The diagnostic value of conventional radiography and musculoskeletal ultrasonography in calcium pyrophosphate deposition disease: a systematic literature review and meta-analysis

Abstract

To examine and compare the accuracy of conventional radiography (CR) and musculoskeletal ultrasonography (US) in the diagnosis of calcium pyrophosphate (CPP) crystals deposition disease (CPPD). A systematic search of electronic databases (PubMed, Embase, and Cochrane), conference abstracts and reference lists was undertaken. Studies which evaluated the accuracy of CR and/or US in the diagnosis of CPPD, using synovial fluid analysis (SFA), histology or classification criteria as reference tests were included. Subgroup analyses by anatomic site and by reference test were performed. Twenty-six studies were included. Using SFA/histology as reference test, CR and US showed an excellent (CR AUC=0.889, 95%CI=0.811-0.967) and an outstanding (US AUC=0.954, 95%CI=0.907-1.0) diagnostic accuracy (p<0.01), respectively. Furthermore, US showed a higher sensitivity (0.85, 95%CI=0.79-0.90 vs 0.47, 95%CI=0.40-0.55) and only a little lower specificity (0.87, 95%CI=0.83-0.91 vs 0.95, 95%CI=0.92-0.97) than CR. A considerable heterogeneity between the studies was found, with adopted reference test being the main source of heterogeneity. In fact, subgroup analysis showed a significant change in the diagnostic accuracy of CR, but not of US, using Ryan and McCarty criteria or SFA/histology as reference test (CR: AUC=0.956, 95%CI=0.925-1.0 vs AUC=0.889, 95%CI=0.828-0.950, respectively, p<0.01) (US: AUC=0.922, 95%CI=0.842-1.0 vs AUC=0.957, 95%CI=0.865-1.0, respectively, p=0.08) CONCLUSIONS: Although US is more sensitive and a little less specific than CR for identifying CPP crystals, both these two techniques showed a great diagnostic accuracy and should be regarded as complementary to each other in the diagnostic work-up of patients with CPPD.