Quantitative-qualitative analyses of patient-reported pain response after palliative radiation therapy

Purpose While the 0-10 pain scale is often used to assess treatment response, it may not accurately reflect change in pain over time. The purpose of this study is to correlate pain improvement using the 0-10 pain scale to patients' perceived improvement in pain following palliative radiation therapy (RT), and to qualitatively characterize themes of pain assessment. Methods Patients age >= 20 receiving RT for spinal metastases were enrolled. Patients rated their pain (0-10) at the treatment site at RT start, and 1 and 4 weeks post-RT completion. At 1 and 4 weeks post-RT, patients reported their perceived percent improvement in pain (pPIP) (0-100%), which was compared to calculated percent improvement in pain (cPIP) based on the 0-10 pain scores. At 4 weeks post-RT, 20 randomly selected patients participated in a qualitative pain assessment. Results Sixty-four patients treated at 1-2 sites were analyzed. At 1 week post-RT completion, 53.7% (36/67) reported pPIP within 10 percentage points of cPIP, 32.8% (22/67) reported pPIP > 10 percentage points higher than cPIP, and 13.4% (9/67) reported pPIP > 10 percentage points lower than cPIP. Similar degrees of discordance were seen at 4 weeks post-RT. Qualitative analysis revealed five themes: pain quality (n = 19), activities (n = 9), function (n = 7), medication use (n = 2), and radiation side effects (n = 1). Conclusions About half of patients reported a pPIP substantially disparate from their cPIP, and the change in pain measured by the 0-10 scale tended to underestimate the degree of perceived pain improvement. Multiple themes were identified in qualitative analysis of pain response.