SUN-230 Consideration of pretest probabilities when using RASI score for selection of surgical candidates, a metanalysis of adrenal vein sampling studies

Abstract Disclosure: G. Ling: None. R. Akande: None. S.G. Albert: None. Primary aldosteronism (PA) may be grouped into unilateral PA (UPA), amenable to surgery, and bilateral PA (BPA,) benefiting from medical therapy. The distinction between the groups may be made with adrenal vein sampling (AVS). Whereas catheterization of the left sided (LS) confluence of the renal/adrenal vein is usually successful, it is difficult to catheterize the right side (RS) adrenal vein. When bilateral catheterization is incomplete, surgery may still be considered. Studies have evaluated the predictive value of RASI [Relative Aldosterone Secretion Index= Ratio of left AV Aldosterone (A)/Cortisol (C) vs inferior vena cava (IVC) A/C] in localization of UPA. We performed a meta-analysis for AVS in hyperaldosteronism. Of 377 trials evaluated, 8 trials (n=1487 patients) included RASI vs clinical outcomes as defined in the primary source. The prevalence of UPA ranged from 37% to 85%. There was a negative correlation of RASI vs prevalence of UPA (r= -0.744 p=0.021) using an inverse-square random-effects meta-regression. Studies with lower prevalence of UPA required higher RASI for localization of the ipsilateral UPA. The largest study, AVIS, would have required a LS-RASI >7.8 to limit false positive referrals to surgery to <10%. The predictive value of LS-RASI for localization of LS-UPA correlated with baseline serum aldosterone to renin (ARR) ratios (r=-0.675, p=0.040). Conversely, localization of a RS-UPA with a 95% probability was associated with a suppressed LS-RASI of <0.43, and was independent of baseline ARR. A theoretical Bayesian analysis of retrospective data from the published AVIS trials (of tumor size and of RASI) was used to predict the positive predictive value (PPV) of a LS-RASI to localize a LS-UPA. The PPV would be the major determinant for correctly assigning patients to surgery. The PPV was most dependent upon the prevalence of UPA in the population rather than the tumor size on imaging. Further analyses need to be performed to validate these assumptions. Until these analyses to predict prevalence of UPA are performed, LS-RASI may not be considered a reliable indicator for LS-UPA. A suppressed LS-RASI <0.43, and presence of a right-sided nodule on imaging may be highly suggestive of unilateral RS-UPA. Presentation: Sunday, July 13, 2025