Retrospective assessment of cancer pain management in an outpatient palliative radiotherapy clinic using the Pain Management Index

Abstract

Context: The Pain Management Index (PMI) is a simple index linking the usual severity of cancer pain with the category of medication prescribed to treat it. Medication categories are derived from the World Health Organization's "analgesic ladder" approach to cancer pain, and the PMI is an indicator of the extent to which the medication prescribed corresponds to the recommended categories for mild, moderate, and severe pain.

Objectives: The aim of this study was to assess prevalence of inadequate pain management in an outpatient palliative radiotherapy clinic using the PMI.

Methods: All patients with bone metastases referred for palliative radiotherapy from 1999 to 2006 were retrospectively analyzed for patient-rated pain scores (0-10 scale) and analgesic consumption. Pain scores were assigned 0, 1, 2, and 3 when patients reported no pain (0), mild (1-4), moderate (5-6), or severe pain (7-10), respectively. Analgesic scores of 0, 1, 2, and 3 were assigned when patients were prescribed no pain medication, nonopioids, "weak" opioids, and "strong" opioids, respectively. The PMI score was calculated by subtracting the pain score from the analgesic score. A negative PMI score was considered an indicator of potentially inadequate pain management by the prescriber. Descriptive statistics, Pearson's r correlation, and univariate and multivariate logistic regression analysis were used to determine the relationship of PMI over time, and the relationship with predictive factors.

Results: One thousand patients were included from January 1999 to December 2006. A negative PMI was calculated for 25.8% of patients at initial consultation. Prevalence of negative PMI significantly increased over years (P<0.0001). Higher Karnofsky Performance Status (P<0.0001) and breast primary cancer site (P<0.0001) were significantly associated with negative PMI after adjusting for year variable.

Conclusion: Despite publication of numerous cancer pain management guidelines, undermedication appears to be a persistent problem for patients with painful bone metastases referred for radiotherapy.