Fig. 1
From: Understanding the impact of symptoms on the burden of COPD
a Time of day when COPD symptoms are worse than usual. Reproduced from [17]; b prevalence of any COPD symptoms during each part of the 24-h day, according to COPD severity. Reproduced from [3]. *p < 0.001 vs ‘midday’, ‘afternoon’, ‘evening’, ‘night’, and ‘difficult to say’ groups; p = 0.006 vs ‘no particular time of day’ (all COPD patients); †p < 0.001 vs ‘midday’. COPD chronic obstructive pulmonary disease