Exploration of symptoms clusters within cancer patients with brain metastases using the Spitzer Quality of Life Index

Advanced cancer patients can experience many concurrent symptoms. It has been suggested that certain symptoms can cluster together and have a synergistic effect on patient morbidity. The objective of this study was to explore the presence of symptom clusters in patients with brain metastases treated with whole brain radiotherapy (WBRT). Patients with brain metastases were asked to rate their symptoms and quality of life (QOL) using the Spitzer Quality of Life Index (SQLI) and a study-designed 17-item symptom questionnaire. Utilizing a principal component analysis, the SQLI and symptoms were analyzed for the presence of symptom clusters. The Cronbach's alpha statistic was used to estimate the internal consistency and reliability of the derived clusters. Follow-up was carried out at baseline and 1, 2 and 3 months following WBRT. Between August 2005 to October 2007, 129 patients with brain metastases were enrolled. Analysis of the SQLI items revealed two clusters. Cluster 1 consisted of activity, daily living and health, while cluster 2 consisted of support and outlook. Cronbach's alpha was 0.69 and 0.40, respectively, for the two clusters, which accounted for 64% of the total variance. Analysis of the 17 additional symptoms revealed three clusters at baseline. These clusters changed slightly over time, but certain symptoms appeared to remain together: (1) trouble concentrating and confusion, (2) memory loss and decreased alertness, (3) nausea and vomiting, (4) numbness and weakness, and (5) dizziness and headache. These clusters persisted despite WBRT. Symptom clusters exist in patients with brain metastases. Although the clusters varied over time, they did not weaken or disintegrate following WBRT, suggesting the latter one may not significantly improve the QOL and symptom distress in this group.