Development and performance of a diagnostic/prognostic scoring system for breakthrough pain.

OBJECTIVES: Variable prevalence and treatment of breakthrough pain (BTP) in different clinical contexts are partially due to the lack of reliable/validated diagnostic tools with prognostic capability. We report the statistical basis and performance analysis of a novel BTP scoring system based on the naïve Bayes classifier (NBC) approach and an 11-item IQ-BTP validated questionnaire. This system aims at classifying potential BTP presence in three likelihood classes: "High," "Intermediate," and "Low."

METHODS: Out of a training set of n=120 mixed chronic pain patients, predictors associated with the BTP likelihood variables (Pearson's χ(2) and/or Fisher's exact test) were employed for the NBC planning. Adjusting the binary classification to a three-likelihood classes case enabled the building of a scoring algorithm and to retrieve the score of each predictor's answer options and the Patient's Global Score (PGS). The latter medians were used to establish the NBC thresholds, needed to evaluate the scoring system performance (leave-one-out cross-validation).

RESULTS: Medians of PGS in the "High," "Intermediate," and "Low" likelihood classes were 3.44, 1.53, and -2.84, respectively. Leading predictors for the model (based on score differences) were flair frequency (ΔS=1.31), duration (ΔS=5.25), and predictability (ΔS=1.17). Percentages of correct classification were 63.6% for the "High" and of 100.0% for either the "Intermediate" and "Low" likelihood classes; overall accuracy of the scoring system was 90.9%.

CONCLUSION: The NBC-based BTP scoring system showed satisfactory performance in classifying potential BTP in three likelihood classes. The reliability, flexibility, and simplicity of this statistical approach may have significant relevance for BTP epidemiology and management. These results need further impact studies to generalize our findings.