Low appendicular muscle mass and the risk of COPD development in people with PRISm.

Objectives: Preserved ratio impaired spirometry (PRISm) is a heterogeneous condition often accompanied by respiratory symptoms and increased mortality, affecting 5-24% of the general population. However, the prevalence of low muscle mass and related clinical characteristics in PRISm remain unknown. This study aimed to: 1) determine the prevalence of low appendicular skeletal muscle index (ASMI) in individuals with PRISm compared with normal spirometry and COPD; 2) describe characteristics of persons with PRISm with low or normal ASMI; and 3) investigate whether low ASMI in PRISm is associated with COPD development. Methods: In the Rotterdam Study, participants were classified as PRISm, COPD, or normal spirometry. Baseline characteristics and body composition (dual-energy radiograph absorptiometry-derived ASMI) were collected. Low ASMI was defined as <7.0 kg·m Results: Among 5487 individuals, Low ASMI prevalence in PRISm was 8%, and was more common than in normal spirometry (4%). Among individuals with PRISm, 49% developed COPD over time. Compared to individuals with normal spirometry and normal ASMI, individuals with PRISm and low ASMI had a sevenfold higher risk of developing COPD adjusted for sex, age, and smoking. Conclusion: Low ASMI was more prevalent in PRISm compared to normal spirometry. PRISm at baseline and smoking were strongly associated with COPD development, with the highest risk in individuals with PRISm and low ASMI, suggesting that low ASMI in PRISm may be a treatable trait requiring clinical attention.