Factors Predicting the Rate of Decline of FEV1 Values in Patients with Chronic Obstructive Pulmonary Disease

Introduction: Chronic obstructive pulmonary disease (COPD) is a progressive condition and a leading cause of morbidity and mortality worldwide. The rate of forced expiratory volume in one second (FEV1) decline is a key prognostic marker. This study aimed to evaluate the impact of demographic, clinical, and therapeutic factors, including respiratory muscle strength and inhaled corticosteroid (ICS) use, on FEV1 decline.Methods: A prospective study was conducted in 2019 at the Clinic for Pulmonology, Clinical Center of Serbia. Fifty patients with stable COPD underwent spirometry, body plethysmography, respiratory muscle strength testing, and laboratory analyses. Demo-graphic and clinical data were collected via questionnaire. All assessments were repeated after six months of regular inhalation therapy.Results: Significant reductions were observed in FEV1, FVC, TLC, PImax, and PEmax. Lower baseline respiratory muscle strength predicted a faster FEV1 decline. Patients in GOLD stage 2 and those with greater hyperinflation exhibited accelerated functional deterioration. Therapy type affected selected parameters: LABA/ICS and LAMA/LABA/ICS regimens significantly reduced residual volume, but not the rate of FEV1 decline. Higher eosinophil counts were associated with a slower reduction in FEV1, suggesting a potential protective effect of ICS.Conclusion: Respiratory muscle strength, hyperinflation, and eosinophil count represent important predictors of COPD progression. Incorporating these parameters into diagnostic and therapeutic algorithms may improve early risk stratification and support indi-vidualized treatment strategies.