WHO Cardiovascular Disease Risk Calculator

Implements the 2019 World Health Organization (WHO) cardiovascular disease (CVD) risk prediction models, as described in Kaptoge et al. (2019) . Provides two validated models for estimating 10-year risk of fatal and non-fatal cardiovascular events (myocardial infarction and stroke): a laboratory-based model using age, sex, systolic blood pressure, total cholesterol, smoking status, and diabetes history; and a non-laboratory-based model substituting body mass index (BMI) for cholesterol and diabetes, suitable for resource-limited settings. Risk estimates are recalibrated to 21 Global Burden of Disease regions using region-specific incidence rates and risk factor distributions derived from the Emerging Risk Factors Collaboration. Functions are fully vectorized for efficient batch calculations and support automatic country-to-region mapping via ISO 3166-1 alpha-3 country codes.

WHOrisk: WHO Cardiovascular Disease Risk Calculator

An R package implementing the 2019 WHO cardiovascular disease (CVD) risk prediction models for 21 global regions.

Overview

This package calculates 10-year risk of cardiovascular disease (fatal and non-fatal myocardial infarction and stroke) using the WHO risk charts published in The Lancet Global Health (2019).

Reference: > Kaptoge S, Pennells L, De Bacquer D, et al. World Health Organization cardiovascular disease risk charts: revised models to estimate risk in 21 global regions. Lancet Glob Health. 2019;7(10):e1332-e1345. doi:10.1016/S2214-109X(19)30318-3{.uri}

Features

• Two models available:
  • Laboratory-based model (requires cholesterol measurement)
  • Non-laboratory-based model (uses BMI instead, suitable for resource-limited settings)
• Fully vectorized for efficient batch calculations
• Zero dependencies - uses only base R
• Automatic country-to-region mapping using ISO 3166-1 alpha-3 country codes
• 21 global regions with region-specific recalibration

Installation

# Install from source
install.packages("WHOrisk", repos = NULL, type = "source")

# Or using devtools
devtools::install_local("path/to/WHOrisk")

Usage

Laboratory-Based Model

library(WHOrisk)

# Single patient calculation using region
risk <- calculate_who_risk(
  age = 55,
  sex = "male",
  sbp = 140,
  cholesterol = 5.5,  # mmol/L
  smoking = TRUE,
  diabetes = FALSE,
  region = "western_europe"
)
print(paste0("10-year CVD risk: ", round(risk * 100, 1), "%"))

# Using country code instead of region
risk <- calculate_who_risk(
  age = 60,
  sex = "female",
  sbp = 130,
  cholesterol = 6.0,
  smoking = FALSE,
  diabetes = TRUE,
  country = "ITA"  # Italy -> western_europe
)

# Vectorized calculation for multiple patients
risks <- calculate_who_risk(
  age = c(45, 55, 65, 75),
  sex = c("male", "female", "male", "female"),
  sbp = c(120, 140, 160, 150),
  cholesterol = c(5.0, 6.0, 7.0, 5.5),
  smoking = c(FALSE, TRUE, FALSE, FALSE),
  diabetes = c(FALSE, FALSE, TRUE, TRUE),
  country = c("USA", "GBR", "IND", "JPN")
)

Non-Laboratory-Based Model

For settings where cholesterol measurement is not available:

risk <- calculate_who_risk_nonlab(
  age = 55,
  sex = "male",
  sbp = 140,
  bmi = 28,
  smoking = TRUE,
  region = "south_asia"
)

Utility Functions

# Get list of valid regions
get_regions()

# Get country code mappings
get_country_codes()

# Look up specific countries
get_country_codes(c("USA", "GBR", "IND"))

# Map country to region
country_to_region(c("FRA", "DEU", "ITA"))  # All return "western_europe"

Model Details

Variables and Centering

Valid Ranges

• Age: 40-80 years (model derivation range)
• Systolic BP: Typically 70-250 mmHg
• Cholesterol: 2-12 mmol/L (divide mg/dL by 38.67)
• BMI: 12-60 kg/m²

21 Global Regions

Algorithm

The model calculates separate 10-year risks for: 1. Myocardial infarction / CHD death 2. Stroke

These are combined assuming independence:

P(CVD) = 1 - (1 - P(MI)) × (1 - P(Stroke))

Risk is calculated using Cox proportional hazards:

P(event) = 1 - S₀^exp(LP)

Where: - S₀ = region-specific baseline survival (from GBD incidence data) - LP = linear predictor including main effects and age interactions

Cholesterol Unit Conversion

The model uses mmol/L. To convert from mg/dL:

cholesterol_mmol <- cholesterol_mg_dl / 38.67

Limitations

1. Age range: Model was derived for ages 40-80. Extrapolation outside this range is less reliable.

2. Non-laboratory model: Does not include diabetes, so may underestimate risk in diabetic patients.

3. Regional calibration: Based on 2017 GBD estimates; actual risk may vary by specific country or population.

4. Risk factors not included: Family history, ethnicity, HDL cholesterol, triglycerides, etc.

License

MIT License. See LICENSE file for details.

The underlying risk models are from the WHO CVD Risk Chart Working Group.