A two-point estimation (TPE) task was associated with greater reliability than commonly used approaches (eg, two-point discrimination threshold, body image drawings) for the assessment of sensory dissociation (SEDI) in patients with chronic low back pain, according to a study published in Pain Medicine.

A total of 32 patients treated for chronic low back pain (lasting >6 months) at an orthopedic rehabilitation department were asked to perform the manual and verbal versions of the TPE. In the manual version, participants were asked to estimate the distance between tactile stimuli that were administered to the back using 2 mechanical callipers. For the verbal version of the TPE participants were asked to verbally report this estimated distance.

Inter-examiner reliability for evaluating SEDI was found to be higher with the manual vs verbal version of TPE. The mean of the 2 repeated measurements had excellent reliability for both pain-free (intraclass correlation coefficient [ICC], 0.91; 95% CI, 0.77-0.97) and painful (ICC, 0.86; 95% CI, 0.65-0.94) sides. Intra-examiner reliability of the manual TPE was found to be moderate to excellent for both the painful and the pain-free sides (ICC, 0.66-0.96). Significant predictors for SEDI included pain distribution, duration, and intensity, which accounted for 42% of the total variance (corrected R², 0.42; P <.01).

Study limitations include its non-randomized non-blinded not placebo-controlled design, as well as the small cohort.

“Pain-related variables affect TPE scores and provide the first data supporting the construct validity of this new test. TPE is a novel tool characterized by higher reliability coefficients compared with tools described in literature and can therefore be used clinically and experimentally by one or more examiners,” concluded the study authors.

Two-Point Estimation Task May Reliably Assess Sensory Dissociation in Chronic Low Back Pain

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