How to limit screening of patients for atheromatous renal artery stenosis in two-drug resistant hypertension?

BACKGROUND

The DRASTIC model based on nine variables (age, gender, recent onset of hypertension, smoking status, body mass index (BMI), abdominal bruit, atherosclerosis, dyslipidemia and creatininemia) has been proposed to predict renal artery stenosis (RAS) occurrence.

METHODS

In a prospective multicenter study, the clinical usefulness of the DRASTIC model was checked in 336 patients with two-drug resistant hypertension. RAS was excluded using at least color Doppler sonography. RAS was diagnosed using at least renal angiography. The statistical dependence (Z(Rho)) analysis was applied to investigate further the relationships between each variable and presence of RAS.

RESULTS

The prevalence of RAS (n=51) was 15%. The goodness-of-fit test that compared observed RAS to predicted RAS using the DRASTIC model was not significant. Accordingly, the multivariate logistic regression indicated that only three parameters (abdominal bruit, atherosclerotic vascular disease and BMI <25 kg/m2) were significantly linked to RAS. The Z(Rho) methodology revealed that calculated renal function <60 ml/min and age >58 yrs (median) were also significantly linked to RAS. No variable or combination of variables offered satisfactory positive predictive values for the RAS diagnosis. The combination of the five significantly linked variables had a negative predictive value of 98%, and allowed RAS detection with a sensitivity of 96%. In our population, RAS screening could have been avoided in 30% of our patients screened.

CONCLUSIONS

The DRASTIC model was unsuitable for clinical use in our sample population. In our population, renal arteries were considered stenosis free with a probability of 98% in refractory hypertensive overweight patients, aged < or = 58 yrs, with satisfactory renal function and without both abdominal bruit and atherosclerotic vascular disease.