An exploration of symptom clusters, symptoms, and blood-based biomarkers in people with cystic fibrosis during an acute pulmonary exacerbation

Cystic Fibrosis (CF) is the most common life-shortening genetic disorder. People with CF experience frequent symptoms, such as cough, difficulty breathing, and fatigue. When these symptoms worsen, people with CF are often diagnosed with a pulmonary exacerbation (PEx). Each PEx diagnosis, people with CF are at risk for complications, such as permanent decline in lung function. Therefore, the purpose of this study was to improve our understanding of symptoms that occur during a PEx through symptom cluster, symptom burden, and biomarker research.
K-means clustering analysis was used to test how symptoms cluster on Day 1, Day 7, Day 14 and Day 21 of a PEx. Regression models were created to test if symptom clusters can predict failure to return to baseline lung function and length of hospitalization, and if symptom burden can predict failure to return to baseline lung function. Correlational analyses were used to test the relationships between symptoms, C-reactive protein (CRP) and interleukin-6 (IL-6).
Symptoms significantly cluster based on severity on Day 1 and Day 7 of a PEx. Symptom clusters on Day 1 significantly predicted that people in the high symptom severity cluster spent significantly more nights in the hospital than the low symptom severity cluster. Symptom burden significantly predicted failure to return to baseline lung function, and people with a symptom burden 1 standard deviation from the mean were 12.34% more likely to not recover to baseline lung function by Day 10-21. It was discovered that symptom burden, increased mucus, and chills/sweats significantly correlated with CRP at Visit 1, Day 1-2 of PEx, and Visit 3, 2 weeks post-hospitalization. Chills/sweats and feeling feverish significantly correlated with IL-6 at Visit 1, and symptom burden, fatigue, and increased mucus significantly correlated with IL-6 at Visit 3. This study successfully discovered symptom clustering patterns in people with CF, and conveys the usefulness of symptom clusters and symptom burden in predicting healthcare outcomes. Findings from this study provide preliminary evidence that inflammatory markers and symptoms correlate at the beginning and end of a PEx. This study improves our understanding of symptoms that occur during a PEx.