Effects of de-escalated bisphosphonate therapy on the Functional Assessment of Cancer Therapy-Bone Pain, Brief Pain Inventory and bone biomarkers.

Background: The Brief Pain Inventory (BPI) and Functional Assessment of Cancer Therapy-Bone Pain (FACT-BP) are commonly used measures of patient reported pain outcomes. We report on the performance of the FACT-BP in comparison to the BPI within a small, randomized trial.
Methods: Patients with biochemically defined low risk bone metastases were randomized to 4 weekly (control arm) or 12 weekly (de-escalating arm) pamidronate for 1 year. FACT-BP, BPI and serum markers of bone turnover were recorded at baseline and weeks 12, 24, 36 and 48. Mixed effects models were used to compare scores over time between arms. Correlation coefficients were calculated to evaluate the association between FACT-BP and BPI scores, as well as with markers of bone turnover.
Results: Nineteen patients were randomized to each study arm. Pain scores determined by the two instruments were moderately to highly correlated with each other. Baseline C-telopeptide (CTx) level was correlated with baseline FACT-BP and BPI scores. Baseline bone-specific alkaline phosphatase showed a non-significant association with pain scores. There were no correlations between the markers of bone turnover and pain scores at week 12.
Conclusions: In the current study the FACT-BP and BPI correlated well with each other, and with baseline CTx. The possibility of linking subjective pain scores with objective biomarkers of response requires more investigation.