Validation of a prediction rule for renal artery stenosis.
OBJECTIVE
We previously developed a prediction rule to estimate the probability of renal artery stenosis. This rule should be validated before it can be used reliably to select hypertensive patients for renal angiography. We determined the validity of the prediction rule in recent patients and in other settings.


METHODS
We studied three aspects of validity (agreement between predicted and observed probability of stenosis, discriminative ability, and clinical usefulness) in 180 consecutive patients with drug-resistant hypertension and normal or mildly impaired renal function, who visited six hypertension clinics of academic and community hospitals in the Netherlands. Thirty-five patients (19%) had a significant stenosis.


RESULTS
The clinical characteristics in the rule (age, sex, vascular disease, recent onset of hypertension, smoking, body mass index, abdominal bruit, serum creatinine concentration, and hypercholesterolemia) had similar predictive value in the validation sample and development sample. The predicted probabilities of stenosis agreed well with the observed frequencies (Hosmer-Lemeshow goodness-of-fit test, P = 0.87). The prediction rule discriminated reasonably between patients with and without stenosis in the validation sample with an area under the receiver operating characteristic curve of 0.71. If only patients with predicted probabilities of stenosis of 5% or more were referred for renal angiography, the number of referrals was reduced by 20%, while 9% of patients with a stenosis were missed.


CONCLUSIONS
The prediction rule was valid in more recently treated patients in other settings. If used conservatively, the rule can reliably exclude a small proportion of patients from angiography.
Krijnen
Pieta
P
Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands. p.krijnen@ikw.nl
Steyerberg
Ewout W
EW
Postma
Cornelis T
CT
Flobbe
Karin
K
de Leeuw
Peter W
PW
Hunink
M G Myriam
MG
D017677:Age Distribution; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000150:complications; D003404:Creatinine / Q000097:blood; D005260:Female; D006764:Hospitals, Community; D006785:Hospitals, University; D006801:Humans; D006973:Hypertension / Q000150:complications; D008297:Male; D015233:Models, Statistical; D011237:Predictive Value of Tests; D012372:ROC Curve; D012078:Renal Artery Obstruction / Q000150:complications / Q000175:diagnosis*; D015203:Reproducibility of Results; D012907:Smoking / Q000009:adverse effects
D003404:Creatinine