Severe Fatigue Common in Patients With IPF, Pulmonary Sarcoidosis, Study Suggests

Severe fatigue is common among people with idiopathic pulmonary fibrosis (IPF) and pulmonary sarcoidosis, and is associated with worse shortness of breath, depression, catastrophizing, and quality of life, a new study suggests.

The study, “Severe Fatigue is Highly Prevalent in Patients with IPF or Sarcoidosis,” was published in the Journal of Clinical Medicine.

IPF and pulmonary sarcoidosis are interstitial lung diseases (ILDs) characterized by scarring in the lungs. Fatigue — a feeling of tiredness or exhaustion — is a commonly reported symptom of ILDs. However, the exact prevalence of severe fatigue and its associated factors is unclear among these patients.

In the new study, researchers evaluated fatigue in 117 people with ILDs followed at the Zuyderland Medical Centre Heerlen in the Netherlands. The group included 59 people with IPF, and 58 people with pulmonary sarcoidosis. The study group was 62% male, and the median age was 66 years. Most had completed at least high school (64%), and had a history of smoking (59%).

Fatigue was measured with a validated questionnaire called the Checklist Individual Strength-Fatigue (CIS-Fat). Scores ranged from 8 to 56 points: a score of 26 or less is considered normal fatigue, a score from 27–35 indicates mild fatigue, and a score above 35 represents severe fatigue. Other validated questionnaires were used to assess factors such as mental health, shortness of breath, and quality of life. Individual medical data were also analyzed.

Results showed that the mean CIS-Fat score in the group was 37 points, and 58% of participants had a score of 36 or more (indicating severe fatigue). Severe fatigue was present in 28 (48%) participants with IPF, and in 40 (69%) participants with sarcoidosis. The average CIS-Fat score was significantly higher among those with sarcoidosis (40) than IPF (34.1).

“This study clearly shows that severe fatigue was present in a substantial proportion of patients with ILD,” the researchers wrote.

Although fatigue and sleepiness are often conflated, they are different phenomena — fatigue refers to overall exhaustion, and sleepiness means a desire for sleep.

Daytime sleepiness was measured with the Epworth Sleepiness Scale (ESS), which ranges from 0 to 24 points. Interestingly, excessive daytime sleepiness (ESS score of 11 or higher) was much less common than severe fatigue in the overall group (8% vs. 58%). This “suggests poor sleep quality may not be the main driver of severe fatigue in ILD patients,” the researchers wrote.

The team then constructed statistical models to look for patient factors that were significantly associated with CIS-Fat scores.

In both IPF and sarcoidosis patients, high CIS-Fat scores were significantly correlated with worse shortness of breath (as measured by the modified Medical Research Council Dyspnea Scale), anxiety and depression symptoms (assessed by the Hospital Anxiety and Depression Scale), quality of life (measured by the Quality-of-Life for Respiratory Illness Questionnaire), and overall health status (assessed with the EuroQol five-dimensional descriptive system).

Another factor that was significantly associated with fatigue was the tendency to catastrophize (jump to the worst conclusion possible), which was measured with the fatigue catastrophizing scale.

“The relation of catastrophizing to fatigue has not been investigated before in patients with ILD,” the researchers wrote, noting that “catastrophizing can influence the experience of fatigue and seems to be a good predictor of fatigue severity.”

This study was not designed to identify cause-and-effect relationships, but to show correlations (statistical associations). Nonetheless, identifying these related factors may help medical personnel to better manage the care for people with ILDs.

“In clinical management of patients with ILD, it is recommended to assess fatigue, catastrophizing thoughts, and causal attributions of fatigue, because these elements together with dyspnea [shortness of breath] are related to the functional impairments in activities of the patients,” the researchers concluded.