ABSTRACT
OBJECTIVE: To identify the association between Quality Of Life (QOL) and pain intensity, and the magnitude of change of pain scores that have a clinically significant impact on patients' QOL. DESIGNS: Multi-center; prospective cohort study. MATERIAL AND METHOD: Patients suffering from cancer pain were recruited from seven university hospitals and three tertiary care centers in Thailand. The FACT-G and the Brief Pain Inventory were used to assess QOL and cancer pain severity, respectively, at study entry and at two-week follow-up. RESULTS: Five-hundred-and-twenty patients were recruited with a mean age of 52. The majority (76%) reported two sites of pain with 80% being treated at either step 2 or 3 (WHO guidelines of pain management). After two weeks, the average level of maximum pain was reduced from 6.6 to 4.8 (mean difference = -1.8, p < 0.001) and the QOL was improved from 58.6 to 61.0 (mean difference = 2.4, p < 0.001). There was a high correlation between the average change of pain intensity and QOL scores (rs = -0.42, p < 0.001). The results show that changes of pain scores of at least three points (3 out of 10) were required for a minimal important difference of FACT-G scores, indicating a significant change on patients' QOL. Pain deterioration had slightly more impact on QOL than pain improvement. A 3-point pain deterioration impaired QOL 10.3 points while 3-point reduction increased QOL only 7.6 points. CONCLUSION: The present findings suggest the importance of pain management. The change of pain scores of at least three points (out of 10 points) had statistical and clinical significance to patients' QOL.