALSE)
  
  # Helper function to check if v024 variable has any missing values
  isna_v024 <- function(df) any(is.na(df$v024))
  
  # Identify dataframes with missing v024 values
  cond <- sapply(dflist, isna_v024)
  
  # Return only dataframes without missing v024 values
  dflist[!cond]
}

# Get list of all DTA (Stata) files in the data directory
filenames_all <- list.files(path = DataDir, pattern = ".*.*\\.DTA", 
                            recursive = TRUE, full.names = TRUE)

# Read all DHS (Demographic and Health Surveys) files
# that are KR (Kids Recode) files
dhs = read.files(".*KR.*\\.DTA", DataDir, read_dta)

# COMMENTED OUT: Country patterns for batch processing
# This list contains regex patterns for all countries to be analyzed
# Uncomment and use in loop for multi-country processing
# cntrs <- list(".*NGKR21.*\\.DTA", ".*NGKR4B.*\\.DTA", ".*NGKR53.*\\.DTA", 
#               ".*NGKR61.*\\.DTA", ".*NGKR6A.*\\.DTA", ".*NGKR71.*\\.DTA", ...)

Data ingestion and harmonization

  • Implemented a custom read.files() helper to:
    • Recursively identify KR datasets by filename patterns (e.g., .*KR.*\\.DTA).
    • Load each file as a data frame and drop problematic files where geographic region (v024) is missing.
  • For each dataset, selected and harmonized key DHS variables:
    • Child identifiers and survey design: v000, v001, v002, v003, v005, v021, v022, v024, v025, v101, v007, v012
    • Child survival and age: b5, b19 or hw1
    • Fever and treatment variables: h22 (fever in last 2 weeks), h32a–h32x (source of care)
  • Handled differences between surveys (e.g., when b19 is unavailable) by:
    • Using hw1 as a proxy for age in months.
    • Creating a unified b19 and region variable across all datasets.
Show code: Data ingestion and harmonization 
# Initialize list to store processed datasets from each KR file
all_countries_raw <- list()

# Loop through each DHS dataset
for(i in 1:length(dhs)){
  # Extract current dataset
  dhs_hhs = dhs[i]
  
  # Select relevant variables from the Kids Recode files:
  # - caseid: unique case identifier
  # - v000: country code and phase
  # - v001: cluster number
  # - v002: household number
  # - v003: respondent's line number
  # - v007: year of interview
  # - v012: respondent's age
  # - v101: region (often used as backup for v024)
  # - v02*: household characteristics (v021, v022, v024, v025)
  # - v005: sample weight
  # - b5: child alive (Yes/No)
  # - b*: birth history variables
  # - b8: current age of child in months
  # - h*: health variables (fever, treatment, etc.)
  # - h22: fever in last 2 weeks
  # - h32*: fever treatment source variables
  dhs_kr <- dhs_hhs %>%
    map(~dplyr::select(., caseid, v000, v001, v002, v003, v007, v012, v101, 
                       contains('v02'), v005, b5, contains('b'), b8, 
                       contains('h'), contains("h32")))
  
  ## Process each dataset in the current KR file
  dhs_data = data.frame()
  
  for(j in 1:length(dhs_kr)){
    dhs_hh = dhs_kr[j]
    
    # Convert list to data frame using plyr::ldply
    all_datasets = ldply(dhs_hh, data.table)
    
    # Error handling for variable harmonization
    tryCatch({
      # Case 1: If age variable 'b19' (age in months) exists, use it directly
      if('b19' %in% colnames(all_datasets)){
        all_datasets = all_datasets %>%
          select(v000, v001, v002, v003, v007, v005, v012, v101, v021, 
                 v024 = v101,  # Rename v101 to v024 for consistency
                 v022, v025, b5, b8, h22, b19, contains("h32")) %>%
          mutate(region = ifelse(is.na(v024), v101, v024))
        
