Intra-Examiner and Between-Day Reliability of Algometer for Pressure Pain Threshold and Pain Sensitivity in Upper Trapezius Muscle in Asymptomatic Young Adult Women

Assessment of pain sensitivity, as an important criterion, is used in diagnosis of musculoskeletal impairments, which helps determine prognosis as well as the improvement rate after treatment interventions. Regarding the costs of modalities and treatment equipment used to reduce pain, having a reliable method to determine their efficacy is essential. The aim of the present study was to evaluate intra-examiner and between-day reliability of an accessible digital algometer to assess pressure pain threshold and for pain sensitivity for the first time. A total of 15 healthy young adult women aged 18-30 participated in the study. Three points of upper Trapezius muscle in both sides were tested in 3 repetitions with 30 seconds rest interval. The tests included PPT by controlled speed of increasing pressure and Visual Analogue Scale to evaluate local pain elicited by exertion of 2.5 kg/cm2 of pressure on the marked point. Trials were conducted on two consecutive days. Intra Class Correlation, Coefficient Standard Error of Measurement, and Minimal Detected Change were calculated to analyze the reliability of the measurements. Assessments revealed high to moderate intra-examiner reliability for pressure pain threshold (ICC>0.972) and pain sensitivity (ICC>0.707) and high to moderate between-day reliability for pressure pain threshold (ICC>0.974) and pain sensitivity (ICC>0.676). Although pressure algometer has an acceptable intra-examiner and between-day reliability for estimating the pressure pain threshold and pain sensitivity, a significant decrease was revealed in the mean values of PPT and increase in PS on the second day, as compared to that on the first day, (P<0.05) which could be related to local tissue trauma, learning effect, or central sensitization.