How accurate is DMSA scintigraphy for the diagnosis of acute pyelonephritis? A meta-analyis.

JC Craig, D Wheeler, L Irwig, RB Howman-Giles

Centre for Kidney Research, Royal Alexandra Hospital for Children, Westmead NSW, Australia

The objectives of this study were to evaluate the performance of DMSA scintigraphy for the diagnosis of acute pyelonephritis and to compare the test performance of the standard technique, planar DMSA, with the newly introduced technique, single photon emission computerized tomography (SPECT) DMSA. All published studies in which DMSA scintigraphy was compared with histopathology, the reference standard for acute pyelonephritis, and in animals were identified using a comprehensive search strategy of MEDLINE and EMBASE. Test performance of all DMSA methods and SPECT versus planar DMSA were analyzed using summary receiver operating characteristic curves (sROC). Seven studies were identified, including two of SPECT DMSA. Problems in study design and/or reporting were common, with numerical errors in four studies. Overall at a sensitivity of 86%, specificity was estimated to be 91%. Detection of acute pyelonephritis was at a lower threshold for SPECT than planar DMSA (sensitivity/specificity values of 97%/66% compared with 82%/97%) and the overall test performance of SPECT was not demonstrably better than planar DMSA. Applied to a group of children with a prevalence of renal damage of 40%, this means 98% of children with an abnormal planar DMSA scan will have renal damage, but only 65% of those with an abnormal SPECT scan. 11% and 3% of children with renal damage will be missed by planar and SPECT DMSA, respectively. In 100 of these children, compared with planar DMSA, SPECT will detect 6 extra true cases of renal damage at the expense of 19 extra false positives. In conclusion, published studies of DMSA test performance are few in number and have significant methodological problems that should be avoided in future studies. DMSA, particularly the planar technique, performs well for the diagnosis of acute pyelonephritis. Using test performance criteria, SPECT DMSA alone has not been shown to be preferable to the established planar method, and if used will result in a small number of true positives at the expense of a larger number of false positives.

Presented at the American Society of Nephrology Philadelphia October 1998

Correspondence
Dr Jonathan Craig
JonC@chw.edu.au