Interobserver agreement on captopril renography for assessing renal vascular disease.
Captopril-stimulated renography is widely used to screen selected groups of hypertensive patients for renal vascular disease. Evaluation of the test is a complex task. Lack of interobserver agreement on the assessment and interpretation of renographic parameters may contribute to differences in sensitivity and specificity between studies.


METHODS
Three experienced nuclear medicine physicians evaluated 658 renograms of 503 hypertensive patients suspected of having renal vascular disease from a large Dutch multicenter study (the Dutch Renal Artery Stenosis Intervention Cooperative [DRASTIC] study). Interobserver agreement on several renographic parameters was assessed by the kappa statistic and the intraclass correlation coefficient (ICC).


RESULTS
The interobserver agreement on the time to excretion was high: The pooled ICC was 0.90. The pooled kappa was > or = 0.65 for the pattern of the time--activity curves, the visual aspect of the scintigraphic images (visible uptake and kidney size), and the judgment on the presence of renal artery stenosis. However, the interobserver agreement on cortical retention and pelvic retention by visual inspection of the images was rather low (pooled kappa = 0.46 and 0.52, respectively). Pelvic retention was found to complicate the interpretation of renography.


CONCLUSIONS
Interobserver agreement on most of the renographic parameters was satisfactory, but the assessment of cortical retention was more difficult, in particular, in the presence of pelvic retention. Captopril renography should be interpreted with caution if pelvic retention is suspected. Interobserver variability offers one of several explanations for the differences in diagnostic test performance that are found between studies.
Krijnen
Pieta
P
Center for Clinical Decision Sciences, Department of Public Health, Erasmus University Rotterdam, Rotterdam, The Netherlands. krijnen@mgz.fgg.eur.nl
Oei
Hong-Yoe
HY
Claessens
Roel A M J
RA
Roos
Jan C
JC
van Jaarsveld
Brigit C
BC
Habbema
J Dik F
JD
D000293:Adolescent; D000328:Adult; D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors; D002216:Captopril; D005260:Female; D006801:Humans; D006978:Hypertension, Renovascular / Q000000981:diagnostic imaging*; D007668:Kidney / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging; D017263:Technetium Tc 99m Mertiatide
D000806:Angiotensin-Converting Enzyme Inhibitors; D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide; D002216:Captopril