Inter-rater reliability of Mechanical Diagnosis and Therapy (MDT) in evaluating and classifying chronic pelvic pain syndrome.

Introduction: Chronic pelvic pain syndrome (CPPS) involves complex interactions between the musculoskeletal system, nervous system, and psychosocial factors. A major challenge in managing CPPS is the lack of reliable assessment and classification systems. The Mechanical Diagnosis and Therapy (MDT) is a widely used and reliable classification system for assessing and managing painful musculoskeletal conditions affecting the spine and extremities. This study's primary objective was to assess the inter-rater reliability of the MDT assessment in diagnosing CPPS using clinical vignettes. Secondary objectives included determining the prevalence of MDT classification categories.

Methods: Five MDT clinicians classified clinical vignettes into three categories: 1) Spinal Derangement, 2) Pelvic Floor Contractile Dysfunction, or 3) MDT OTHER subgroups. The vignettes were developed from the McKenzie Pelvic Pain Assessment Form. Inter-rater reliability among clinicians was calculated using the Fleiss kappa statistic with 95% confidence intervals, and Cohen's kappa examined reliability between pairs of raters.

Results: A total of 76 vignettes were developed (40 females and 36 males). Good inter-rater reliability was found among clinicians (Fleiss kappa = 0.616, 95% CI = 0.598-0.633, p < 0.001). Inter-rater reliability was higher when classifying female vignettes (Fleiss kappa = 0.658, 95% CI = 0.634, 0.682) than male vignettes (Fleiss kappa = 0.546, 95% CI = 0.519, 0.573). The most common classification was Spinal Derangement (57%), followed by MDT OTHER subgroups (26%) and Pelvic Floor Contractile Dysfunction (17%).

Conclusions: The study indicates good inter-rater reliability among MDT clinicians in classifying pelvic pain syndrome. However, clinical vignettes may not fully capture the complexities of real participant interactions, potentially inflating agreement. Future studies should incorporate direct observation of real participant encounters alongside clinical vignettes to improve validity.