An analysis of the variability of breakthrough pain intensity in patients with cancer.

Background: The management of breakthrough pain in patients with cancer (BTPc) generally includes an initial titration of breakthrough pain medication to an effective dose, followed by the use of that dose in all subsequent episodes. This strategy presumes that an individual patient has a degree of consistency of pain during repeat episodes; however, that presumption has not been formally assessed.

Objective: To examine the variation in pain intensity of BTPc episodes within individual patients and across patients.

Methods: Data were pooled from 2 randomized, double-blind, crossover studies that used fentanyl pectin nasal spray (FPNS) vs comparator to relieve BTPc. Eligible patients were adults with an Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2 and adequately controlled background pain. The FPNS dose was titrated prior to a double-blind treatment consisting of 10 episodes. Pain intensity was reported on an 11-point numeric scale in which 0 = no pain and 10 = worst possible pain. Inter- and intrapatient variabilities of baseline pain intensity scores per episode were analyzed by analysis of covariance via a mixed-effect model. The influences of demographics and ECOG grade at study entry were assessed.

Results: Mean baseline pain intensity score was 7.3 (standard deviation, 1.76; range, 2-10) across 1,399 BTPc episodes in 152 patients. The interpatient variability of baseline pain intensity scores was 75.96%; intrapatient variability was 20.64%. Fixed terms for demographics and ECOG grade did not significantly influence baseline pain intensity score (≤ 5% level).

Limitations: This was a post hoc analysis.

Conclusions: Baseline pain intensity scores during episodes of BTPc vary widely between patients, but vary little within individual patients; this supports the use of a consistent maintenance dosage of analgesia for BTPc, once it has been titrated to an effective dose.

Funding/support: The study was funded by Archimedes Development Ltd.