Inflammatory Markers and Fatigue in Individuals With Moderate to Severe Chronic Obstructive Pulmonary Disease

Background Fatigue, a prevalent complex symptom among patients with chronic obstructive pulmonary disease (COPD), is considered an important clinical indicator of disease severity. However, the underlying mechanisms of COPD-related fatigue are not fully understood. Objectives This analysis explored the relationships between peripheral inflammatory markers and COPD-related fatigue in people with moderate to severe COPD. Methods This is a secondary analysis of a longitudinal observational study of individuals with COPD examining the biological causes and functional consequences of depression. The data used in this study were collected at baseline. Systemic inflammation markers included C-reactive protein (CRP) and three pro-inflammatory cytokines consisting of interleukin-6 (IL-6), IL-8, and tumor necrosis factor-α. COPD-related fatigue was self-reported using the Chronic Respiratory Questionnaire. Covariates included age; gender; smoking status; disease severity; symptoms of depression, anxiety, and pain; and social support. Multivariable linear regression analyses were conducted. Results The sample included 300 adults living with COPD; 80% were male, and the average age was 67.6 years. Modest correlations were found between two systemic inflammatory markers (CRP and IL-8) and COPD-related fatigue. CRP was the only inflammatory marker significantly associated with fatigue symptoms after adjusting for covariates in multivariable analyses. Depression, pain, and education level were also significant predictors of COPD-related fatigue. Discussion The findings suggest that altered immune response based on CRP may contribute to COPD-related fatigue. Management of depression and pain may work as an effective treatment strategy for COPD-related fatigue. Further longitudinal studies with a broader range of inflammatory markers and multidimensional measures of fatigue symptoms are warranted.

An Evaluation of the Multifactorial Model of Cancer-Related Cognitive Impairment

Background Up to 45% of patients report cancer-related cognitive impairment (CRCI). A variety of characteristics are associated with the occurrence and/or severity of CRCI. However, an important gap in knowledge of risk factors for CRCI is the relative contribution of each factor. The multifactorial model of cancer-related cognitive impairment (MMCRCI) is a conceptual model of CRCI that can be used to evaluate the strength of relationships between various factors and CRCI. Objectives The purpose of this study was to use structural regression methods to evaluate the MMCRCI using data from a large sample of outpatients receiving chemotherapy (n = 1,343). Specifically, the relationships between self-reported CRCI and four MMCRCI concepts (i.e., social determinants of health, patient-specific factors, treatment factors, and co-occurring symptoms) were examined. The goals were to determine how well the four concepts predicted CRCI and determine the relative contribution of each concept to deficits in perceived cognitive function. Methods This study is part of a larger, longitudinal study that evaluated the symptom experience of oncology outpatients receiving chemotherapy. Adult patients were diagnosed with breast, gastrointestinal, gynecological, or lung cancer; had received chemotherapy within the preceding 4 weeks; were scheduled to receive at least two additional cycles of chemotherapy; were able to read, write, and understand English; and gave written informed consent. Self-reported CRCI was assessed using the attentional function index. Available study data were used to define the latent variables. Results On average, patients were 57 years of age, college educated, and with a mean Karnofsky Performance Status score of 80. Of the four concepts evaluated, whereas co-occurring symptoms explained the largest amount of variance in CRCI, treatment factors explained the smallest amount of variance. A simultaneous structural regression model that estimated the joint effect of the four exogenous latent variables on the CRCI latent variable was not significant. Discussion These findings suggest that testing individual components of the MMCRCI may provide useful information on the relationships among various risk factors, as well as refinements of the model. In terms of risk factors for CRCI, co-occurring symptoms may be more significant than treatment factors, patient-specific factors, and/or social determinants of health in patients receiving chemotherapy.