This presentation will focus on the conceptual issues of defining a symptom cluster, proposing relationships between and among component symptoms, and considering the potential effects of intervention on the cluster and its components. Each of these conceptual issues has implications for study design, measurement, and data analysis.
There are many questions that need to be addressed with regard to symptom clusters. First, is "symptom cluster" the correct term to describe the phenomenon of interest? Webster's Third New International Dictionary (1986) defines a cluster as a set of concurrent things considered as a group because of their relation to each other, their simultaneous occurrence, or for convenience of discussion. Other terms might be considered to name this phenomenon including syndrome, constellation, or profile. Each of these terms will be discussed.
Second, what symptoms should be considered to form a cluster? In this presentation, we consider the potential cluster of fatigue, insomnia, pain, and depression. Fatigue is the most common and distressing symptom reported by individuals undergoing cancer treatment making it a logical place to start. Recent findings have documented the co-existence of fatigue and several other common symptoms in cancer patients undergoing treatment including insomnia, pain, and emotional depression.
Third, what is the nature of the relationship between and among this cluster of symptoms? Studies have documented a correlation between fatigue and insomnia, but there is also evidence suggesting that insomnia could be a cause of fatigue in cancer patients. Other research suggests that pain and fatigue have a synergistic relationship with one another, each increasing in the presence of the other. Fatigue and depression have been documented as concurrent symptoms in cancer patients. However, at least one study concluded that fatigue and depression were independent conditions that did not have a causal relationship.
Fourth, what is optimal management of a symptom cluster? The management of a symptom cluster may differ from the management of an individual symptom. If insomnia causes fatigue and pain exacerbates it (as suggested by some research), it is possible that fatigue could be reduced or eliminated by managing these other symptoms. However, the use of opioid drugs to manage pain could have the unintended effect of increased fatigue. Well-controlled intervention studies are needed to examine the consequences on the symptom cluster of managing one or more symptoms in the cluster.
Back to Symptoms as Clusters
Back to The Advancing Nursing Practice Excellence: State of the Science