Background: Symptom clusters have not been previously explored in acute pain patients
(APPs) and chronic pain patients (CPPs) with non-cancer pain.
Objectives: The objectives of this study were to determine in CPPs and APPs which somatic and
non-somatic symptoms cluster with each other, the number of clusters, and if cluster number
and cluster symptom makeup differ by pain level.
Study Design: Study sample was 326 APPs and 341 CPPs who had completed a pool of
questions that had included current symptom questions other than pain. Symptom cluster
analyses were performed on 15 somatic and non-somatic symptoms for APPs and CPPs and for
2 CPP subgroups with moderate and severe pain.
Setting: APPs and CPPs were from rehabilitation facilities located in 30 states in all geographical
regions of the United States.
Results: APPs had 4 symptom clusters and CPPs had 5. For CPPs, the clusters represented
memory, neurological, behavioral, somatic, and autonomic problems. CPPs with moderate
and severe pain had 3 and 4 symptom clusters, respectively, and differed in cluster symptom
constitution.
Limitations: Patients selected themselves for study inclusion and were paid for their
participation. This could have affected random selection. Lastly, we used the current time
definitions of acute pain versus chronic pain (90 days) to separate our patients into these groups.
Currently, no consensus exists regarding the optimal time duration to divide acute from chronic.
Conclusions: APPs and CPPs are characterized by symptom comorbidities that form clusters.
In CPPs, cluster number and cluster symptom makeup are affected by pain level. This has
implications for clinical practice and future research.
Key words: Comorbidity, somatic symptoms, comorbid symptoms, chronic pain patients,
acute pain patients, community patients without pain, clusters, symptom clusters