The GAP index for idiopathic pulmonary fibrosis mortality offers a systematic way to assess disease severity and predict mortality risk. This tool is based on four factors: gender, age, and lung function measurements expressed as predicted forced vital capacity (FVC) and predicted diffusing capacity of the lungs for carbon monoxide (DLCO). Each factor is scored, and these scores are aggregated to determine a mortality risk stage.

The scoring works as follows:

- **Gender**: 
  - Female: 0
  - Male: 1

- **Age**: 
  - 60 years or younger: 0
  - 61 to 65 years: 1
  - Older than 65 years: 2

- **Predicted FVC**:
  - Greater than 75%: 0
  - 50% to 75%: 1
  - Less than 50%: 2

- **Predicted DLCO**:
  - Greater than 55%: 0
  - 36% to 55%: 1
  - 35% or less: 2
  - Cannot perform test: 3

By summing the points across these categories, the total score is calculated, ranging from 0 to 8. This score is then used to evaluate the stage of mortality risk:

- **Stage I (Score 0-3)**: Represents the least severe level, where the mortality risk is relatively low. Statistics suggest a 5.6% probability of mortality at 1 year, increasing to 10.9% at 2 years, and reaching 16.3% by 3 years.
  
- **Stage II (Score 4-5)**: At this mid-level stage, the risk is more pronounced. There's a 16.2% chance of mortality at 1 year, which rises significantly to 29.9% after 2 years and 42.1% after 3 years.

- **Stage III (Score 6-8)**: This indicates a high severity with a marked increase in risk. Mortality is 39.2% at 1 year, escalating to 62.1% at 2 years, and peaks at 76.8% by the third year.

This structured evaluation helps in understanding the potential progression and outcomes associated with idiopathic pulmonary fibrosis, providing critical insights for both healthcare providers and patients.

The GAP index for idiopathic pulmonary fibrosis mortality is a prognostic tool designed to predict one, two, and three-year mortality rates in patients with idiopathic pulmonary fibrosis. The index incorporates four primary components: gender, age, and two pulmonary function tests - forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO). Each component is assigned a score based on the patient's characteristics. For gender, males are assigned a higher score. Age is divided into three categories, with older patients receiving higher scores. Predicted FVC and DLCO are also divided into categories, with lower percentages of predicted values receiving higher scores. Patients unable to perform the DLCO test are assigned the highest score for that component. The total score is then used to estimate the patient's mortality risk.