(126) Test-retest agreement of quantitative sensory testing 12 months after breast cancer surgery

Abstract

Quantitative sensory testing (QST) examines psychophysical response to controlled, graded stimuli such as mechanical and thermal thresholds, and allows assessment of nerve damage. In the breast cancer population, 3 studies have used QST to examine persistent pain after breast cancer treatment (PPBCT), suggesting neuropathic pain being a prominent pain mechanism. However, QST reliability and validity has not been described in the postsurgical population. The aim of the present study was to assess 14 days test-retest reliability and variation of QST 12 months after breast cancer surgery. 32 patients were recruited from a larger prospective trial, scheduled for examination with QST 12 months after breast cancer surgery, and reexamined a week later. A standardized QST protocol was performed, including sensory mapping for mechanical, warmth and cold areas of sensory dysfunction, mechanical thresholds using monofilaments and pin-prick, and thermal thresholds including warmth and cold detection thresholds and heat pain threshold. Method reliability was assessed by Bland-Altman plots, descriptive statistics, coefficients of variance and intraclass correlation coefficients. 31 percent of the patients had pain ≥ 4 on a numerical rating scale, at rest, motion or pressure. Bland-Altman plots showed no systematic bias. T-tests showed very small differences on a group level. Variation coefficient was in the range 1 – 15%, and intraclass coeffients (ICC) ranged from 0.356 to 0.847 (moderate to almost perfect agreement). Between-subject variation (0.9 to 14.5 SD) was generally higher than within subject variation (0.23 to 3.55 SD).12 months after breast cancer surgery, our QST protocol showed moderate to perfect agreement (ICC), and low within subject variability. Thus, the protocol reliability allows for individual follow up and group-to-group comparison of sensory function.