Poor sleep quality — assessed by full-night sleep evaluation and patient questionnaires — is linked to an overall reduced quality of life in individuals with idiopathic pulmonary fibrosis (IPF), according to a study.
The study, “Quality of life in idiopathic pulmonary fibrosis: The impact of sleep disordered breathing,” was published in the journal Respiratory Medicine.
Several factors, such as comorbidities, medication, and depression, contribute to a reduced quality of life in individuals with IPF. Similar to chronic obstructive pulmonary disease (COPD), accumulating evidence suggests that sleep-related disorders may impact IPF prognosis. As a result, obstructive sleep apnea syndrome (OSAS; upper airway obstruction during sleep) was added as a comorbidity in the last American Thoracic Society guidelines for the diagnosis of IPF.
Although patients with IPF often experience sleep-disturbed breathing and poor sleep quality, few studies have assessed the relationship between the two.
In the present study, researchers analyzed sleep patterns and patient questionnaires to evaluate the impact of sleep-related disorders on quality of life in individuals with moderate-to-severe IPF.
The study enrolled 34 IPF patients (mean age of 68.74 years), and divided them into three groups depending on the presence of sleep-disordered breathing, OSAS, and sleep-related hypoxia (oxygen deficiency).
Group A included nine IPF patients without sleep-disordered breathing, group B had 17 IPF patients with OSAS but without sleep-related hypoxia, and group C included eight participants with both OSAS and sleep-related hypoxia.
The team first assessed the patient’s lung function status, including forced vital capacity (%FVC) and diffusion lung capacity for carbon monoxide (%DLCO), and performed a full-night polysomnographic study (a sleep study measuring several parameters).
The patients filled out three questionnaires evaluating excessive daytime sleepiness (Epworth Sleepiness Score), quality of sleep (Pittsburgh Sleep Quality Index), and quality of life (St. George’s Questionnaire).
Analysis of the measured sleep parameters showed no significant differences between the three groups. However, certain sleep parameters showed a worse trend in group C compared with the other groups.
When researchers analyzed participants’ self-reported daytime sleepiness, they found that the general scores were very low (mean score of five; a score of 10 or below is considered normal). However, three participants in group C (8%) scored above normal (score above 10).
In addition, most participants who reported poor quality of sleep belonged to group C (62.5%). Further comparison between polysomnographic measurements and self-reported quality of sleep showed that the number of night-time awakenings was the only significant predictor of sleep quality.
The team then assessed the quality of life of the participants, measured by the St. George’s questionnaire, which ranges from zero (no impairment) to 100 (maximum impairment). They found that quality of life was below the scores of the general population in 50 percent of the IPF participants. Group C had a significantly poorer quality of life (63.95) compared with group A (35.43) and group B (49.47).
Although quality of life scores worsened from group A to group C (with group B being in the middle), further analyses showed that group membership alone did not explain the scores. Researchers found that most of the variability in quality of life was significantly predicted by %FVC, %DLCO, quality of sleep, and excessive daytime sleepiness.
Overall, the results showed that quality of life is affected by sleep quality and IPF-related impairments. Patients with severe sleep-disturbed breathing (OSAS and hypoxia) show poorer quality of life, compared with patients from the other groups.
Based on these observations, researchers said the diagnosis and treatment of sleep-disturbed breathing could significantly improve the quality of life of IPF patients.
They suggested that “clinicians should dedicate greater attention to IPF patients when (sleep-disturbed breathing) is suspected and, in the absence of an effective therapy for IPF, optimizing (quality of life) could become a primary therapeutic goal.”