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

OBJECTIVE

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).

DESIGN

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.

RESULTS

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.