      # Case 2: If 'hw1' exists, use it as proxy for age
      } else if('hw1' %in% colnames(all_datasets)){
        all_datasets = all_datasets %>%
          select(v000, v001, v002, v003, v007, v005, v012, 
                 v024 = v101,  # Rename v101 to v024
                 v101, v021, v022, v025, b5, b8, h22, hw1, contains("h32")) %>%
          mutate(b19 = hw1,  # Create b19 from hw1
                 region = ifelse(is.na(v024), v101, v024))
      }
      
      # Append harmonized dataset to dhs_data
      {
        dhs_data = list(bind_rows(dhs_data, all_datasets))
      }
      
    }, error = function(e){
      # Print error message if harmonization fails
      cat("ERROR :", conditionMessage(e), "\n")
    })
  }
  
  # Store harmonized dataset for this KR file
  all_countries_raw[[i]] <- dhs_data
}

# Combine all KR datasets into one large harmonized data frame
all_datasets_final <- dplyr::bind_rows(all_countries_raw)

Cohort definition and derived indicators

  • Restricted the analysis to:
    • Living children (b5 == 1)
    • Age < 60 months (b19 < 60 where available)
    • Non-missing fever information (h22 != 8).
  • Created binary outcome variables at the child level:
    • prop_fievre – child had fever in the last 2 weeks (h22 == 1).
    • prop_publ – sought care in the public sector (any of h32a–h32i > 0).
    • prop_priv – sought care in the private sector (any of h32j–h32x > 0).
    • no_trea – did not seek treatment (h32y == 0).
  • Generated survey weights and strata:
    • wt = v005 / 1,000,000
    • region = ifelse(is.na(v024), v101, v024)
    • strate = as.integer(region * 10 + as.integer(v025))
    • Re-coded v022 when missing using the constructed stratum.
View code 
#| label: cohort-definition-indicators
#| eval: false
#| code-fold: true
#| code-summary: "Show code: Cohort definition and derived indicators"

# Initialize empty data frames to store final results
all_countries_fievre = data.frame()  # For fever prevalence estimates
all_countries = data.frame()         # For care-seeking estimates

# Loop through each harmonized dataset to create analysis cohorts
for(i in 1:length(dhs)){
  dhs_hhs = dhs[i]
  
  # Get the processed data from harmonization step
  dhs_data = all_countries_raw[[i]]
  
  # Create analysis cohort with derived indicators
  for(z in 1:length(dhs_data)){
    dhs_data1 = dhs_data[z]
    
    # Case 1: If age variable exists, filter for children under 5
    if('b19' %in% colnames(dhs_data1)){
      dhs_data2 = dhs_data1 %>%
        # Apply eligibility criteria:
        # - b5 == 1: child is alive
        # - b19 < 60: child is under 5 years (under 60 months)
        # - h22 != 8: exclude "don't know" responses for fever
        map(~filter(., b5 == 1 & b19 < 60 & h22 != 8)) %>%
        map(~mutate(., 
                    # Create binary fever indicator (1 = had fever in last 2 weeks)
                    prop_fievre = ifelse(h22 == 1, 1, 0),
                    # Calculate survey weight (DHS weights divided by 1,000,000)
                    wt = v005/1000000,
                    # Create sampling strata: region*10 + urban/rural
                    strate = as.integer(region*10 + as.integer(v025)),
                    # Use constructed strata if v022 (sample strata) is missing
                    v022 = ifelse(is.na(v022), strate, v022)))
      
    # Case 2: If age variable doesn't exist (no age filter possible)
    } else if(!'b19' %in% colnames(dhs_data1)){
      dhs_data2 = dhs_data1 %>%
        # Apply eligibility criteria (no age filter)
        map(~filter(., b5 == 1 & h22 != 8)) %>%
        map(~mutate(., 
                    prop_fievre = ifelse(h22 == 1, 1, 0),
                    wt = v005/1000000,
                    # Create region variable (use v101 if v024 is missing)
                    region = ifelse(is.na(v024), v101, v024),
                    strate = as.integer(region*10 + as.integer(v025)),
                    v022 = ifelse(is.na(v022), strate, v022))) 
    }
  }
  
