ODP063 Development and Validation of Model for Sparing Adrenal Venous Sampling in Diagnosing Unilateral Primary Aldosteronism

CONTEXT: Current guidelines recommend adrenal venous sampling (AVS) to identify unilateral primary aldosteronism (UPA) before offering adrenalectomy. However, AVS is costly and technically challenging, limiting its use to expert centres. OBJECTIVE: To establish a model to predict UPA and therefore bypass the need for AVS prior to surgery. Design and Setting: The model was developed in a Chinese cohort and validated in an Australian cohort. Previously published prediction models of UPA were also tested. Participants: PA patients with a definite subtyping diagnosis based on AVS and/or surgery. Main Outcome Measure: Diagnostic value of the model. RESULTS: In the development cohort (268 UPA and 88 bilateral PA), combinations of different levels of low serum potassium (≤3. 0 or 3.5mmol/L), high PAC (≥15-30ng/dL), low PRC (≤2.5-10μIU/mL) and presence of unilateral nodule on adrenal CT (>8-15mm in diameter) showedspecificity of 1. 00 and sensitivity of 0.16-0.52. The model of serum potassium≤3.5mmol/l, PAC≥20 ng/dL, PRC≤5μIU/mL plus a unilateral nodule≥10mmhad the highest sensitivity of 0.52(0.45-0.58) and specificity of 1. 00(0.96-1. 00). In the validation cohort (84 UPA and 117 bilateral PA), the sensitivity and specificity of the model were 0.13(0. 07-0.22) and 1. 00(0.97-1. 00), respectively. Ten previous models were tested, and only one had a specificity of 1. 00 in our cohorts, but with a very low sensitivity [0. 07(0. 04-0.10) and 0. 01(0. 00-0. 06) in our development and validation cohorts, respectively]. CONCLUSIONS: A combination of high PAC, low PRC, low serum potassium and unilateral adrenal nodule could accurately determine PA subtype in 13-52% of patients with UPA and obviate the need for AVS before surgery. Presentation: No date and time listed