Original Article
Preliminary Evidence of an Association Between a Functional Interleukin-6 Polymorphism and Fatigue and Sleep Disturbance in Oncology Patients and Their Family Caregivers

https://doi.org/10.1016/j.jpainsymman.2009.12.006Get rights and content
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Abstract

Context

Fatigue and sleep disturbance are common problems in oncology patients and their family caregivers (FCs). However, little is known about factors that contribute to interindividual variability in these symptoms or to their underlying biologic mechanisms.

Objectives

An evaluation was done on whether genetic variation in a prominent proinflammatory cytokine, interleukin-6 (IL-6 c.-6101A>T [rs4719714]), was associated with mean ratings of evening fatigue, morning fatigue, and sleep disturbance, as well as with the trajectories of these symptoms.

Methods

Over six months, participants completed standardized measures of fatigue and sleep disturbance. Linear regression was used to assess the effect of the IL-6 genotype and other covariates on mean fatigue and sleep disturbance scores. Hierarchical linear modeling was used to determine the effect of the IL-6 genotype on symptom trajectories.

Results

Common allele homozygotes reported higher levels of evening fatigue (P = 0.003), morning fatigue (P = 0.09), and sleep disturbance (P = 0.003) than minor allele carriers. Predictors of baseline level and trajectories of evening fatigue included age, gender, and genotype (intercepts) and baseline level of evening fatigue (slope). Predictors of baseline level and trajectories of morning fatigue included age and genotype (intercept) and age and baseline level of morning fatigue (slope). Predictors of baseline level and trajectories of sleep disturbance included age and genotype (intercept) and baseline level of sleep disturbance (slope).

Conclusions

Findings provide preliminary evidence of a genetic association between a functional promoter polymorphism in the IL-6 gene and severity of evening fatigue, morning fatigue, and sleep disturbance in oncology patients and their FCs.

Key Words

Fatigue
sleep disturbance
interleukin-6
genetics
family caregiver
cancer
cytokines
sickness behavior
radiation therapy

Cited by (0)

This research was supported by a grant from the National Institute of Nursing Research (NINR, NR04835). Dr. Aouizerat is funded through the National Institutes of Health Roadmap for Medical Research Grant (K12RR023262). Dr. Dunn is supported in part by funds from the Mount Zion Health Fund. Additional support for Dr. Miaskowski's program of research was provided through unrestricted grants from Endo Pharmaceuticals, PriCara Unit of Ortho-McNeil, Inc., and Purdue Pharma LP.