Determinants of pain severity changes in ambulatory patients with cancer: an analysis from Eastern Cooperative Oncology Group trial E2Z02.

Purpose: To understand changes in pain severity over time and to explore the factors associated with pain changes in ambulatory patients with solid tumors.
Patients and Methods: We enrolled 3,106 patients with invasive cancer of the breast, prostate, colon/rectum, or lung from multiple sites. At baseline and 4 to 5 weeks later, patients rated their pain level on a 0 to 10 numerical rating scale. A 2-point change in pain score was defined as a clinically significant change in pain. Multivariable logistic models were fitted to examine the effects of pain management and demographic and clinical factors on change in pain severity.
Results: We analyzed 2,761 patients for changes in pain severity. At initial assessment, 53.0% had no pain, 23.5% had mild pain, 10.3% had moderate pain, and 13.2% had severe pain. Overall, one third of patients with initial pain had pain reduction within 1 month of follow-up, and one fifth had an increase, and the improvement and worsening of pain varied by baseline pain score. Of the patients without pain at initial assessment, 28.4% had pain (8.9% moderate to severe) at the follow-up assessment. Logistic regression analysis showed that inadequate pain management was significantly associated with pain deterioration, as were lower baseline pain level, younger age, and poor health status.
Conclusion: One third of patients have pain improvement and one fifth experience pain deterioration within 1 month after initial assessment. Inadequate pain management, baseline pain severity, and certain patient demographic and disease characteristics are associated with pain deterioration.