Factors associated with the rate of FEV1 decline in a primary care COPD population

Abstract

The purpose of this thesis was to describe the rate of forced expiratory volume in 1 second (FEV1) decline in COPD patients seen in primary care and investigate factors associated with the rate to help identify COPD patients who might decline faster and who may benefit from interventions to slow the rate of FEV1 decline. The aims of this research were: i. To describe and explore the rate of FEV1 decline in a primary care COPD population, ii. To investigate the relationship between inhaled corticosteroids (ICS) and rate of FEV1 decline in a primary care COPD population, and iii. To investigate the relationship between the rate of FEV1 decline and future risk of CVD in a primary care COPD population. Firstly, other than increasing age, COPD patients who were current smokers, had low BMI, high mMRC dyspnoea, low baseline FEV1 percent predicted, and more frequent or severe AECOPD were more likely to have accelerated FEV1 decline. Secondly, a systematic review revealed that COPD patients enrolled in randomised control trials (RCTs) treated with ICS had reduced rates of FEV1 decline compared to patients not treated with ICS over short follow-up periods. However, over longer follow-up periods the rate of FEV1 decline in patients in ICS and non-ICS trial arms were similar. In addition, using primary care data, COPD patients who initiated ICS showed an increase in FEV1, notably in patients with high blood eosinophils, compared to patients who were not prescribed ICS however, prevalent ICS users had a clinically similar rate of FEV1 decline compared to those not prescribed ICS, regardless of blood eosinophil level, echoing the findings of the systematic review. Similarly, COPD patients who withdrew from ICS (from triple therapy) showed a similar mean rate of FEV1 decline compared to patients who remained on triple therapy. Thirdly, the rate of FEV1 decline, including accelerated FEV1 decline, was not associated with future risk of CVD disease and mortality in CVD naïve COPD patients. These results suggest that rate of FEV1 decline is heterogeneous and both patient related and disease related characteristics should be monitored to identify COPD patients with faster disease progression earlier. Whilst these patients may not have an increased risk of CVD, it is still important to identify these patients to intervene with better treatments or other possible interventions to reduce the risk of all-cause mortality and other potential morbidities. ICS treatment is a common intervention used to slow the progression of COPD however, results suggest that its long-term use does not significantly slow down the rate of FEV1 decline compared to non-ICS medications, but initiation of ICS treatment does improve FEV1 in the short-term. Proactive identification of fast FEV1 decliners and the implementation of effective interventions in COPD patients by primary care providers may help to improve patient outcomes.Open Acces