Rate of Forced Expiratory Volume in One Second and Forced Expiratory Volume in One Second/Forced Vital Capacity Decline among Indonesian Patients with Chronic Obstructive Pulmonary Disease after a Year of Treatment

BACKGROUND: The rate of decline in lung function in chronic obstructive pulmonary disease (COPD) patients showed more profound decline than normal individuals. However, a 1-year lung function among Indonesian patients with COPD has not been elucidated. AIM: This study attempted to determine the rate of lung function decline in terms of obstruction variable among COPD patients after a 1-year of treatment. MATERIALS AND METHODS: This retrospective cohort study measures the rate of decline in forced expiratory volume in 1 s (FEV1) and ratio of FEV1 to forced vital capacity (FEV1/FVC) in COPD patients at COPD Outpatient Clinic Persahabatan Hospital after 1-year of treatment. RESULTS: There were 31 COPD patients with the prevalence of 1-year declined FEV1 and FEV1/FVC which were 83.9% and 51.6%, respectively. Among 1-year declined lung function group, there were significant (P < 0.05) decline in FEV1 (121.53 ± 120 ml/year) and in FEV1/FVC (2.75 ± 0.47%). The rate of decline in FEV1 was more prevalent in Group D, while the rate of decline in FEV1/FVC was more prevalent in Group B. No significant associations were found between sex, age, respiratory complaints, smoking history, Brinkman index, type of cigarette, comorbid, educational level, diagnosed age, body mass index, symptoms-based COPD classification, and risk-based COPD classification, with the rate of decline in FEV1 and FEV1/FVC. CONCLUSIONS: Most patients had statistically significant rate of decline in FEV1 and FEV1/FVC within 1-year of COPD treatment. This study recognized an unfavorable prognosis in terms of irreversible deteriorating lung function of COPD patients despite therapeutic management.