  # Extract country and year information for metadata
  dhs_data3 = ldply(dhs_data2)
  l = data.frame(country_name = unique(dhs_data3$v000))
  countries_sel = as.factor(l$country_name)
  year = unique(dhs_data3$v007)
  year = paste(year, collapse = '-')
  
  # Process fever treatment data for children with fever
  for(z in 1:length(dhs_data2)){
    dhs_data_finale = dhs_data2[z]
    # Convert list to data frame
    dhs_data_finale = ldply(dhs_data_finale)
    
    # Filter to include only children who had fever (h22 == 1)
    dhs_data_finale1 = dhs_data_finale %>%
      filter(h22 == 1)
    
    # Create treatment source indicators:
    # h32a-h32i: public sector sources
    #   (government hospital, health center, health post, mobile clinic, 
    #    community health worker, government doctor, government nurse, etc.)
    # h32j-h32x: private sector sources
    #   (private hospital/clinic, pharmacy, drug store, private doctor,
    #    private nurse, traditional healer, shop, etc.)
    # h32y: no treatment sought
    dhs_data_finale1 = dhs_data_finale1 %>%
      mutate(
        # Sum all public sector sources
        prop_publ = rowSums(dhs_data_finale1[c("h32a", "h32b", "h32c", "h32d", 
                                               "h32e", "h32f", "h32g", "h32h", 
                                               "h32i")], na.rm = TRUE),
        # Sum all private sector sources
        prop_priv = rowSums(dhs_data_finale1[c("h32j", "h32k", "h32l", "h32m", 
                                               "h32n", "h32o", "h32p", "h32q", 
                                               "h32r", "h32s", "h32t", "h32u", 
                                               "h32v", "h32w", "h32x")], na.rm = TRUE),
        # Convert to binary indicators (1 if any source in sector used)
        prop_publ = ifelse(prop_publ > 0, 1, 0),
        prop_priv = ifelse(prop_priv > 0, 1, 0),
        # Create no treatment indicator
        no_trea = ifelse(h32y == 0, 0, 1))
    
    # Convert back to list format for estimation functions
    dhs_data_finale1 = list(dhs_data_finale1)
  }
}

Survey design and estimation

  • Defined complex survey designs with the survey package:
    • svydesign(ids = ~v021, strata = ~v022, weights = ~wt, nest = TRUE)
  • Computed region-level estimates for each country:
    • Fever prevalence: svyby(~prop_fievre, by = ~region + country_name, FUN = svymean, vartype = "se" or "ci")
    • Public-sector care-seeking: svyby(~prop_publ, ...)
    • Private-sector care-seeking: svyby(~prop_priv, ...)
    • No treatment: svyby(~no_trea, ...)
  • Exported final indicator tables to CSV (prop_fever_finale.csv, treatement_seeking.csv, etc.) to be used in mapping tools, dashboards (Shiny, Power BI), or reporting.
Show code: Survey design and estimation 
# Loop through each country/survey to calculate weighted estimates
for(i in 1:length(dhs)){
  
  # Get processed data from previous steps
  dhs_data = all_countries_raw[[i]]
  dhs_data2 = # ... (from cohort definition step)
  dhs_data_finale1 = # ... (from cohort definition step)
  
  # Extract metadata
  dhs_data3 = ldply(dhs_data2)
  l = data.frame(country_name = unique(dhs_data3$v000))
  countries_sel = as.factor(l$country_name)
  year = unique(dhs_data3$v007)
  year = paste(year, collapse = '-')
  
  # Set option for handling lonely PSUs (primary sampling units)
  # "adjust" method: centers lonely PSU data at the sample grand mean
  options(survey.lonely.psu = "adjust")
  
