Pulmonary fibrosis (PF) is a chronic disease that progresses, or worsens, over time—though how quickly or slowly it progresses for each individual varies. While some chronic diseases have definable stages that allow you to understand how fast the disease is or will advance, PF is different. “There is no formal staging system for pulmonary fibrosis. Physicians use different factors…to describe the disease as mild, moderate, severe, or very severe,” according to the American Lung Association (ALA).

Knowing how frequently you’re coughing can help your doctor determine how severe your PF is.
(This image is from Freepik.)

The four main factors that doctors use to determine the severity of your pulmonary fibrosis are:

1. Symptoms: Common symptoms of pulmonary fibrosis include shortness of breath (dyspnea) and a dry cough. Other symptoms include achy muscles and joints, fatigue, unexplained weight loss, and clubbing (widening and rounding) of the tips of your fingers and/or toes. Your doctor can start to gauge disease severity based on how frequently you feel out of breath and are coughing.
2. Pulmonary function tests (PFTs): Also referred to as lung function tests, these types of tests focus on how much air you can hold in your lungs and how easily and quickly you can empty your lungs. A PFT allows your doctor to measure your forced vital capacity (FVC), which is the amount of air you forcibly exhale after taking a deep breath. The most common PFT is called spirometry and is used to diagnose asthma and chronic obstructive pulmonary disease (COPD); check lung function before surgery; and determine if a disease (like PF, COPD, or asthma) is worsening or improving.
3. Six-minute walk test: This simple exercise test, in which you walk at a normal pace for six minutes, measures aerobic capacity and endurance. The six-minute walk test is used to gauge heart and lung function, including monitoring your response to treatment.
4. High-resolution CT scan (HRCT): When you have pulmonary fibrosis, your lung tissue becomes damaged and scarred. In order to see how much scarring there is on your lungs, your doctor will order an HRCT.

1. Early detection: Early detection plays a large role in a patient’s prognosis. The sooner PF or IPF is diagnosed, the better one’s chance of survival. Disease severity at the time of diagnosis is directly related to one’s life expectancy.
2. Anti-scarring treatments: While there is no cure for pulmonary fibrosis, two anti-fibrotic drugs, or anti-scarring treatments, have been approved by the U.S. Food and Drug Administration (FDA) and have clinically proven to slow PF progression.
3. Individual differences: Lung function may decline faster in some patients than others. While many live past three to five years, others experience respiratory failure before the three-year mark, and some become very ill within months.

Though it’s not used by all physicians, there is a scoring system, called the GAP Model (Gender, Age, and Physiology),  that takes into account your FVC score and diffusing capacity (how well oxygen and carbon dioxide transfer between your lungs and your blood).

Much like PF, there are no set stages for idiopathic pulmonary fibrosis (IPF), either.