Intra-and inter-patient variability of baseline pain intensity scores during breakthrough pain in cancer.

Abstract

e19578 Background: Breakthrough pain in cancer (BTPc) can be assessed using a patient-reported 11-pt pain intensity (PI) scale (0=no pain; 10=worst possible pain). Little information has been reported about variation of PI between episodes and between individuals. This analysis examined intra- and inter-patient variation in baseline PI scores among patients participating in BTPc clinical trials. Methods: This was a pooled analysis of data from 2 randomized, double-blind, crossover studies that treated BTPc with fentanyl pectin nasal spray (Lazanda®, PecFent®) compared with placebo or with morphine sulfate immediate release. Patients were adults with ECOG score ≤2 who experienced BTPc despite background pain that was adequately controlled with ≥60mg morphine (or equivalent). Each study included dose titration prior to the double-blind treatment phase of 10 episodes of BTPc. Inter- and intra-patient variability of baseline pain scores for each episode were analyzed by ANCOVA using a mixed-effect model. Influence of covariables including demographics and ECOG score at study entry was assessed. Results: A total of 152 patients had 1399 BTPc episodes assessed. Mean (SD) age was 54.2 (12.0) yr; 81 patients (53%) were men. The mean ± SD episode baseline PI score was 7.3 ± 1.76 (range 2-10). Inter-patient variability of baseline PI scores was 75.9% and between-study variability, 3.5%; intra-patient variability among the 152 patients was 20.6%. Fixed terms for demographics and ECOG score were not significant factors influencing baseline PI scores at or below the 5% level. Conclusions: This analysis demonstrates that BTPc episodes have large variations in baseline PI scores between patients and that these scores are not influenced by demographics or ECOG score (0-2). However, individual patients show comparatively low variability in baseline PI scores between BTPc episodes. This supports the use of a consistent maintenance dose of an analgesic agent once it has been titrated to an effective dose.