Abstract

Background Given the prevalence of musculoskeletal pain worldwide, there is a growing need to closely examine pain measurement methods. Quantitative sensory testing such as the Pain Pressure Threshold (PPT), still are considered novel approaches to pain assessment offering potential benefits for both research and clinical practice. Purpose To analyze the reliability of a PPT protocol applied in a randomized pragmatic controlled trial among a population of office workers (NCT05790837). Methods A protocol to measure the PPT was designed to assess musculoskeletal symptoms in a two-arm randomized pragmatic controlled trial. The reliability analysis was made for the PPT measurements at baseline before randomization. The PPT protocol considered a script of indications prior to the assessments and a digital algometer (Wagner-Force-Ten-FDX-25). The measurements were made on the neck, elbow and a reference point (lower leg) on both sides of the body in a supine position at a rate of 1 kgf/s of continuous pressure. Three measurements were made on each site with a 30 second period between them. The interclass correlation coefficient (ICC) was calculated for an intrarater reliability (Model 3, k), from which the standard error measurement (SEM) and the minimal detectable change (MDC) at 95% confidence level were subsequently calculated. The protocol took 15-minutes on-average and was carried out by two professional physical therapists. A 95% confidence interval (CI) was calculated for the ICC. RStudio (R version 4.3.3) was used for all the statistical analysis. Results One-hundred and two subjects were measured (average age;45, sd;11,2). The reliability analysis demonstrated excellent intrarater reliability in the neck (ICC = 0.93; CI: 0.90-0.95), elbow (ICC = 0.91; CI: 0.87-0.94), and reference (ICC = 0.93; CI: 0.89-0.95). The SEM was 0.26kgf for the neck, 0.32kgf for the elbow, and 0.45kgf for the reference. The MDC was 0.73kgf for the neck, 0.88kgf for the elbow, and 1.24kgf for the reference. Conclusion(s) The presented PPT measurement protocol proves to be reliable with an excellent ICC for an intrarater reliability and a feasible assessment for musculoskeletal symptoms in a real-world setting for office-workers. Implications This protocol can be considered for measurement in randomized controlled trials and has potential advantages for application in clinical settings and occupational health assessments. The PPT measurement represents a hybrid test for pain, due to its self-reported and quantitative interval data, and could therefore be useful for exploring other components of pain. Scripted verbal instructions explaining the procedure related to the definition of pain seems to be a key component to the study results.