Concurrent validation of a pressure pain threshold scale for individuals with myofascial pain syndrome and fibromyalgia

Background: Manual pressure palpation is an examination technique used in the classification of myofascial pain syndrome (MPS) and fibromyalgia (FM). Currently, there are no validated systems for classifying results. A valid and reliable pressure pain threshold scale (PPTS) may provide a means for clinicians to grade, document, and report findings. The purpose of this investigation was to validate a PPTS in individuals diagnosed with MPS and FM. Intra-rater reliability, concurrent validity, minimum cut-off value, and patient responses were evaluated.& para;& para;Methods: Eighty-four participants who met the inclusion criteria were placed into three groups of 28 (N= 84): MPS, FM, and asymptomatic controls. All participants underwent a two-part testing session using the American College of Rheumatology criteria for classifying FM. Part-1 consisted of manual palpation with a digital pressure sensor for pressure consistency and part 2 consisted of algometry. For each tender point (18 total), participants graded tenderness using the visual analog scale (VAS) while the examiner concurrently graded response using a five-point PPTS.& para;& para;Results:The PPTS had good intra-rater reliability (ICC >= 88). A moderate to excellent relationship was found between the PPTS and VAS for all groups with the digital pressure sensor and algometer (rho >= .61). A minimum cut-off value of 2 on the PPTS differentiated participants with MPS and FM from asymptomatic controls.& para;& para;Discussion: The results provide preliminary evidence validating the PPTS for individuals with MPS and FM. Future research should further study the clinimetric properties of the PPTS with other chronic pain and orthopedic conditions.