Diagnostic Sensitivity and Specificity of Spectral Color Doppler Ultrasound Indices in Juvenile Idiopathic Arthritis

Objective: Subjectivity in diagnosing arthritis by clinical parameters has led to the use of power color Doppler Ultrasonography (USG) indices color fraction and resistive index (RI) to objectively assess synovitis. Cut off levels of these USG parameters have also been derived in adult patients with rheumatoid arthritis. This study was performed in children with juvenile idiopathic arthritis ( JIA) using power color Doppler to find out diagnostic cut off values of color fraction and RI in diagnosing arthritis. Methods: A cross sectional observational study was conducted .Forty children of JIA having active arthritis and thirty four age and sex matched healthy controls were evaluated by power color and spectral USG .Their mean color fraction and resistive index (RI) were derived and compared . Using ROC curve, cut off values of these indices was derived. Finally, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of these cut off values were calculated. Results: A total of 187 diseased joints and 200 healthy joints were evaluated by power color Doppler and spectral Doppler USG. Color fraction was significantly higher and RI signifi cantly lower among cases than controls when both pooled and individual joint data were compared. Cut off level of color fraction and RI of all joints pooled together was 1.00 and 0.711 respectively. Similarly cut off value of individual joint group of these two indices and sensitivity, specificity, PPV and NPV were derived. Conclusion: A highly significant differ ence was observed in color fraction and RI between cases and controls. Color Fraction and RI were found to be very sensitive and specific in diagnosing arthritis in JIA patients with very high PPV and NPV.