Validation of Symptom Clusters in Patients with Metastatic Bone Pain

[摘要] Purpose: Symptom clusters (SC) are a dynamic construct that consist of at least two or three interrelated symptoms that may be a significant predictor of patient morbidity. In a previous study, we identified two symptom clusters in patients with bone metastases: 1) an activity-related; and 2) a psychological-related interference factor. These SCs may be clinically important in the pain and symptom management of these patients with metastatic bone pain. It is therefore important to validate the reported SC to determine if they stand true across similar patient populations. Materials/Methods: From February to September 2007, 52 patients with bone metastases referred for palliative radiotherapy (RT) were accrued into this study. There were 29 males (56%) and 23 females (44%), with a median age of 68.5 years (range 39-87). Prostate (31%), breast (29%) and lung (19%) were the most common primary cancer sites. Treatment arms ranged from single to multiple fractions, with the majority of patients receiving a single 8Gy (77%) and 20Gy/5 (21%). The most prevalent sites of RT were to the spine (42%), hips (17%) and pelvis (14%). Worst pain at the site of RT and functional interference scores were assessed using the Brief Pain Inventory (BPI), a multidimensional pain instrument that uses 11-point numerical rating scales. Patients provided their symptom severity scores on the BPI at baseline, 4, 8 and 12 weeks post-RT. A principal component analysis with "varimax rotation" was performed on the 8 items (worst pain and 7 functional interference items) at all time points to determine interrelationships between symptoms, before and after RT of bone pain. Results: Two clusters were identified. Cluster 1 included worst pain, interference with general activity, normal work and walking ability, whereas Cluster 2 consisted of interference with mood, sleep, enjoyment of life and relations with others. Our statistical analysis produced varied results from the two clusters found in our previous investigation. These differences may be an indicator for the instability of symptom clusters or may be attributed to the fewer number of patients in the present validation study.Conclusion: The symptom clusters were not identical in the two studies with patients receiving palliative RT for their symptomatic bone metastases. It is advised to conduct another symptom cluster validation study with a larger sample, before concluding the existence of an unstable phenomenon in symptom cluster research.

[学科分类] 肿瘤学