  # ===========================================================================
  # PART 4A: Estimate fever prevalence by region
  # ===========================================================================
  est_data <- data.frame()
  vars <- c('prop_fievre')
  
  for (y in 1:length(vars)) {
    col <- list(vars[y])
    by <- list('region')
    
    # Remove missing values for the current variable
    df <- dhs_data2 %>% 
      map(~drop_na(., vars[y]))
    
    # Apply survey-weighted estimation function (estim_prop)
    # This function should create svydesign and use svyby to calculate means
    # Format: svydesign(ids = ~v021, strata = ~v022, weights = ~wt, data = .)
    #         svyby(~prop_fievre, by = ~region, design, svymean)
    df <- pmap(list(df, col, by), estim_prop)
    df <- plyr::ldply(df)
    
    # Add metadata columns
    df$year = year
    df$country_name = countries_sel
    
    # Format and select final columns
    est_data = bind_rows(est_data, df) %>%
      select(country_name, region, year, prop_fievre) %>%
      mutate(prop_fievre = round(prop_fievre, 2))
  }
  
  # Append to master fever prevalence dataset
  all_countries_fievre = bind_rows(all_countries_fievre, est_data)
  
  # ===========================================================================
  # PART 4B: Estimate care-seeking patterns by region (public, private, none)
  # ===========================================================================
  care_data <- list()
  vars1 <- c('prop_publ', 'prop_priv', 'no_trea')
  
  for (a in 1:length(vars1)) {
    col <- list(vars1[a])
    by <- list('region')
    
    # Convert list to data frame
    df1 <- dhs_data_finale1
    df1 = ldply(df1)
    
    # Extract metadata
    l = data.frame(country_name = unique(df1$v000))
    countries_sel = as.factor(l$country_name)
    year = unique(df1$v007)
    year = paste(year, collapse = '-')
    
    # Convert back to list for estimation
    df1 = list(df1)
    
    # Apply survey-weighted estimation
    df1 <- pmap(list(df1, col, by), estim_prop)
    df1 <- plyr::ldply(df1)
    
    # Add metadata
    df1$year = year
    df1$country_name = countries_sel
    df1[, vars1[a]] = df1[, vars1[a]]
    
    # Store in list
    care_data[[a]] = df1
  }
  
  # Combine all care-seeking estimates into one dataset
  prop_estimation = bind_cols(care_data[[1]], care_data[[2]], care_data[[3]]) %>%
    rename_at(1, ~"region") %>% 
    rename_at(4, ~"year") %>% 
    rename_at(5, ~"country_name") %>%
    select(country_name, region, prop_publ, prop_priv, no_trea, year) %>%
    mutate(prop_publ = round(prop_publ, 2),
           prop_priv = round(prop_priv, 2),
           no_trea = round(no_trea, 2))
  
  # Append to master care-seeking dataset
  all_countries = bind_rows(all_countries, prop_estimation)
}

# ===========================================================================
# FINAL OUTPUT: Merge fever prevalence with care-seeking estimates
# ===========================================================================
all_countries_finale = all_countries_fievre %>% 
  left_join(all_countries, by = c('country_name', 'region', 'year'))

# Export final datasets (uncomment to save)
# write.csv(all_countries_finale, 
#           'data_care_seeking_final.csv', 
#           row.names = FALSE)

Outputs

  • Produced standardized, region-level datasets with:
    • Fever prevalence among children under 5.
    • Proportion of febrile children seeking care in public vs private facilities.
    • Proportion of febrile children not receiving any treatment.
  • Designed the pipeline to work across multiple African countries and survey years, enabling cross-country comparisons and time trends in malaria-related care-seeking behaviour.

Ousmane Diallo, MPH-PhD – Biostatistician, Data Scientist & Epidemiologist based in Chicago, Illinois, USA. Specializing in SAS programming, CDISC standards, and real-world evidence for clinical research.

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