Study on risk factors and phenotypes of acute exacerbations of chronic obstructive pulmonary disease in Guangzhou, China-design and baseline characteristics.

Abstract

To describe a study design that focuses on risk factors and patterns of chronic obstructive pulmonary disease (COPD) exacerbations. A 2-year, single centre, observational study was conducted in Guangzhou in China. The study enrolled 318 subjects with COPD aged 40-79 years, stratified into different but equally sized groups according to global initiative for chronic obstructive lung disease (GOLD) stage (including Stage 0) and 86 lung healthy controls. An assessment each year was scheduled including questionnaires, lung function testing, Chest X-ray and blood collection. A sub-group, called sub-group X, consisting of 203 subjects with COPD and 51 lung healthy controls, was selected to answer a symptom questionnaire daily (EXACT-PRO) via a BlackBerry Personal Digital Assistant (PDA) device. Upon an alert that indicated a change in daily symptom pattern, the patients were contacted by the clinic to decide whether they had experienced an exacerbation and should have an extra visit within 24-48 hours. At an extra visit, nasal and throat swabs, induced sputum and blood were collected. Air pollution, temperature and humidity were also monitored daily. A subset of sub-group X, called sub-group M that consisted of 52 COPD patients and 15 healthy controls was dedicated to measure muscle strength and a dexa scan. More than 78% of the enrolled patients completed the study successfully. There appeared a difference between the patient groups and the controls in gender, age, body mass index (BMI), forced expiratory volume in 1 second (FEV1), FEV1/FVC and smoking at baseline. In sub-group X 90 out of 203 (44.4%) selected COPD patients developed one or more exacerbations in the 2-year observation period. They were more severe COPD patients according to GOLD stage at study start. On average most exacerbations occurred in the month March and the least number of exacerbations occurred in October. This study with the obtained patient dataset will allow a better insight in many aspects of exacerbations in COPD (e.g., the identification, the risk factors, phenotypes and the biomarkers).