Sundh J, et al. – The prime focus of this research was to study the prevalence, incidence, and risk factors of hypoxic respiratory failure (HRF) in chronic obstructive pulmonary disease (COPD). The prevalence and incidence of HRF were low and was predicted well by more severe air flow limitation and worse health status in patients with COPD. The risk was highest in patients with the Global initiative for Chronic Obstructive Lung Disease (GOLD) stage IV and GOLD groups C or D.