Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory disorder characterized by persistent airflow limitation. The recognition of distinct clinical patterns, or phenotypes, has become a focus for improving diagnosis and treatment. One such pattern is known as PRISm, which identifies a large group of individuals with impaired lung function who do not meet the full spirometric criteria for COPD. Understanding the PRISm phenotype is changing how medical professionals view the disease spectrum, offering new insights into risk stratification and personalized care.
Defining the PRISM Phenotype
The acronym PRISm stands for Preserved Ratio Impaired Spirometry, a term that precisely describes the pattern observed in pulmonary function testing. The diagnosis hinges on specific results from spirometry, the test that measures how much air a person can inhale and exhale and how quickly they can exhale it. For a typical COPD diagnosis, the ratio of the forced expiratory volume in one second (FEV1) to the forced vital capacity (FVC)—the FEV1/FVC ratio—is abnormally low, indicating obstructive airflow limitation.
In PRISm patients, however, this FEV1/FVC ratio is preserved, meaning it is typically 0.7 or higher after the use of a bronchodilator. Despite this normal ratio, the overall lung function is impaired because the FEV1 itself is less than 80% of the value predicted for a person of the same age, sex, and height. This indicates a reduction in the total amount of air the person can forcefully exhale in the first second. PRISm is sometimes referred to as “GOLD unclassified” because it falls outside the Global Initiative for Chronic Obstructive Lung Disease (GOLD) definition of COPD, yet it represents a state of compromised respiratory health. This specific functional state is now considered a precursor or transitional state for some patients who may eventually develop full airflow obstruction.
Clinical Implications and Long-Term Risk
Identifying the PRISm phenotype carries significant prognostic implications, suggesting a risk profile far greater than that of a healthy individual with normal spirometry. Patients with PRISm frequently report increased respiratory symptoms, including chronic cough and dyspnea (shortness of breath), which negatively impacts their daily quality of life. This group also experiences a significantly higher rate of acute respiratory exacerbations, which are sudden worsening of respiratory symptoms requiring medical intervention.
Long-term studies demonstrate that the PRISm condition is not a benign state, as it is associated with a faster decline in FEV1 over time compared to those with entirely normal lung function. An estimated one-third of individuals diagnosed with PRISm will eventually progress to meet the full spirometric criteria for COPD. Most concerning is the elevated all-cause mortality risk, which is substantially higher in PRISm patients than in healthy controls and approaches the mortality rates seen in patients with established COPD. This heightened risk is driven by both respiratory-related events and a disproportionate increase in non-pulmonary complications.
Systemic Inflammation and Associated Health Issues
The poor long-term outcomes for PRISm patients are largely attributed to the presence of chronic, low-grade systemic inflammation that extends beyond the lungs. This persistent inflammatory state acts as a common link to several non-pulmonary comorbidities. The PRISm phenotype is particularly associated with an increased prevalence of cardiovascular disease (CVD), including conditions like ischemic heart disease and heart failure.
The underlying inflammation may contribute to the accelerated development of atherosclerosis and other vascular issues, explaining the notably high rate of cardiovascular mortality observed in this population. Furthermore, PRISm is linked to metabolic disorders, with a documented association with an abnormal body mass index (BMI), including both obesity and low body weight. Patients are also more likely to experience an accelerated progression of frailty compared to individuals with normal spirometry, emphasizing the systemic nature of the condition. The presence of conditions such as obstructive sleep apnea (OSA) is also more frequent in PRISm, which further complicates the patient’s respiratory and overall health status.
Tailored Management Approaches
The unique physiological profile of PRISm necessitates a management strategy that differs from the standard treatment protocol for established COPD. Since these patients do not have significant airflow obstruction, the traditional use of bronchodilator therapy, a mainstay for COPD, is often less effective or potentially inappropriate. Instead, the treatment approach must focus heavily on mitigating the systemic risks and associated health issues.
The primary intervention is smoking cessation for all individuals with a smoking history, as this is the most impactful action to slow lung function decline and reduce mortality risk. Pulmonary rehabilitation is a highly recommended non-pharmacological intervention, providing structured exercise training and education to improve exercise capacity and manage symptoms like breathlessness. A core component of care involves the aggressive identification and management of comorbidities, especially cardiovascular and metabolic issues, which should be treated according to their specific guidelines. Close monitoring of systemic health markers and a focus on lifestyle changes, including physical activity and nutritional support, are paramount to improving the long-term outlook for those diagnosed with the PRISm phenotype.