Interrater reliability and diagnostic accuracy of pelvic girdle pain classification.

The purpose of this study was to measure the reliability of a classification system for pelvic girdle pain (PGP) and diagnostic accuracy of selected examination and clinical special findings for diagnosis of PGP. The design involved a prospective epidemiological study of pregnancy-related PGP. Consecutive subjects were recruited and classified using criteria defined by previous studies. Two clinicians examined the subjects and classified each patient into 1 of 5 classification groups. Clinical examination and clinical special tests were performed on the patients with PGP. Statistical analysis involved interobserver agreement using a kappa statistic and sensitivity and specificity values for the examination and clinical special testing. Twenty-one subjects were included in the analyses. Aggregated percentage of agreement for the classification system was 84.6%. The Cohen kappa was 0.78 (CI, 0.64-0.92; P < .0001), which indicated substantial agreement during selection of the classification system. Most clinical examination and clinical special-test findings demonstrated low sensitivity and high specificity, whereas clusters of findings including the lunge, manual muscle testing of the hip (lower extremities), and passive range of motion of the hip demonstrated the strongest diagnostic value. Selected tests and measures are moderately discriminatory in diagnosing PGP. A classification system for diagnosing PGP demonstrates strong agreement and may be useful for clinicians.