The relevance of chronic respiratory symptoms without airflow obstruction: health-related characteristics and impact on patient prognosis

Individuals reporting chronic respiratory symptoms without airflow obstruction (AFO) were originally classified as “at risk” stage (GOLD Stage 0) of Chronic Obstructive Pulmonary Disease (COPD). However, this stage was removed due to lack of evidence regarding its progression to diagnosed COPD. There remain many such individuals in the population, including some already misdiagnosed with COPD despite not meeting required criteria. This thesis aims to clarify the uncertainty around the relevance of “GOLD Stage 0”. There are three systematic reviews examining the risk of developing COPD amongst GOLD Stage 0 patients, their prognosis and the prognostic factors. The independent effect of respiratory symptoms versus AFO on quality of life is examined using data from the Health Survey for England. Baseline data from the Birmingham COPD Cohort Study are used for two cross-sectional analyses, (1) comparing GOLD Stage 0 patients with those recently identified with COPD and (2) examining the characteristics of those “overdiagnosed” with COPD. GOLD Stage 0 patients showed a similar pattern of poor health outcomes to those diagnosed with COPD. Overdiagnosis of COPD was common, particularly among GOLD Stage 0 patients. Obesity and restrictive disease were potential explanations for some overdiagnosed. The presence of chronic respiratory symptoms has a negative impact on patients’ health, regardless of the presence of diagnosed AFO