gap_index_ipf: GAP Index for Idiopathic Pulmonary Fibrosis (IPF) Mortality

In cliot: Clinical Indices and Outcomes Tools

GAP Index for Idiopathic Pulmonary Fibrosis (IPF) Mortality

Description

Calculates the GAP (Gender, Age, Physiology) Index to predict 1-, 2-, and 3-year mortality in patients with Idiopathic Pulmonary Fibrosis. The score stratifies patients into three stages based on four predictors: sex, age, forced vital capacity (FVC), and diffusing capacity of the lung for carbon monoxide (DLCO).

Usage

gap_index_ipf(sex, age, fvc_percent, dlco_percent, dlco_unable_to_perform = 0)

Arguments

sex	String. Patient sex ("Male" or "Female"). (Male adds 1 point).
age	Numeric. Patient age in years. <= 60: 0 pts. 61-65: 1 pt. > 65: 2 pts.
fvc_percent	Numeric. Predicted Forced Vital Capacity (FVC) percentage. > 75%: 0 pts. 50-75%: 1 pt. < 50%: 2 pts.
dlco_percent	Numeric. Predicted Diffusing Capacity of the Lung for Carbon Monoxide (DLCO) percentage. Required if 'dlco_unable_to_perform' is 0. > 55%: 0 pts. 36-55%: 1 pt. <= 35%: 2 pts.
dlco_unable_to_perform	Numeric (0 or 1). Is the patient unable to perform the DLCO maneuver? (1 = Yes). If Yes, score is 3 points for this category.

Value

A list containing:

GAP_Score	The calculated total score (Range 0-8).
GAP_Stage	The disease stage (I, II, or III).
Mortality_Risk	Estimated mortality rates at 1, 2, and 3 years.

References

Ley B, Ryerson CJ, Vittinghoff E, et al. A multidimensional index and staging system for idiopathic pulmonary fibrosis. Ann Intern Med. 2012;156(10):684-691. doi:10.7326/0003-4819-156-10-201205150-00004

Examples

# Example 1: Stage I (Low Risk)
# Female (0), 55yo (0), FVC 80% (0), DLCO 60% (0)
# Score = 0
gap_index_ipf("female", 55, 80, 60)

# Example 2: Stage III (High Risk)
# Male (1), 70yo (2), FVC 45% (2), DLCO Unable (3)
# Score = 1 + 2 + 2 + 3 = 8
gap_index_ipf("male", 70, 45, 0, 1)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.