title: Differences in symptom clusters identified using occurrence rates versus symptom severity ratings in patients at the end of radiation therapy.
abstract: The purposes of this study were to identify the number and types of symptom clusters using yes/no responses from the Memorial Symptom Assessment Scale, identify the number and types of symptom clusters using severity scores from the Memorial Symptom Assessment Scale, compare the identified symptom clusters derived using severity scores to those derived using occurrence ratings, and evaluate for differences in symptom cluster severity scores between patients with breast and prostate cancer at the end of radiation therapy. Separate exploratory factor analyses were performed to determine the number of symptom clusters based on symptom occurrence rates and symptom severity ratings. Although specific symptoms within each symptom cluster were not identical, 3 very similar symptom clusters (ie, "mood-cognitive" symptom cluster, "sickness-behavior" symptom cluster, "treatment-related" symptom cluster) were identified regardless of whether occurrence rates or severity ratings were used to create the symptom clusters at the end of radiation therapy. However, the factor solution derived using the severity ratings fit the data better. Significant differences in severity scores for all 3 symptom clusters were found between patients with breast and prostate cancer. For all 3 symptom clusters, the patients with breast cancer had higher symptom cluster severity scores than the patients with prostate cancer.
authors.affiliation: School of Nursing, University of California, San Francisco, California 94143-0610, USA.
authors.forename: Esther
authors.initials: E
authors.lastname: Kim
authors.forename: Thierry
authors.initials: T
authors.lastname: Jahan
authors.forename: Bradley E
authors.initials: BE
authors.lastname: Aouizerat
authors.forename: Marylin J
authors.initials: MJ
authors.lastname: Dodd
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Cooper
authors.forename: Steven M
authors.initials: SM
authors.lastname: Paul
authors.forename: Claudia
authors.initials: C
authors.lastname: West
authors.forename: Kathryn
authors.initials: K
authors.lastname: Lee
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Swift
authors.forename: William
authors.initials: W
authors.lastname: Wara
authors.forename: Christine
authors.initials: C
authors.lastname: Miaskowski
mesh_terms: D000203:Activities of Daily Living; D000223:Adaptation, Psychological; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000523:psychology / Q000532:radiotherapy*; D016009:Chi-Square Distribution; D016000:Cluster Analysis; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D055809:Illness Behavior / Q000528:radiation effects*; D015994:Incidence; D017567:Karnofsky Performance Status; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011336:Probability; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000523:psychology / Q000532:radiotherapy*; D011788:Quality of Life; D011832:Radiation Injuries / Q000453:epidemiology; D012720:Severity of Illness Index; D017678:Sex Distribution; D018434:Sickness Impact Profile; D018709:Statistics, Nonparametric