Reliability of the mechanical diagnosis and therapy system in patients with spinal pain: a systematic review

Background: An updated summary of the evidence for the reliability of the Mechanical Diagnosis and Therapy (MDT) system in patients with spinal pain is needed. Objective: To investigate the evidence on the intrarater and interrater reliability of MDT in patients with spinal pain. Methods: Searches in MEDLINE, CINAHL, Embase, PEDro, and Scopus were conducted for this systematic review. We included any study design as long as reliability of the MDT method was tested in patients with spinal pain. We collected data on the reliability of MDT to identify main and subsyndromes, directional preference, the centralization phenomenon, and lateral shift. The methodological quality of studies was assessed using the Quality Appraisal of Diagnostic Reliability and the Guidelines for Reporting Reliability and Agreement Studies checklists. Results: Twelve studies were included (8 studies on back pain, pooled n = 2160 patients; 3 studies on neck pain, pooled n = 45 patients; and 3 studies recruited mixed spinal conditions, pooled n = 389 patients). Studies investigating patients with back pain reported kappa estimates ranging from 0.26 to 1.00 (main and subsyndromes), 0.27 to 0.90 (directional preference), and 0.11 to 0.70 (centralization phenomenon). Kappa estimates for studies investigating neck pain ranged from 0.47 to 0.84 (main and subsyndromes) and 0.46 (directional preference). In mixed populations, kappa estimates ranged from 0.56 to 0.96 (main and subsyndromes). Conclusion: The MDT system appears to have acceptable interrater reliability for classifying patients with back pain into main and subsyndromes when applied by therapists who have completed the credentialing examination, but unacceptable reliability in other therapists. We found conflicting evidence regarding the reliability of the MDT system in patients with neck pain or mixed pain locations.