Cancer pain intensity (PI) fluctuates, but the relationship between pain flares and background pain with respect to pain management is not settled. We studied how flare and background PIs corresponded with treatment results for background cancer pain. Patients admitted to an acute palliative care unit with average and/or worst PI ≥ 1 on the 11-point numeric rating scale were included. Average and worst PI at admission and average PI at discharge were collected. We examined how the difference and ratio between worst and average PI and average PI at admission, were associated with average PI development during hospitalization. Positive differences between worst and average PI at admission were defined as pain flares. Ninety out of 131 patients had pain flares. The reduction in average PI for patients with flares was 0.9 and for those without, 1.9 (p = 0.02). Patients with large worst minus average PI differences reported the least improvement, as did those with large worst/average PI ratios. Patients with pain flares and average PI ≤ 4 at admission had unchanged average PI during hospitalization, while those with pain flares and average PI > 4 experienced pain reduction (2.1, p < 0.001). Large pain flares, in absolute values and compared to background PI, were associated with inferior pain relief.
Keywords: acute palliative care unit (APCU); background pain; breakthrough cancer pain; cancer pain; episodic cancer pain; pain flares; palliative care.