A pilot home study of temporal variations of symptoms in chronic obstructive lung disease

The purposes of this pilot study are to describe the 24-hr patterns of dyspnea, fatigue, and peak expiratory flow rate (PEFR) in patients with chronic obstructive pulmonary disease (COPD) and examine their interrelationships. The repeated-measures design protocol involved 10 patients with moderate to severe COPD who self-assessed dyspnea, fatigue, and PEFR five times a day for 8 days. Circadian rhythms were documented by single cosinor analysis in 40% of the participants for dyspnea, 60% for fatigue, and 60% for PEFR. The 8-day, 24-hr means of dyspnea and fatigue were moderately correlated; 70% of the sample displayed significant correlations. The means of PEFR and both dyspnea and fatigue were weakly negatively correlated. The findings suggest that circadian rhythm in lung function may not be temporally coupled with the circadian rhythm in dyspnea and fatigue in all patients and that the mean self-perceived levels of dyspnea and fatigue are moderately related.